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1
Wang, Qing Hui, Hua Wu et Tao Chen. « The Mechanical Properties of 20MnSi Steel and Welding Research ». Applied Mechanics and Materials 281 (janvier 2013) : 395–99. http://dx.doi.org/10.4028/www.scientific.net/amm.281.395.
Texte intégralRésumé :
The microstructure, mechanical properties, precipitation of micro alloying elements and welding performance of self-designed 20MnSi steel were investigated, by means of metallographic microscope , transmission electron microscope, electroslag pressure welding and mechanics performance tests, etc.The results show that,with the actions of microalloy V and controlled rolling and controlled cooling technique, tensile strength (Rm) and yield strength (Rel) of the test bar could respectively reach 730 MPa and 560 MPa, uniform elongation (Agt %) of 13.5%, which has met the seismic performance index. And we found that a lot of dispersion particle V (CN) precipitated in the ferritic matrix and grain boundary place, which have a good precipitation strengthening and refining grain effect. In addition, based on the welding parameters reasonable controlling, it can make the mechanical properties of welding joints changes not beyond the design range, and satisfy the use requirement.
2
Chung, Junho, Taeh Yung Kim et Ju Sang Lee. « Study on the Effect of V Microalloying on Earthquake Resisting High-Strength Reinforcing Bar Steels ». Materials Science Forum 1016 (janvier 2021) : 345–53. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.345.
Texte intégralRésumé :
Recently, the frequency of earthquakes has been increasing worldwide. As a result, steel reinforced with seismic performance that can satisfy the social needs to strengthen the existing seismic performance of existing infrastructure facilities and new buildings has become important. In general, to secure the yield strength of reinforcing bars and to reduce the production cost, reinforcing bars are produced by rolling the surface through a facility such as a Tempcore. In Korea, most of them have adopted the Tempcore process to ensure the mechanical requirements of the product. However, the use of a small amount of alloying elements and the application of Tempcore have limitations in producing reinforcing bars that require seismic performance. In recent years, remarkable progress has been made in the production and application of high strength rebars. Microalloying and fine-grain strengthening are the most effective methods in developing high strength rebars. That is, the precipitation of V (C, N) is promoted by the addition of V to improve the strength by precipitation strengthening of V-carbonitride. However, in V-microalloyed reinforcing bars, it was confirmed that the required strength did not increase proportional to the amount of V added. In this study, the effects of vanadium and other alloying elements on the mechanical properties and yield ratio of steel bars were investigated by tensile test results and microstructural evaluation.
3
Huo, Bao Rong, et Xiang Dong Zhang. « Experiment Study of BFRP Bars’ Mechanical Properties ». Applied Mechanics and Materials 174-177 (mai 2012) : 830–33. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.830.
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The testing rule of mechanical properties of material can be established and the mechanical performance can be found by studying the basic mechanical properties of BFRP bars. Using the opressive sleeve anchor developed by the researchers,tensile tests of BFRP bars are carried out according to the national standards of “GFRP bar tensile test methods”.The BFRP bar’s force-deformation curve is linear before the force-deformation relationship is destroyed,therefore,referring to steel wire or steel cable,the BFRP bar’s reliable strength is suggested to be approximately 80% of its ultimate tensile strength. The BFRP bar’s tensile elastic modulus is related to the content of basalt fiber.The tensile elastic modulus increases with the increase of the basalt fiber’s content and the content increases when the BFRP bar’s diameter becomes longer, so the tensile elastic modulus increases with the increase of its diameter. Compared with steel, the BFRP bar is obviously superior in the aspects of tensile strength, corrosion resistance ,etc,therefore to use the BFRP bar in reinforced concrete structures insead of steel is feasible.
4
Mo, Fei, Pu Zhang, Dan Ying Gao, Yu Yang Pang et Ke Zhao. « Experimental Method Study on Tensile Properties of GFRP Bar ». Applied Mechanics and Materials 438-439 (octobre 2013) : 365–68. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.365.
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The GFRP bar has good mechanical properties and durability, but it is hard to test the tensile strength of large diameter FRP bar. Its test method given by ACI is too conservative, especially for large diameter FRP bar, and the length of test specimen will be too long and beyond the range of most testing machine. This article tested the tensile strength of GFRP bar using new methods, meanwhile, analyzed its stress distribution along the length of the specimens. The test results show that the use of bond anchor with steel plug or internal thread to measure the tensile strength of GFRP bar is feasible, and it can reduce the free length and the anchor length of the specimens, thus simplifying the test method of the tensile strength of FRP bars.
5
Xu, Xin Sheng, Ning Zhang et Tao Ji. « Mechanical Property of FRP Bar and Design Method of Hybrid FRP Bar ». Materials Science Forum 620-622 (avril 2009) : 339–42. http://dx.doi.org/10.4028/www.scientific.net/msf.620-622.339.
Texte intégralRésumé :
The paper described the detailed design and production method of the FRP bar and the anchorage device, and it also introduced the test method of mechanical properties on the tensile strength, elastic modulus and the rate of elongation of the FRP bar. Moreover, it conducted statistical analysis into test results and put forward the mechanical property index for structural design of the FRP bar concrete. Test results indicated that stress-strain relation of the FRP bar presented linear variation. FRP bar is superior to steel bar concerning high tensile strength-quality ratio and high durability, the elastic modulus and the rate of elongation of the FRP bar are also less than those of the steel bar, it is practicable to use FRP bar as a new type of tensile material in concrete structures. And then, it put forward design ideas of the hybrid FRP bar by a series of analysis on the hybrid effect and the ductility of the hybrid FRP bar.
6
Benmokrane, Brahim, Burong Zhang, Kader Laoubi, Brahim Tighiouart et Isabelle Lord. « Mechanical and bond properties of new generation of carbon fibre reinforced polymer reinforcing bars for concrete structures ». Canadian Journal of Civil Engineering 29, no 2 (1 avril 2002) : 338–43. http://dx.doi.org/10.1139/l02-013.
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This paper presents laboratory test results on the mechanical properties and bond strength of new generation of carbon fibre reinforced polymer (CFRP) reinforcing bars used as nonprestressed reinforcement for concrete structures. Two types of CFRP reinforcing bars, namely, 9-mm-diameter CFRP ribbed bars and 9.5-mm-diameter CFRP sand-coated bars, were investigated. Tensile tests and pullout bond tests were conducted to evaluate the tensile properties and bond strength of the CFRP bars in comparison with that of the steel bar. Experimental results showed that the tensile stress-strain curves of the CFRP bars were linear up to failure. The ultimate tensile strength of the two types of CFRP bars was at least 1500 MPa, three times that of steel bars. The modulus of elasticity of two types of the CFRP bars was 128145 GPa, about 6575% that of steel. Furthermore, both types of the CFRP bars exhibited almost the same bond strength to concrete similar to steel bars. The minimum bond development length for the two types of CFRP bars seemed to be equal to about 20db for the sand-coated bars and 30db for the ribbed bars.Key words: fibre reinforced polymer (FRP), carbon FRP (CFRP), bar, mechanical properties, tensile strength, embedded length, pullout, bond strength, concrete structures.
7
Sun, Zeyang, Yu Tang, Yunbiao Luo, Gang Wu et Xiaoyuan He. « Mechanical Properties of Steel-FRP Composite Bars under Tensile and Compressive Loading ». International Journal of Polymer Science 2017 (2017) : 1–11. http://dx.doi.org/10.1155/2017/5691278.
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The factory-produced steel-fiber reinforced polymer composite bar (SFCB) is a new kind of reinforcement for concrete structures. The manufacturing technology of SFCB is presented based on a large number of handmade specimens. The calculated stress-strain curves of ordinary steel bar and SFCB under repeated tensile loading agree well with the corresponding experimental results. The energy-dissipation capacity and residual strain of both steel bar and SFCB were analyzed. Based on the good simulation results of ordinary steel bar and FRP bar under compressive loading, the compressive behavior of SFCB under monotonic loading was studied using the principle of equivalent flexural rigidity. There are three failure modes of SFCB under compressive loading: elastic buckling, postyield buckling, and no buckling (ultimate compressive strength is reached). The increase in the postyield stiffness of SFCB rsf can delay the postyield buckling of SFCB with a large length-to-diameter ratio, and an empirical equation for the relationship between the postbuckling stress and rsf is suggested, which can be used for the design of concrete structures reinforced by SFCB to consider the effect of reinforcement buckling.
8
Liu, Yue, Hong-Tao Zhang, Hong-Hao Zhao, Lin Lu, Ming-Yang Han, Jiao-Cai Wang et Shuai Guan. « Experimental Study on Mechanical Properties of Novel FRP Bars with Hoop Winding Layer ». Advances in Materials Science and Engineering 2021 (3 août 2021) : 1–18. http://dx.doi.org/10.1155/2021/9554687.
