Journal articles: 'Bainitic steel – Mechanical properties'

1

Ansari, M. H. Sheikh, and M. Aghaie-Khafri. "Investigation of Microstructure and Mechanical Properties of Ultra High Strength Bainitic Steel." Applied Mechanics and Materials 313-314 (March 2013): 77–81. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.77.

Full text

Abstract:

In this study, medium carbon low alloy steel was used to obtain bainitic structures. The lower bainite and tempered martensite-lower bainite structures were achieved by isothermal austempering and up quenching treatment, respectively. Based on the results obtained these structures showed a very good combination of strength and toughness. Furthermore, it has been shown that austenitization time and temperature, as well as austempering time and temperature play a major role in achieving ultra-high strength bainitic steels.

APA, Harvard, Vancouver, ISO, and other styles

2

Wang, Ke Lu, Xin Li, and Xian Juan Dong. "Effect of Tempering Temperature on Mechanical Properties and Microstructures of 800MPa Microalloy Low Carbon Bainitic Steel." Advanced Materials Research 893 (February 2014): 406–9. http://dx.doi.org/10.4028/www.scientific.net/amr.893.406.

Full text

Abstract:

The effect of tempering temperature on the microstructures and mechanical properties of a microalloy low carbon bainitic steel was investigated by microscopic analysis and testing of mechanical properties. The results show that the microstructures of the tested steel primarily consists of lath bainite, granular bainite, quasipolygonal ferrite and little acicular ferrite at different tempering temperatures. With the tempering temperature increasing, the proportion of lath bainitie decreases, while the volume of granular bainite and quasipolygonal ferrite increases. At the tempering temperatures of 550-650°C and tempering time of 1 hour, the steel was mostly composed of granular bainite, quasipolygonal ferrite and a little lath bainite, which a good combination of strength and toughness can be obtained.

APA, Harvard, Vancouver, ISO, and other styles

3

Guo, Hui, Xianying Feng, Aimin Zhao, Qiang Li, and Jun Ma. "Influence of Prior Martensite on Bainite Transformation, Microstructures, and Mechanical Properties in Ultra-Fine Bainitic Steel." Materials 12, no. 3 (February 12, 2019): 527. http://dx.doi.org/10.3390/ma12030527.

Full text

Abstract:

A multiphase microstructure comprising of different volume fractions of prior martensite and ultra-fine bainite (bainitic ferrite and retained austenite) was obtained by quenching to certain temperatures, followed by isothermal bainitic transformation. The effect of the prior martensite transformation on the bainitic transformation behavior, microstructures, and mechanical properties were discussed. The results showed that the prior martensite accelerated the subsequent low-temperature bainite transformation, and the incubation period and completion time of the bainite reaction were significantly shortened. This phenomenon was attributed to the enhanced nucleation ratio caused by the introduced strain in austenite, due to the formation of prior martensite and a carbon partitioning between the prior martensite and retained austenite. Moreover, the prior martensite could influence the crystal growth direction of bainite ferrite, refine bainitic ferrite plates, and reduce the dimension of blocky retained austenite, all of which were responsible for improving the mechanical properties of the ultra-fine bainitic steel. When the content of the prior martensite reached 15%, the investigated steels had the best performance, which were 1800 MPa and 21% for the tensile strength and elongation, respectively. Unfortunately, the increased content of the prior martensite could lead to a worsening of the impact toughness.

APA, Harvard, Vancouver, ISO, and other styles

4

Yang, Xiao Long, Yun Bo Xu, Xiao Dong Tan, Yong Mei Yu, and Di Wu. "Microstructures and Mechanical Properties of High Strength Low Carbon Bainitic Steel." Materials Science Forum 817 (April 2015): 257–62. http://dx.doi.org/10.4028/www.scientific.net/msf.817.257.

Full text

Abstract:

Based on TMCP and UFC technology, the microstructures and mechanical properties of 0.05% C bainitic steel were studied in this paper. The bainite morphology and precipitation within bainite lath were observed by SEM and TEM, and the mechanical properties of bainitic steel were measured by tensile and impact test. The results showed that the yield and tensile strengths of steel were 713 MPa and 891 MPa respectively, and the elongation was 15.8% with impact energy of 95J at the temperature of-20°C as the final cooling temperature in hot rolling of 550°C. For comparison, the steel obtained the yield strength of 725 MPa, tensile strength of 930 MPa and elongation of 18% as the final cooling temperature of 450°C. However, the impact energy of steel was 195J at the temperature of-20°C. While at the same final cooling temperature of 450°C, the fast cooling-holding temperature-fast cooling was applied to experimental steel with a faster cooling rate of 50°C/s, hence the steel acquired the yield strength of 845 MPa, tensile strength of 1037 MPa, and elongation of 15.5% with impact energy of 168J at the temperature of-20°C. The strength and toughness of 0.05%C bainitic steel is related to the bainite morphology and precipitation distribution. Hence, the strength and toughness can be improved by control the different cooling processes for adjusting the content of lath bainite, distribution of granular bainite and precipitation.