Texte intégralRésumé :
Due to the fact that steel reinforcement is vulnerable to corrosion, FRP bars with light weight, high strength, and excellent durability have become a good substitute for ordinary steel bars. FRP bars have high tensile strength, but their compressive strength is relatively low and often neglected, so the application of FRP bars in compression members has been restricted. This paper proposes a new pultrusion-winding-pultrusion method to improve the compressive ability of FRP bars. A hoop FRP layer is winded on the outer surface of the pultruded FRP core, and a longitudinal pultruded layer and ribs are also added on the outermost surface. In this paper, mechanical properties of this novel FRP bar with hoop winding layer are investigated. First, monotonic tensile and compressive tests on traditional and novel GFRP bars were conducted. Then, cyclic tension-compression loading tests were also carried out on the two types of GFRP bars. Test results showed that the compressive ultimate bearing capacities of GFRP bars with winding layers were 10∼20 kN greater than those of the traditional GFRP bars, and the compressive ductility of the novel GFRP bars was also improved. Furthermore, the tensile stress-strain behaviors of both GFRP bars were linear-elastic and the added winding layer did not greatly influence the tensile properties of the GFRP bars. Moreover, for the cyclic loading test, the compressive ultimate load of GFRP bars was 80%∼90% of that under monotonic compressive test, and the tensile ultimate load was 45%∼65% of that under monotonic tensile test. Compared with the GFRP bar without winding layer, the overall stiffness of the novel GFRP bar was greater than that of the traditional one and the ultimate load of the novel GFRP bar was also greater. In addition, seeing that the residual displacement of the novel GFRP bar was greater than that of the traditional GFRP bar, winding hoop fibers on the outer surface of the core is a useful way to improve the energy dissipation capacity of the GFRP bar.
9
Durães, M., et Nuno Peixinho. « Dynamic Material Properties of Stainless Steel and Multiphase High Strength Steels ». Materials Science Forum 587-588 (juin 2008) : 941–45. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.941.
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This work presents results of tensile testing of H400 stainless steel, DP600 and TRIP600 at different strain rates. Mechanical properties were determined from tensile test using flat sheet specimens and recurring to different test techniques: servo-hydraulic machine and a tensile-loading Hopkinson bar. The test results were used to compare different mechanical properties of the tested steels and to validate constitutive equations intended to provide a mathematical description of strain rate dependence, namely the Cowper-Symonds equation. Following previous research work in dynamic material proprieties of multiphase and stainless steel grades, the energy absorption in quasi-static crushing of thin walled section made of the tested materials was subsequently investigated. Crush tests were performed in top-hat and hexagonal section tubes manufactured using laser welding. The experimental results were compared in order to assess the efficiency of the different steel grades for energy absorption.
10
Xiao, Gui Zhi, Jun Xue Zhao et Li Li Zhuang. « Study on Microstructure and Properties of High Strength Construction Steel Bars ». Advanced Materials Research 368-373 (octobre 2011) : 3787–90. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.3787.
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In this paper, the microstructure and properties construction steel bars under various quenching and tempering temperature are investigated. Tensile tests show that the maximum tensile strength is1489MPa, elongation 11%, quenching temperature and tempering temperature have effects on the strength and plasticity of the samples, but the latter effect is more pronounced than the former. Steel bars have superior delayed fracture resistance between 390 ~420°C. The microstructure of steel bar is mainly composed of fine tempered sorbite (troostite) with carbide distributed along the lath martensite boundaries. Thus, we draw the conclusion thermal refining is an effective way to improve mechanical properties and delayed fracture resistance of high strength construction steel bars.
11
Yunan Hasbi, Muhammad, Muhammad Budiman et Bintang Adjiantoro. « Developing of Mechanical Properties for Reinforcing Bar Steel through Heat Treating with Various Cooling Media ». Solid State Phenomena 266 (octobre 2017) : 267–71. http://dx.doi.org/10.4028/www.scientific.net/ssp.266.267.
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In this study, mechanical properties development of reinforcing bar steel (rebar) has examined through heat treatment process. This rebar was made from low carbon lateritic steel with the small amount of alloying elements Cr,Mn and Ni. There were 4 rebar steel samples that consisted of rebar steel was applied hot rolled at 1200 °C at the beginning process in factory (sample A) and three others were conducted by quenching (sample B, C and D). The various of cooling media such as water (sample B), oil (sample C) and air (sample D) have applied to obtain different microstructure behavior and also mechanical properties. Initial heating was conducted to B,C and D rebar specimens at the austenitizing temperature (950 °C) for 1 h and followed by quenching. The experimental results showed that water quench exhibited of higher hardness level (50,26 HRC) for rebar steel but decreasing in toughness (34 Joule) and elongation (4%) than as cast because of martensite phase formed. Sample C showed that martensite and the small amount of retained austenite with hardness and tensile strength below the sample B, but elongation and energy absorbed were above. The lowest of hardness and tensile strength were obtained from sample D. It was appropriate with microstructuree formed as follows ferrite-pearlite phase and widmanstatten-bainite cluster. Nevertheless, sample D is suitable treatment for tensile strength and elongation requirements rebar standard, there are 558 Mpa and 26% respectively (min. 440 MPa and 20%).
12
Kim, Seon Jin, Yu Sik Kong, Yeong Sik Kim et Sang Woo Kwon. « On Mechanical Properties of Dissimilar Friction Welded Steel Bars ». Key Engineering Materials 297-300 (novembre 2005) : 2831–36. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.2831.
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An experimental study of dissimilar friction welding was conducted using 15mm diameter solid bar in chrome molybdenum steel (SCM440) to carbon steel (S45C) not only to optimize the friction welding conditions, but also to investigate the fatigue performance. The main friction welding parameters were selected to endure good quality welds on the basis of visual examination, tensile tests, Vickers hardness surveys of the bond of area and HAZ, and microstructure investigations. In this study, the specimens were tested as welded. For fatigue strength, the notched specimens for the optimal conditions were rotary bending fatigue tested. The results were compared with S-N curves for the base metals.
13
Mao, Ji Ze, Hong Wei Zhang, Jian Fu Lv, Dao Guang Jia et Shi Kai Ao. « Mechanical Properties and Corrosion Mechanism of GFRP Rebar in Alkaline Solution ». Key Engineering Materials 665 (septembre 2015) : 217–20. http://dx.doi.org/10.4028/www.scientific.net/kem.665.217.
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Steel corrosion is one of the main problems of concrete structure durability. Compared with the steel, GFRP rebar has the advantages of high strength, low density and good corrosion resistance. Therefore, GFRP becomes a good choice to replace steel bar in concrete structure. Since GFRP material is susceptible to the alkaline conditions, it is necessary to clarify the mechanical properties and corrosion mechanism of GFRP rebar in such an alkaline environment of interior concrete. In this study, the artificial accelerated corrosion tests of two kinds of GFRP rebar (epoxy and unsaturated polyester resin matrix) were conducted at 60 °C in alkaline solution up to 90 days. Then the tensile strength tests of GFRP rebar were carried out. The solution PH values, the tensile strength and mass loss of GFRP rebar were measured. The testing results show that the mass of GFRP rebar had rarely changed, but the tensile strength reduced about 30% after 90-day immersion test in alkaline solution. During the test, the PH value of the alkaline solution decreased from 13.62 to around 12.85, which indicated that the hydroxyl ions of the alkaline solution had been consumed. The ester bonds in resin matrix may hydrolyze in alkaline solution and the bonding interface between fiber and resin can be damaged progressively. It can cause the performance degradation of GFRP rebar. In addition, the relationship between the loss of tensile strength and the reduction of PH can be determined. That means the durability of GFRP rebar in concrete can be enhanced by controlling or limiting the alkalinity when producing concrete. Finally, the GFRP rebar of epoxy resin matrix shows higher retention values of tensile strength and better alkali resistance than those of UPR matrix rebar after 90d immersion in the alkaline solution. The obtained results in this paper can provide application reference of GFRP materials in civil engineering.
14
Wang, Ying, et Ping Li. « Corrosion Behavior of Reinforcing Steel Bar HPB235 in NaCl Solution ». Advanced Materials Research 287-290 (juillet 2011) : 738–41. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.738.
Texte intégralRésumé :
The corrosion behavior of reinforcing steel bar HPB235 in concrete structure in 0.5% NaCl solution was investigated and its mechanical properties were tested before and after corrosion. The results showed that, with corrosion time increasing from 240h to 720h, the corrosion rate increases and the corrosion becomes heavier and heavier, but the corrosion scale is not changed obviously in compositions. After 720h, the yield strength is decreased by less than 5%, but the tensile strength and the elongation are decreased by more than 10%.
15
Zhao, Lei, Shengjiang Sun et Wei Qi. « Study on The Mechanical Properties of Steel - Basalt Fiber Composite Reinforcement (SBFCBs) ». E3S Web of Conferences 165 (2020) : 05028. http://dx.doi.org/10.1051/e3sconf/202016505028.
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Steel bar and Basalt Fiber are combined to obtain a new structural material with high strength, high elastic modulus, high toughness, corrosion resistance, low cost and other excellent comprehensive performance: Steel Basalt Fiber Composite Bars (SBFCBs). In this paper, three different types of composite bars were tested by monotonic tensile tests, and the failure patterns of steel bars were introduced in the process of stretching, and the yield strength, ultimate strength, elastic modulus and stress-strain curves of steel bars were obtained. Test results showed that the stress-strain curve of SBFCBs was obviously double-folded, and SBFCBs exhibited stable post-yielding stiffness after the reinforcement yielded. The stress-strain curve model of SBFCBs under uniaxial tension was derived according to the material’s compounding rule. By sorting the experimental data and comparing it with theoretical values, we could prove the accuracy of the model.
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PROCHENKA, Paweł, et Jacek JANISZEWSKI. « Assessment and Comparison of the Mechanical Properties of Laser Welded Joints in Docol 1200M and Strenx S700MC Steel Alloy Grades Under Impact Loads ». Problems of Mechatronics Armament Aviation Safety Engineering 11, no 1 (31 mars 2020) : 17–30. http://dx.doi.org/10.5604/01.3001.0014.0282.
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The article evaluates the strength and ductility of laser butt joints made of 2 mm Docol 1200 M martensitic steel sheets based on the hardness, quasi-static and dynamic tensile tests. Technological research of laser welding process was carried out on welding cell using IPG fiber – based welding source with 6 kW maximum power. The tests were carried out for parallel and perpendicular orientation of specimens by rolling direction. In addition, the obtained results were compared with the analogous results obtained during the Strenx S700 MC steel tests. Dynamic tests were performed using the tensile split Hopkinson pressure bar technique with strain rates of 103 s-1. The obtained results showed that the strength of Docol 1200 M under dynamic tensile test conditions are similar to the material strength under static tensile test conditions. However, due to the breaking of the specimens in the heat affected zone, the strength of the welded joint is much lower than in base material, which was not observed during the Strenx S700 MC steel tests.
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Li, Qingfu, Yunqi Cui et Jinwei Wang. « Basic Mechanical Properties of Duplex Stainless Steel Bars and Experimental Study of Bonding between Duplex Stainless Steel Bars and Concrete ». Materials 14, no 11 (1 juin 2021) : 2995. http://dx.doi.org/10.3390/ma14112995.
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In recent years, as a result of the large-scale use of stainless steel bars in production and life, people’s demand for stainless steel bars has increased. However, existing research information on stainless steel bars is scant, especially the lack of research on the mechanical properties of duplex stainless steel bars and the bonding properties of duplex stainless steel bars to concrete. Therefore, this paper selects 177 duplex stainless steel bars with different diameters for room temperature tensile test, and then uses mathematical methods to provide suggestions for the values of their mechanical properties. The test results show that the duplex stainless steel bar has a relatively high tensile strength of 739 MPa, no significant yield phase, and a relatively low modulus of elasticity of 1.43 × 105 MPa. In addition, 33 specimens were designed to study the bonding properties of duplex stainless steel bars to concrete. In this paper, the effects of concrete strength, duplex stainless steel reinforcement diameter, the ratio of concrete cover to reinforcing steel diameter, and relative anchorage length on the bond stress were investigated, and a regression model was established based on the experimental results. The results show that, with the concrete strength concrete strength from C25 to C40, the compressive strength of concrete increased by 56.1%, the bond stress increased by 27%; the relative anchorage length has been increased from 3 to 6, the relative anchorage length has doubled, and the bond stress has increased by 13%; and, the ratio of concrete cover to reinforcing steel diameter increased to a certain range on the bond stress has no significant effect and duplex stainless steel reinforcement diameter has little effect on the bond stress. The ratio of concrete cover to reinforcing steel diameter from 3.3 to 4.5 and the bond stress increased by 24.7%. A ratio of concrete cover to reinforcing steel diameter greater than 4.5 has no significant effect on the bond stress, with the average bond stress value of 20.1 MPa. The duplex stainless steel bar diameter has little effect on the bond stress for the diameters of 12 mm, 16 mm, 25 mm duplex stainless steel bar, and their average bond stress is 19.9 MPa.
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Qin, Jin Gui, Fang Yun Lu, Yu Liang Lin et Xue Jun Wen. « Effect of Loading Rate on Tensile Properties of Automotive Steel Sheet ». Advanced Materials Research 690-693 (mai 2013) : 211–17. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.211.
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Results of uni-axial tensile loading of three automotive steels at different strain rates (0.0011–3200s-1) are reported here. Quasi-static tensile tests were performed under the strain rate of 1.1×10-3 s-1 using an electromechanical universal testing machine, whereas dynamic tests were carried out under the strain rate in the range of 1100 to 3200 s-1 using a Split Hopkinson Tensile Bar apparatus. Based on the experimental results, the material parameters of widely used Johnson–Cook model which described the strain rate and temperature-dependent of mechanical behaviour were determined. The experiments show that strain-rate hardening is superior to thermal softening: yield stresses, tensile strength, deformation, and energy dissipation increase with the strain rate from quasi-static tests to dynamic tests. The Johnson–Cook model can describe the behaviour of these steels and provides the opportunity to study the material and structural response.
19
Du, Wen Wen, Qian Wang, Lin Wang et Ding Wang. « Effect of Isothermal Heat Treatment on Dynamic Properties of a High Strength Steel ». Applied Mechanics and Materials 782 (août 2015) : 124–29. http://dx.doi.org/10.4028/www.scientific.net/amm.782.124.
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The high strength steel which was subjected with isothermal heat treatment at three different temperatures, namely 330°C, 350°Cand 380°C after different quenching temperature namely 880°C and 900°C,was investigated in this paper. The quasi-static and dynamic mechanical properties of new high strength steel was tested by universal material testing machine and Split Hopkinson Pressure Bar (SHPB). Experimental results have showed that the yield strength and tensile strength of the steel reach 1100MPa and 1400MPa respectively. Hardness, yield strength and toughness are found to decrease with the consequently increasing of isothermal temperature under the same quenching temperature. The compression properties of the steel under quenching temperature of 880°C are higher than that of 900°C with the same isothermal temperature. It can be found that the steel which is subjected with isothermal heat treatment show strain rate sensitivity under high velocity impact. When isothermal temperature is set 380°C, the steel exhibits the most obvious strain rate hardening effect.
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Bahleda, Bujňáková, Koteš, Hasajová et Nový. « Mechanical Properties of Cast-in Anchor Bolts Manufactured of Reinforcing Tempcore Steel ». Materials 12, no 13 (27 juin 2019) : 2075. http://dx.doi.org/10.3390/ma12132075.
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The tempcore process is implemented in rolling mills to produce high strength reinforcing steel. Besides being used as reinforcement, rebars are also used as the base material for the manufacturing of anchor bolts. The mechanical properties of reinforcement bars used in Europe are assessed in accordance with Eurocode without the recommendations for cast-in anchor bolts. The material properties of Tempcore rebars are not homogenous over the bar cross section. The European Assessment Document (EAD) for the cast-in anchor bolts does not exactly specify the mechanical properties of the thread part. The aim of these experiments is to show the different mechanical properties of rebars and their thread parts. The experiments were performed on rebars modified by peeling to characterize the reduction of diameter in a thread part. As a possible way to predict mechanical properties in a non-destructive way, the hardness tests were performed. Next, the application of the correlation relationship between hardness and tensile strength has been determined. The paper formulates preliminary recommendations for assessment of the cast-in anchor bolts in practice.
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Laber, Konrad Błażej, et Henryk Dyja. « The Effect of the Normalizing Rolling of S355J2G3 Steel Round Bars on the Selected Mechanical Properties of Finished Product ». Solid State Phenomena 165 (juin 2010) : 294–99. http://dx.doi.org/10.4028/www.scientific.net/ssp.165.294.
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The paper presents investigation results related to the effect of application of round plain bar normalizing rolling on the selected mechanical properties of finished product. The research was carried out for the process of rolling 38 mm-diameter plain round bars made of constructional steel S355J2G3, based on actual specifications used in industrial conditions in a continuous bar rolling mill. In the course of investigation the yield stress, YS, and the tensile strength, TS, were determined. With the aim of evaluating the effect of controlled (normalizing) rolling on the mechanical properties of the considered steel grade, Zwick Z/100 testing machine was employed and analytical relationships were used. On the basis of performed research work it was established that enhancement of mechanical properties of the considered steel can be obtained as a result of application of the normalizing rolling process.
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Chen, Peng Zhen, Francesco Finelli, Elisa Franzoni, Cristina Gentilini et Gabriele Sansone. « Preliminary Results on the Tensile Capacity of Steel Anchors in Brick Units of Different Materials ». Key Engineering Materials 817 (août 2019) : 371–76. http://dx.doi.org/10.4028/www.scientific.net/kem.817.371.
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High strength steel bars are widely used for the strengthening of masonry buildings, in particular to improve the connection between different structural elements, such as orthogonal walls and multi-leaf walls. A particular type of steel connector is the twisted bar, which due to its particular shape works as a self-threading screw, anchoring to the support material without any binder. The effectiveness of such technique mainly relies on the bond between the bar and the substrate, where adhesion, mechanical interlocking and friction play an important role. In this paper, a preliminary experimental study on pull-out behavior of twisted steel connectors inserted in brick units of different materials that can be commonly found in existing masonry buildings in Italy and in Europe is presented. Additionally, mechanical characterization of the materials is conducted to understand the influence of the compression strength and elastic modulus on the adhesion between the connector and the substrate. Preliminary results show that the pull-out response strongly depends on the mechanical properties of the substrate material.
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Chen, Qing Jun, An He, Guang Bin Pan, Jian Cai, Jun Li et Chun Yang. « Experimental Study on Bending Behavior of Cold-Rolled Deformed Steel Bars Reinforced Concrete Slabs ». Advanced Materials Research 639-640 (janvier 2013) : 341–45. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.341.
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Cold-rolled deformed bar with wing is a new type of cold-rolled deformed bar, it has high tensile strength and better ductility than the general cold-rolled deformed bars, and has good bonding properties with concrete. Five types of totally 15 full-scale specimens were tested to investigate the mechanical behavior, failure mode and the suitable value of minimum reinforcement ratio of concrete slab with cold-rolled deformed bar with wing. Experimental parameters include the reinforcement ratio, concrete strength, and reinforcement diameter. The deflection of mid-span, the strain of cold-rolled deformed bar and the crack width measured under each load level were studied. The test shows that the specimens with the reinforcement ratio of 0.15% present ductile failure, while those with the reinforcement ratio of 0.12% present brittle failure. Based on the results of the experiment, this paper suggests that the value of minimum reinforcement ratio of concrete slabs with cold-rolled deformed bar with wing could be 0.15%.
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Lu, Shi Kang, Yu Lai Chen et Wei Yu. « Prediction Model for Microstructure and Properties of Medium Carbon Non-Quenched and Tempered Steel Bar ». Materials Science Forum 993 (mai 2020) : 526–33. http://dx.doi.org/10.4028/www.scientific.net/msf.993.526.
Texte intégralRésumé :
In this study, the 38MnSiVS medium carbon non-quenched and tempered steel bar was investigated by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and quantitative metallography. The microstructures were mainly composed of ferrite and pearlite. The phase transition-microstructure prediction models were established to calculate ferrite volume fraction fα, ferrite grain size dα and pearlite interlamellar spacing So. The volume fraction of the second phase V (C, N) was calculated by thermodynamics. The morphology of the second phase V (C, N) was observed by TEM, and the distribution of particle size of the second phase was determined. And the mechanical properties were measured. Considering the microstructural parameters (fα,dα and So), the modified coefficient of solid solution elements, and the effect of precipitates, combining with some reference models, prediction model of mechanical properties including yield strength, tensile strength and impact toughness were finally established.
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MARCISZ, Jarosław, Bogdan GARBARZ et Jacek JANISZEWSKI. « Changes in Mechanical Properties of Ultrahigh Strength Nanostructured Steel Resulting from Repeated High Strain Rate Deformation ». Problems of Mechatronics Armament Aviation Safety Engineering 10, no 1 (31 mars 2019) : 99–120. http://dx.doi.org/10.5604/01.3001.0013.0800.
Texte intégralRésumé :
The paper contains results of investigation of nanostructured bainitic steel subjected to repeated high-strain-rate deformations using split Hopkinson pressure bar method and uniaxial compression of cylindrical specimens in Gleeble simulator. Steel of chemical composition Fe-0.58%C-1.80%Si-1.95%Mn-1.3Cr-0.7Mo (weight %), after isothermal heat treatment at 210°C, is characterized by following mechanical properties determined at static tensile test: yield strength YS0.2 = 1.3 GPa; ultimate tensile strength UTS = 2.05 GPa; total elongation E = 12%, hardness 610 HV and Charpy-V impact toughness 24 J at +20℃ and 14 J at -40℃. Stress-strain curves obtained for pre-stressed material before the next dynamic compression and after repeated compressions were analysed. Microstructure of the deformed specimens in areas of the dynamic impact was investigated. The effects of the dynamic repeated impact on changes in characteristics of the investigated material, in that on strain hardening mechanism, were established. Critical strains of 5.3% at strain rate 910 s-1 and about 10% at strain rate 50 s-1 for the nanostructured bainite were determined. Exceeding the critical strain under uniaxial repeated high-strain-rate compression, resulted in decreasing of ability of the steel for further plastic deformation and strain hardening.
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Brnic, Josip, Marino Brcic, Sanjin Krscanski, Jitai Niu, Sijie Chen et Zeng Gao. « Deformation Behavior of C15E + C Steel under Different Uniaxial Stress Tests ». Metals 10, no 11 (29 octobre 2020) : 1445. http://dx.doi.org/10.3390/met10111445.
Texte intégralRésumé :
In this paper, the mechanical properties of the material that define its mechanical behavior are experimentally investigated. All performed experimental tests and analyzes are related to C15E + C steel. The tested material was delivered as cold drawn round bar. It is usually used in mechanical engineering for design of low stressed components. Experimentally obtained results relate to the maximum tensile strength, yield strength, creep behavior, and uniaxial fully reversed high cyclic fatigue. Results representing mechanical properties are shown in the form of engineering stress–strain diagrams, while creep behavior of the material at different temperatures and different stress levels is displayed in the form of creep curves. Tests representing uniaxial cyclic fully reversed mechanical fatigue at constant stresses and room temperature in air are shown in the form of fatigue-life (S−N) diagram. Some of the experimental results obtained are as follows: ultimate tensile strength (σm(20 °C/500 °C)=(598/230) MPa), yield strength (σ0.2(20 °C/500 °C)=(580/ 214 ) MPa ), modulus of elasticity (E(20 °C/500 °C)=(213/106) GPa), and fatigue limit (σf(20 °C, R=−1)=250.83 MPa). The fatigue tests were performed at frequency of 40 Hz and at room temperature (20 °C) in air, with stress ratio of R=−1.
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Canbaz, Mehmet, et Uğur Albayrak. « Fracture patterns and mechanical properties of GFRP bars as internal reinforcement in concrete structures ». Challenge Journal of Concrete Research Letters 11, no 3 (8 septembre 2020) : 69. http://dx.doi.org/10.20528/cjcrl.2020.03.003.
Texte intégralRésumé :
Glass Fiber Reinforced Plastic (GFRP) composites as rolled bars can be used as steel rebar to prevent oxidation or rust which is one of the main reasons concrete structures deteriorate when exposed to chlorides and other harmful chemicals. GFRP is successful alternative for reinforcement with high tensile strength- low strain, corrosion resistance and congenital electromagnetic neutrality in terms of longer service life. The main goal of the study is to investigate the mechanical and bonding properties of GFRP bars and equivalent steel reinforcing bars then compare them. GFRP and steel rebar are embedded in concrete block with three different levels. Mechanical properties of GFRP and steel bars in terms of strength and strains are determined. On the other hand; modulus of elasticity of GFRP and steel bars, modulus of toughness and modulus of resilience were calculated using stress-strain curves, as a result of the experiments. Pull-out tests are conducted on each GFRP and rebar samples which are embedded in concrete for each embedment level and ultimate adherence strengths are determined in terms of bar diameter–development length ratio. Yield strength, strain and modulus of elasticities of GFRP samples are compared to steel rebar. According to the test results reported in this study, GFRP bars are used safely instead of steel bars in terms of mechanical properties.
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Hidayah, Febrianti Nurul, Ikha Farikha et Donald Edwin Maspaitella. « Mechanical Properties of Aramid Composite as an Alternative in Use of Steel on the Manufacture of CN-235 Aircraft Wings ». Materials Science Forum 1025 (mars 2021) : 53–59. http://dx.doi.org/10.4028/www.scientific.net/msf.1025.53.
Texte intégralRésumé :
The use of steel in aerospace manufacture continues to decrease, owing in part to the sustainability and mechanical properties of fibers which have higher strength in minimum weight than steel. This study was defined to evaluate the mechanical properties of high-performance fibers, especially aramid, in terms of composite to be part of aircraft' wings called CN-235. The reinforcements were pre-impregnated by the materials manufacturers, under heat and pressure, with a pre-catalysed resin. Then the layering of aramid prepregs was carried with a dry lay-up process and cured in the autoclave at a temperature of 125°C and pressure of 3 bar for 90 minutes. The aramid composite was cured in various grain directions and examined in mechanical tests such as tensile, compression, and interlaminar shear strength tests. The result showed an insignificant difference between 0 and 90 degrees of grain direction in aramid composite in any properties. The strength of aramid composite with 90 degrees of grain direction has a higher value in the compression test (less than 5%) while having lower value in tensile and interlaminar shear tests.
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Chen, Jian Yun, Ming Zhang et Zhi Guang Liu. « Microscopic Numerical Simulation of Reinforced Concrete Damage Evolution under Uniaxial Tension and Compression ». Advanced Materials Research 424-425 (janvier 2012) : 439–42. http://dx.doi.org/10.4028/www.scientific.net/amr.424-425.439.
Texte intégralRésumé :
Based on the mesoscopic random aggregate model and brittle-damage constitutive model, the numerical simulations of tension and compression are performed on reinforced concrete, and the thickness method is employed to simulate the interface between steel bar and concrete. Then a series of samples are generated randomly based on Weibull distribution’ mechanical parameters, and these samples are used to investigate meso damage evolution process of reinforced concrete, as well as the impact of parameter selection on macro-strength characterization of reinforced concrete. The results of numerical simulations effectively reveal the accumulation of tensile damage of meso-units, which lead to the failure of reinforced concrete. In conclusion, this research provides an innovative method to investigate the mechanical properties of interface between steel bar and concrete.
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Hao, Bao Hong, Ju Yi Guo, Ding Zeng et Qi Hui Zeng. « Mechanical Performance Degradation Rule of Deformed Bar under Different Corrosion States ». Applied Mechanics and Materials 532 (février 2014) : 554–57. http://dx.doi.org/10.4028/www.scientific.net/amm.532.554.
Texte intégralRésumé :
This paper will systematically study the different shapes of steels corrosion rate under different corrosion environments through accelerated corrosion test of orthogonal experiment and the corresponding physical tests and electrochemical detection methods. The experimental results show that the corrosion resistance of the deformed bar is poorer than the plain round bar. In the same corrosive environment, its tensile strength, yield strength and elongation decline are more significantly than the round steel, and the change of the elongation is more obvious. Experimental results also show that in the environment which is absence of chloride ion, reinforced is basically with uniform corrosion in previous time, late stage for the development of local corrosion, the mechanics performance index is also present a corresponding positive correlation with the corrosion situation. But the uneven corrosion condition appears at the previous period when it is in the chlorine ion environment. In this condition, the mechanical performance and corrosion situation is no longer in linear relationship, but the trend of rapidly decline. Results of weightlessness rate test confirm that the correlation of degree of corrosion and the mechanical properties.
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Made Budiwati, Ida Ayu, et I. Ketut Sudarsana. « Flexural tests of masonry beam with and without reinforced bar ». MATEC Web of Conferences 276 (2019) : 01018. http://dx.doi.org/10.1051/matecconf/201927601018.
Texte intégralRésumé :
Behaviour of reinforced masonry has been studied experimentally to determine its strength potential. The increase in either compressive or tensile strength of masonry is possible due to the existence of rebar or wire mesh. The research is carried out to determine the effect of steel rebar on flexural strength of reinforced masonry beam using local brick. The square hollow masonry beams of 330x330mm with and without reinforced bar were tested in the laboratory to determine the load and deflection curves and bending strength. The rebar was located at the centre of beam’s cross section and left unbounded. Mechanical properties of masonry’s constitute were also determined. It was found that the flexural strength of beams with rebar of 22 mm diameter was greater 11 times than that of beam without rebar. However, that strength was only 1.6 times due to the weaker end connections of the beam to the rebar. Flexural strength of reinforced masonry beam with 22 mm rebar was greater 2.7 times compared to the beam using a rebar diameter of 16 mm.
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Choi, Yun Cheul, Hyun Ki Choi et Chang Sik Choi. « Experimental Study on Behavior of Flexural Member with Lab-Spliced GFRP Bar ». Key Engineering Materials 452-453 (novembre 2010) : 781–84. http://dx.doi.org/10.4028/www.scientific.net/kem.452-453.781.
Texte intégralRésumé :
The use of glass-fiber-reinforced polymer (GFRP) bars to replace steel reinforcement in concrete structures is a relatively new technique. GFRP bars possess mechanical properties different from steel bars, including high tensile strength combined with low elastic modulus and elastic brittle stress–strain relationship. Therefore, design procedures should account for these properties. This paper presents the experimental moment deflection relations of GFRP reinforced beam which are spliced. Test variables were lab-spliced length of GFRP rebar. A total of 6 concrete beams reinforced with steel and GFRP rebar tested. Three concrete beams reinforced with spliced GFRP rebar and 1 reference beams reinforced with non-spliced GFRP rebar was tested. All the specimens had a span of 4000mm, provided with 12.7mm nominal diameter steel and GFRP rebar. All test specimens were tested under 2-point loads so that the spliced region is subject to constant moment. The experimental results show that the splice length of GFRP increased with the ultimate load increasing and decreased with stiffness.
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Dacuan, Cecielle N., Virgilio Abellana et Hana Astrid Canseco. « Mechanical Properties of Corroded-Damaged Reinforced Concrete Pile-supporting Wharves ». Civil Engineering Journal 6, no 12 (30 novembre 2020) : 2375–96. http://dx.doi.org/10.28991/cej-2020-03091624.
Texte intégralRésumé :
Corrosion is one of the significant deteriorations of reinforced concrete structures. It accelerated the performance loss of the structures, leading to a cross-sectional reduction of steel, which affects its mechanical properties, particularly its tensile capacity and ductility. The purpose of this study is to assess the serviceability and safety of corroded-damaged structures, particularly those exposed to aggressive marine environments. A total of 54 pcs of 150 mm-diameter and 300mm-height of cylindrical specimen were cast. Small-scaled specimens were accelerated to corrosion using impressed current techniques with a constant current density of 200 µA/cm2. Samples were immersed in a simulated environment with a 5% solution of sodium bicarbonate during corrosion acceleration. Corrosion alters the surface configuration of the steel bar. Pitting corrosions due to chloride aggression causes the residual cross-sectional area of corroded rebars to no longer round and varies considerably along its circumference and length. The reduction of the steel cross-sectional area has a significant impact on the degradation of the strength and durability of reinforcing structures. The residual capacity of the corroded reinforcement decreases with the reduction of the cross-sectional area of the steel reinforcement. The rate of corrosion affects the extent of the remaining service life of a corroded reinforced concrete structure. Doi: 10.28991/cej-2020-03091624 Full Text: PDF
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Safi, Seyed Majid, Seyed Yousef Ahmadi Brooghani, Hossein Amirabadi, Khalil Khalili et Mohamad Kazem Besharati Givi. « A Comparison of Tensile Strength and Impact Energy of Austempered versus Step Quenched 4340 Ultra High Strength Steel ». Key Engineering Materials 553 (juin 2013) : 41–45. http://dx.doi.org/10.4028/www.scientific.net/kem.553.41.
Texte intégralRésumé :
This study was conducted to determine if austempered 4340 steel had different mechanical properties compared to step quenched 4340 steel. Tensile strength and impact energy was determined at room temperature under identical test conditions. The specimens were cut from a bar with 25 mm diameter and austenitized at 800°C for 60 min and followed by quenching at 430°C for the high austempering temperature to achieve the upper bainite morphology and at 360°C for the lower austempering temperature to achieve the lower bainite morphology. In the case of step quenched, the specimens were first austempered at 430°C and then austempered at 360°C to achieve the mixed structure of upper bainite and lower bainite morphology. The another set of specimens for step quenching, after austenitization were quenched to below Ms (martensite start temperature), followed by heating at 400°C to achieve the mixed structure of tempered martensite and lower bainite and 500°C to achieve the mixed structure of tempered martensite and upper bainite. It is also shown that the best combination of strength and ductility can be achieved by the mixed structure of tempered martensite and lower bainite that has been suggested in this investigation.
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Yadav, Umesh, et Bhakta Bahadur Ale. « Study on Mechanical Properties of TMT Bars Manufactured in Nepal ». Journal of Advanced College of Engineering and Management 6 (10 juillet 2021) : 245–57. http://dx.doi.org/10.3126/jacem.v6i0.38363.
Texte intégralRésumé :
Three grades of deformed steel bar are presently available in Nepal for concrete reinforcement. The deformed bars are graded according to their specified yield strength. These are Fe415, Fe500 and Fe500D. CTD bars of grade more than Fe415 are scarcely available in market. However, TMT bars of Fe500 grade are easily available in market. This study is undertaken to evaluate the variability of the mechanical properties of reinforcing steel granted with NS Mark and to analyze the degree to which these rolling mills satisfy the minimum requirements established by product national standard NS:191. The data obtained from test results are statistically analyzed to evaluate the variability in the mechanical properties of TMT bars. For the tested mechanical properties, the parameters evaluated for each bar size, and grade at confidence level at 95 % are mean, standard deviation, coefficient of variation, minimum, maximum, skewness. The samples were collected from NBSM reference sample store room of FY 2073-74 and FY 2074-75. These samples were from nineteen industries and twenty-two different brands. Total 745 numbers of TMT bars of grade Fe500 and Fe500D were tested at NBSM mechanical testing laboratory. The mechanical properties determined from the tested samples are: mass per meter run, yield stress, tensile stress, percentage elongation, UTS/YS ratio, total elongation at maximum force, and bond value.The tested data and obtained statistics of different mechanical properties for the separate and combined data takes on an important practical significance and may be used in calibrating local specifications and designs.
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Zhang, Qian, Wenqing Zhang, Yu Fang, Yongjie Xu et Xianwen Huang. « Experimental Study on Mechanical Properties of High Performance Hybrid Fiber Concrete for Shaft Lining ». Applied Sciences 11, no 17 (27 août 2021) : 7926. http://dx.doi.org/10.3390/app11177926.
Texte intégralRésumé :
In order to solve the problem of highly brittle shaft lining under dynamic loading, a combination of hybrid fiber concrete mixed with steel and polypropylene fiber is proposed to make shaft lining. C60, the concrete commonly used in shaft lining, was selected as the reference group. The static mechanical properties, dynamic mechanical properties, and crack failure characteristics of the hybrid fiber concrete were experimentally studied. The test results showed that compared to the reference group concrete, the compressive strength of the hybrid fiber-reinforced concrete did not significantly increase, but the splitting tensile strength increased by 60.4%. The split Hopkinson compression bar results showed that the optimal group peak stress and peak strain of the hybrid fiber concrete increased by 58.2% and 79.2%, respectively, and the dynamic toughness increased by 68.1%. The strain distribution before visible cracks was analyzed by the DIC technology. The results showed that the strain dispersion phenomenon of the fiber-reinforced concrete specimen was stronger than that of the reference group concrete. By comparing the crack failure forms of the specimens, it was found that compared to the reference group concrete, the fiber-reinforced concrete specimens showed the characteristics of continuous and slow ductile failure. The above results suggest that HFRC has significantly high dynamic splitting tensile strength and compressive deformation capacity, as well as a certain anti-disturbance effect. It is an excellent construction material for deep mines under complex working conditions.
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Li, Ke Liang, Zhong Zheng Yang, Guo Hong Huang et Xiu Sheng Tang. « Property of High Volume Industrial Residue Concrete ». Advanced Materials Research 250-253 (mai 2011) : 890–94. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.890.
Texte intégralRésumé :
To protect circumstance and improve of structure durability of Cao’e River floodgate, high volume industrial residue concrete (HVIRC) was prepared, and its mechanical property and durability were studied systematically. 10% of fly ash and 40% of ground granulated blast-furnace slag was used to replace 50% of cement in HVIRC. HVIRC had better anti-carking ability with larger tensile strength, larger ultimate tensile strain, larger tensile-compressive strength ratio and smaller elastic modulus-to-strength ratio. Dry shrinkage rate of HVIRC was similar with that of ordinary Portland concrete (OPC). HVIRC had higher compactness with smaller gas diffusion coefficient and relative permeability coefficient. Expansion caused by alkali-silica reaction reduced greatly by using high volume industrial residue and alkali-silica reaction was controlled markedly. HVIRC had better property of chloride ion penetration resistance with low effective diffusion coefficient. HVIRC could protect steel-bar from premature corrosions. Properties of sulfate resistance and frost resistance of HVIRC were also favorable. It’s proved that high volume industrial residue can enhance greatly mechanical property and durability of concrete and HVIRC can be used in Cao’e River floodgate.
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Toribio, Jesús, Beatriz González et Juan Carlos Matos. « Transient and Steady State Regimes of Fatigue Crack Growth in High Strength Steel ». Key Engineering Materials 525-526 (novembre 2012) : 553–56. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.553.
Texte intégralRésumé :
This paper analyzes the propagation of fatigue cracks in pearlitic steel in two forms, hot rolled bar and cold drawn wire. The experimental procedure consisted of fatigue tests on bars under tensile loading, using steps with decreasing amplitude of stress and constant stress range during each step. The curves plotting cyclic crack growth rate versus stress intensity factor range show a main steady-state regime preceded by transient paths. The steady-state regime is associated with the curves of the Paris regime. The cold drawing process improves the fatigue behaviour of steel by retarding the cyclic crack growth rate, and the propagation rate is not dependent on theR-ratio. The transient branches allow one to calculate the plastic zone size, considering that they are a consequence of the overload retardation effect at each step change, and a unique expression is fitted as a function ofKmaxΔKproduct and of the conventional mechanical properties.
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Machado, Juliana de Carvalho, Cristiane Duque, Josânia Pitzer de Oliveira et Angela Scarparo Caldo-Teixeira. « Effect of storage time and chlorhexidine addition on the mechanical properties of glass ionomer cements ». Brazilian Journal of Oral Sciences 16 (15 décembre 2017) : 1–9. http://dx.doi.org/10.20396/bjos.v16i0.8650457.
Texte intégralRésumé :
Aims: To evaluate the effect of the chlorhexidine (CHX) incorporation and the storage time on the mechanical properties of glass ionomer cements (GICs). Methods: The following GICs were evaluated: Ketac Molar Easymix (KM), Vidrion R (VR) and Vitromolar (VM), containing or not CHX. GIC liquid was modified by adding 1.25 % CHX digluconate and then manipulated with the power and placed into the stainless steel cylindrical or bar-shaped molds. GICs specimens were stored into water for 1, 7 and 28 days. After these periods, specimens were submitted to flexural, diametral tensile and compressive strength tests, according to ISO standards. Data from mechanical tests were statistically analyzed using 2-way ANOVA and Tukey tests. Results: Overall, the storage time did not influence any of the mechanical properties of the GICs tested. In contrast, the inclusion of CHX reduced significantly these properties for all GICs tested. KM presented the highest values of compressive strength for all storage times. KM + 1.25% CHX had lower compressive strength results than KM, however, it showed similar results when compared to another GICs without CHX. Conclusions: The presence of chlorhexidine, independent of the storage time, interfered on the mechanical characteristics of GIC.
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Odnobokova, Marina, Andrey Belyakov, Alla Kipelova et Rustam Kaibyshev. « Formation of Ultrafine-Grained Structures in 304L and 316L Stainless Steels by Recrystallization and Reverse Phase Transformation ». Materials Science Forum 838-839 (janvier 2016) : 410–15. http://dx.doi.org/10.4028/www.scientific.net/msf.838-839.410.
Texte intégralRésumé :
The microstructure evolution and mechanical properties of 316L and 304L austenitic stainless steels subjected to large strain cold bar rolling and subsequent annealing were studied. The cold working was accompanied by mechanical twinning and strain-induced martensitic transformation. The latter was readily developed in 304L stainless steel. The uniform microstructures consisting of elongated austenite and martensite nanocrystallites evolved at large total strains, resulting in tensile strength above 2000 MPa in the both steels. The subsequent annealing at temperatures above 700°C was accompanied by the martensite-austenite reversion followed by recrystallization, leading to ultrafine grained austenite.
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He, Huan An, et Cheng Kui Huang. « Study on Restrained Expansive Deformation of Steel Fiber Reinforced Self-Stressing Concrete ». Key Engineering Materials 385-387 (juillet 2008) : 305–8. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.305.
Texte intégralRésumé :
A new sort of high performance concrete is introduced which combines most advantages of prestressed concrete and steel fiber concrete, named steel fiber reinforced self-stressing concrete(SFFRSSC for short). Self-stressing concrete is actually a kind of expansive concrete which self-stresses, namely pre-compressive stresses, are induced by dint of some restrictions generally provided by steel bars to concrete expansion after hydration of expansive cement. As a result of chemical reaction, concrete archived prestresses by itself different from mechanical prestressed concrete, so called self-stressing concrete. By distributing short-cut steel fibers into self-stressing concrete at random, prestresses( self-stress) are created in concrete under combined restriction of steel bars and steel fibers. Thank to the pre-stresses tensile strength of concrete are significantly increased as well as cracking strength. In addition, expansive deformation of SFFRSSC can compensate the shrinkage of concrete to decrease shrinkage crack, and the steel fibers play an important role in post-crack behavior. On the other hand, self-stressing concrete can avoid the troubles of construction compared with conventional mechanical prestressed concrete. For purpose of understanding the properties of SFFRSSC, in this paper some researches were carried out to investigate the special expansive behaviors of restrained expansive deformation with restriction of steel bar as well as steel fiber. The test results indicated that steel bar and steel fiber both provide effective restrict to self-stressing concrete as result of forming prestresses in concrete.
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Sripada, Jagannadh V. S. N., Megil F. Gallant, Gobinda C. Saha, Reeti Singh et Jan Kondas. « Tantalum Based High-Pressure Cold Spray Coatings on Stainless Steel Substrate ». Key Engineering Materials 813 (juillet 2019) : 429–34. http://dx.doi.org/10.4028/www.scientific.net/kem.813.429.
Texte intégralRésumé :
Tantalum as a transition element possesses good corrosion resistant properties, along with ductility and hardness. It is also one of the best heat-resistant material (melting point 2996°C) and is known for its high heat and electrical conductivity. In this research, Tantalum is deposited on stainless steel substrate using high-pressure cold spray (HPCS) method. Cold spray coating technology enables the deposition of powder feedstock without melting. Feedstock particles are propelled through a nozzle at supersonic velocities and they deform plastically on impact, resulting in good bonding strength to the substrate. The low temperature and solid-state deposition associated with cold spray allows refractory materials such as Ta, Mo, and W to be deposited without high temperature requirements. The objective of this work is to achieve a dense and nonporous coating microstructure with a high deposition efficiency. The hardness of as-received tantalum particles is found to be 279 HV0.3 and the microstructure is very dense. Tensile testing carried on the sample coated at a stagnation gas pressure of 50 bar and gas inlet temperature of 900°C exhibited an ultimate tensile strength of 442 MPa and adhesion strength of 77 MPa. Further mechanical properties of the coating in terms of hardness is carried out by nanoindentation. These results will be correlated with microstructural imaging and elemental analysis including morphology and composition using scanning electron microscopy and X-ray diffraction techniques.
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Jhatial, Ashfaque Ahmed, Aamir Khan Mastoi, Zafar Ali Siyal, Touqeer Ali Rind et Imtiaz Ahmed Memon. « Influence of Long Polypropylene Fibre on the Properties of Concrete ». Quaid-e-Awam University Research Journal of Engineering, Science & ; Technology 18, no 02 (31 décembre 2020) : 38–43. http://dx.doi.org/10.52584/qrj.1802.06.
Texte intégralRésumé :
Concrete is the most used building and construction material globally due to the ease of availability and durability. It is a well-known fact that concrete can easily withstand compressive stresses; however, it fails under tension. To improve this deficiency, steel bar reinforcement has been used. However, with the steel reinforcement, additional permanent self-weight is transferred on the structure and is prone to corrosion. Hence, engineers and researchers have been working to search for more sustainable reinforcing material that could be cost-effective and simultaneously increase tensile strength. This experimental work was carried out to study the influence of long (38.1 mm) polypropylene (PP) fibres on the workability and mechanical strengths (compressive and flexural) of concrete. Three different fibre fraction content, 0.20%, 0.25% and 0.30% were selected to reinforce concrete. A total of 12 cylinders of 300mm×150mm dimension (3 cylinders per mix) and 12 beams of 609.6mm×304.8mm×101.6mm dimension (3 beams per mix) were used to determine the compressive strength and flexural strength after the samples achieved 28 days curing. Based on the results, it can be observed that longer fibres do not significantly influence the compressive strength as much as they do on flexural strength. Furthermore, longer length fibres, like shorter fibres, obstruct the workability of concrete. Comparing with previous findings, it can be concluded that for patching of macrocracks, longer length PP fibres should be used.
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Ogrodowska, Karolina, Karolina Łuszcz et Andrzej Garbacz. « The effect of temperature on the mechanical properties of hybrid FRP bars applicable for the reinforcing of concrete structures ». MATEC Web of Conferences 322 (2020) : 01029. http://dx.doi.org/10.1051/matecconf/202032201029.
Texte intégralRésumé :
One of the most common causes of the deterioration of concrete structures is the corrosion of steel reinforcement. Reinforcement made from fiber reinforced polymers (FRP) is considered to be an attractive substitution for traditional reinforcement. The most popular FRP reinforcing bars are made of glass fibers. Basalt fiber reinforced polymer (BFRP) is a relatively new material for reinforcing bars. The main drawback of BFRP bars is their low modulus of elasticity. A new type of bar made from hybrid fiber reinforced polymer (HFRP) in which a proportion of the basalt fibers are replaced with carbon fibers can be considered as a solution to this issue; such a bar is presented in this work. The HFRP bars might be treated as a relatively simple modification to previously produced BFRP bars. A different technical characteristic of the fibre reinforced polymer makes the designing of structures with FRP reinforcement differ from conventional reinforced concrete design. Therefore, it is necessary to identify the differences and limitations of their use in concrete structures, taking into account their material and geometric features. Despite the predominance of FRP composites in such aspects as corrosion resistance, high tensile strength, and significant weight reductions of structures – it is necessary to consider the behavior of FRP composites at elevated temperatures. In this paper, the effect of temperature on the mechanical properties of FRP bars was investigated. Three types of FRP bar were tested: BFRP, HFRP in which 25% of basalt fibers were replaced with carbon fibers and nHFRP in which epoxy resin was additionally modified with a nanosilica admixture. The mechanical properties were determined using ASTM standard testing for transverse shear strength. The tests were performed at -20°C, +20°C, +80°C for three diameters of each types of bar.
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Salleh, Norhafizah, Abdul Rahman Mohd Sam, Jamaludin Mohd Yatim et Mohd Firdaus bin Osman. « Flexural Behaviour of Reinforced Concrete Beam with Glass Fiber Reinforced Polymer (GFRP) Bar Strengthened with Carbon Fiber Reinforced Polymer (CFRP) Plate ». Advanced Materials Research 1051 (octobre 2014) : 748–51. http://dx.doi.org/10.4028/www.scientific.net/amr.1051.748.
Texte intégralRésumé :
The use of glass-fiber-reinforced polymer (GFRP) bar to replace steel reinforcement in concrete structures is a relatively a new technique. The GFRP bars possess mechanical properties different from steel bars, including high tensile strength combined with low elastic modulus and linear stress–strain relationship up to failure. Therefore, design procedures and process should account for these properties. This paper presents the experimental work on the flexural behavior of concrete beam reinforced with GFRP bars and strengthen with CFRP plate. A total of ten reinforced concrete beams reinforced with either steel and GFRP bars were cast and tested under four point loads. Eight concrete beams (200x250x2800mm) were reinforced with 13mm diameter GFRP bars together with strengthening using CFRP plate and two control beams reinforced with 12mm diameter steel bars were tested. The experimental results show that although the stiffness of the beams reduced but the ultimate load of the GFRP reinforced concrete beam is bigger than steel reinforced beam. It was also found that strengthening using CFRP plate will further enhanced the flexural performance of the beams with GFRP bars.
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Liu, Zhen Bao, Jian Xiong Liang, Xiu Li Zhang, Zhi Yong Yang et Guo Qiang Sun. « The Development and Application of High-Performance Ultra-High Strength Stainless Steel Subject to Marine Environment ». Materials Science Forum 783-786 (mai 2014) : 867–74. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.867.
Texte intégralRésumé :
An alloy chemical composition of a new ultra-high strength stainless has been successfully designed through strengthening mechanisms of carbide and intermetallic compounds. The forging round bar with diameter of 200 mm has been manufactured by means of ultra-high purity smelting and the whole process technologies of micro-unit refinement and phase change control. It was revealed that the developed steel assumes tensile strength of 1960MPa, elongation of 13.5%, fracture toughness KICgreater than 90MPa·m1/2, and KISCCgreater 60MPa·m1/2. Based on the microstructural observation and phase identification, it was found that the M2C and the Laves phase were precipitated in the martensitic laths and a small amount of austenite phase was retained in between the Martensitic lath interfaces, which were related to the improved strength and toughness of the developed steel. Furthermore, it was indicated that the steel also presents high fatigue properties and good high-temperature mechanical properties. The corrosion resistance of the steel is equivalent to that of 15-5PH stainless steel but much better than that of the Aermet100 steel under the condition of the marine atmosphere and sea water immersion. This developed steel can be applied in marine corrosive environment without the surface protection and thus can save the expensive maintenance costs and avoid environmental pollution. Based on the promising properties, it was concluded that the developed steel has wide application prospects in the fields of aviation, aerospace, ships, advanced machinery, and advanced machinery manufacturing and other high-tech.
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Liu, Mu Tong, Ping Zhong, Wei Sheng et Zhen Ye Zhao. « Optimized Design of Ultra-High Strength Stainless Steel Based on Thermo-Calc Calculation ». Materials Science Forum 993 (mai 2020) : 585–91. http://dx.doi.org/10.4028/www.scientific.net/msf.993.585.
Texte intégralRésumé :
The thermodynamic calculation software Thermo-Calc was used to study the influences of alloy elements Cr, Co, and Mo on the precipitated phases of a S280 ultrahigh strength stainless steel at the temperatures ranging from 400 °C to 1200 °C. The results showed that the precipitated phases in the steel were mainly composed of M23C6 carbide, M6C carbide, intermetallic compound of Laves phase and σ phase. The temperature and the content change of alloying elements Cr, Co and Mo have little effect on the precipitation of M23C6 carbide, while have great effect on the precipitation of Laves phase and σ phase. By lowering the element content and adjusting the heat treatment temperature, the precipitation of σ phase in the alloy can be reduced．According to the results of thermodynamic simulation, after optimizing the chemical composition, the Ф300mm bar was trial-produced. The chemical composition, microstructure and mechanical properties of the alloy were analyzed and tested. The results show that, after tempering at 550 °C, the main precipitated phases in the S280 alloy were M23C6 carbide and intermetallic compound of Laves phase. The characterized nano-precipitates have good agreement with simulation results. The optimized design of S280 steel reached a tensile strength over 1930 MPa and a fracture toughness of 90 MPa•m1/2.
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Van Slycken, Joost, Jérémie Bouquerel, Patricia Verleysen, Kim Verbeken, Joris Degrieck et Yvan Houbaert. « Static and Impact-Dynamic Characterization of Multiphase TRIP Steels ». Materials Science Forum 638-642 (janvier 2010) : 3585–90. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.3585.
Texte intégralRésumé :
In this study, results are presented of an extensive experimental program to investigate the strain rate dependent mechanical properties of various Transformation Induced Plasticity (TRIP) steel grades. A split Hopkinson tensile bar setup was used for the high strain rate experiments and microstructural observation techniques such as LOM, SEM and EBSD revealed the mechanisms governing the observed behavior. With elevated testing temperatures and interrupted tensile experiments the material behavior and the austenite to martensite transformation is investigated. In dynamic conditions, the strain rate has limited influence on the material properties. Yet an important increase is noticed when comparing static to dynamic conditions. The differences in strength, elongation and energy absorption levels observed between the investigated materials can be attributed to their chemical composition. Adiabatic heating during high strain rate deformation tends to slow down the strain induced martensitic deformation. The elongation of the ferritic and austenite constituents is found to be strain rate dependent and the strain induced martensitic transformation occurs gradually in the material.
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Sergeev, N. N., A. N. Sergeev, S. N. Kutepov, I. V. Tikhonova, A. E. Gvozdev, E. V. Ageev et D. S. Klement'yev. « Influence of Charge Quality on Physical, Mechanical and Operational Properties of Low-Alloy Steel 30KHGSA ». Proceedings of the Southwest State University 24, no 2 (4 octobre 2020) : 17–36. http://dx.doi.org/10.21869/2223-1560-2020-24-2-17-36.
Texte intégralRésumé :
Purpose of reseach is to study the influence of the quality of the original charge on the complex of physical, mechanical and operational properties of structural low-alloy steel 30HGSA.Methods. As an object of research, a typical representative of low-alloy structural steels has been chosen - steel 30HGSA, smelted using metallized sponge iron pellets, ordinary scrap metal and billets obtained by the method of a boiling slag layer. In accordance with the set objectives of the study, steel 30HGSA of various melts, obtained with different charge, had the same conditions for melting, evacuation, deoxidation, casting and crystallization. The casting temperature was 1600...1620 оC and the post-vacuum treatment temperature was 1530...1560 °C. Duration of evacuation - 5 minutes. Casting of melts was carried out into cast iron molds with a siphon for 4 ... 5 minutes. Deoxidation was carried out in a ladle with aluminum in the amount of 4 ... 4.5 kg / melt. After solidification, the ingots were cooled in special wells. The ingots were cut into 3 parts: head, middle and bottom (600 × 600 mm). The middle part was then hot forged and rolled to a Ø30 mm bar. The length of the rod was 2 ... 3.4 m. After hot deformation, the rods were cooled in air.Results. Mechanical tests have been carried out. Statistical processing of experimental results has been performed. Regularities of changes in the characteristics of mechanical properties have been revealed: tensile strength, creep strength, relative narrowing of the cross-sectional area of the sample, relative elongation of the initial working length, impact strength (σВ, σ0.2, ψ, δ, aН).Conclusion. It has been found that with an increase in temperature, the mechanical properties of steel 30HGSA, smelted on various charges, decrease. It has been established that the cold brittleness threshold of 30HGSA steel is lower for purer melts on spongy iron and intermediate product KShS, the value of impact toughness at low temperatures is higher than in melting on a conventional metallized charge. Noticeable softening begins at a tempering temperature of 300 °C The temperature of the maximum tempering brittleness for steel 30HGSA, melted on a conventional metallized charge, is 550 °C It is shown that steel 30HGSA smelted with a pure original charge (spongy iron) has a lower tendency to temper brittleness than steel smelted with a conventional charge. The value of the impact toughness of the steel of this melt is higher than that of the steel of conventional melting over the entire tempering temperature range.
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Khamichonok, V. V., N. G. Matveev, I. A. Mirochnik et E. V. Chinоikalov. « Elaboration of a technology of class A500 reinforcing bar production with a complex of additional properties as per GOST 34028–2016 at JSC EVRAZ ZSMK ». Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 75, no 6 (26 juillet 2019) : 711–17. http://dx.doi.org/10.32339/0135-5910-2019-6-711-717.
Texte intégralRésumé :
On 01.01.2019 the interstate standard GOST 34028–2016 “Reinforcing bars for concrete structures. Technical specifications” will come into force, which will replace the standards GOST R 52544 (in the part of A500S class), GOST 10884 and GOST 5781. The new standard will introduce a complex of additional properties for reinforcing bars of A500 class to provide reliability of its application in the high rise construction, in areas of increased seismic activity, in aggressive media (sea areas) and in bridges construction (increased cyclic loads). In view of this a complex of work accomplished at JSC EVRAZ ZSMK to elaborate technologies of production A500 reinforcing bars, completely meeting the requirements of GOST 34028 regarding base characteristics (tensile strength, yield strength, elongation, technological ductility) as well as additional ones (corrosion resistance, endurance, high ductility). In addition, an evaluation of fire resistance and fire safety of the A500 class rebar (the characteristics not present in the standard) accomplished. To determine the additional characteristics the following tests done: for tensile and bending for rebar of high ductility (class A500E), for corrosion resistance (class A500K), for endurance (class A500У), for fire resistance and fire safety (class А500С and А500Е). As a result of the work accomplished it was determined, that reinforcing bars of trial production of 18Г2С steel, micro-alloyed by vanadium, meet the requirements of GOST 34028–2016 to A500E class. Also determined that the reinforcing bars of trial production of class А500К and А500Е, made of steel grades Ст3Гпс, Ст3Гсп and 18Г2С meet the requirements of GOST 34028 regarding corrosion resistance for their application in structures without preliminary strain. Besides it was shown, that the reinforcing bars of regular production made of Ст3пс and Ст3Гсп steel grades meet the requirements of GOST 34028–2016 to class A500У regarding to resistance against fatigue multiple repeating cyclic loads. The experiment data regarding the fire resistance and fire safety obtained for trial and regular production enabled to determine the heating temperature effect on the rebar mechanical properties depending on the steel chemical composition and the bar diameter.