APA, Harvard, Vancouver, ISO, and other styles

5

Tressia, Gustavo, Luis H. D. Alves, Amilton Sinatora, Helio Goldenstein, and Mohammad Masoumi. "Effect of bainitic transformation on the microstructure and wear resistance of pearlitic rail steel." Industrial Lubrication and Tribology 72, no. 9 (October 20, 2020): 1095–102. http://dx.doi.org/10.1108/ilt-07-2019-0282.

Full text

Abstract:

Purpose The purpose of this study is to develop a lower bainite structure consists of a dispersion of fine carbide inside plates of bainitic ferrite from chemical composition unmodified conventional pearlitic steel under bainitic transformation and to investigate its effect on tensile properties and wear resistance. Design/methodology/approach A commercial hypereutectoid pearlitic rail steel was subjected to three different bainitic transformation treatments followed by tempering to develop a desirable microstructure with a DIL805 BÄHR dilatometer. A comprehensive microstructural study was performed by scanning electron microscopy and energy dispersive x-ray spectroscopy. Finally, the mechanical properties and wear resistance were evaluated by tensile, microhardness, and pin-on-disc tests. Findings The results showed that the best combination of mechanical properties and sliding wear resistance was obtained in the sample subjected to bainitic transformation at 300°C for 600 s followed by tempering at 400°C for 300 s. This sample, which contained a bainitic ferrite structure, exhibited approximately 20% higher hardness and approximately 53% less mass loss than the as-received pearlitic sample due to the mechanically induced transformation in the contact surface. Originality/value Although pearlitic steel is widely used in the construction of railways, recent studies have revealed that bainitic transformation at the same rail steels exhibited higher wear resistance and fatigue strengths than conventional pearlitic rail at the same hardness values. Such a bainitic microstructure can improve the mechanical properties and wear resistance, which is a great interest in the railway industry. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2019-0282/

APA, Harvard, Vancouver, ISO, and other styles

6

Liu, Zhi Xue, and Ju Qiang Cheng. "Microstructure and Mechanical Properties of New Type Bainitic Carburized Steel for Gear." Advanced Materials Research 602-604 (December 2012): 300–304. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.300.

Full text

Abstract:

This paper presents the microstructure, mechanical properties and carburized behavior of new type bainitic carburized steel. The results show that after new carburized steel is normalized at 920°C and tempered at 300°C, its microstructure consists of bainitic ferrite and residual austenite, and belongs to the carbide-free bainite or atypical bainite. Large or small cross-section size new carburized steel bar all have reached the performance requirements of Cr-Ni carbonized steel. The microstructure of new carburized steel surface consists of high carbon martensite and residual austenite after carburized and air-cooled, It retains austenite fraction of the new carburized steel and 18Cr2Ni4WA steel are about 18% and 38%, respectively. Carbon concentration gradient of new carburized steel changes smoothly and have ideal carbon concentration distribution. Effective carburizing surface depth of new carburized steel is about 0.6mm and is smaller than 18Cr2Ni4WA steel. The gear entities made of new carburized steel meet the technical requirements of heavy duty carburized gear.

APA, Harvard, Vancouver, ISO, and other styles

7

Zhang, Zhan Ling, Ke Ke Zhang, Yun Yue, Ning Ma, and Zhi Wei Xu. "Microstructure and Mechanical Properties of Austempered Ultrahigh Carbon Steel 1.4%C." Materials Science Forum 682 (March 2011): 97–101. http://dx.doi.org/10.4028/www.scientific.net/msf.682.97.

Full text

Abstract:

An ultrahigh carbon steel alloy containing 1.4 wt pct carbon (UHCS-1.4C) was studied. The steel was processed into ultrafine grain and fully spheroidized microstructure through a controlled rolling and controlled-cooling divorced eutectoid transformation, and was then given austempering treatment to form bainite. The mechanical properties of the heat-treated steel were evaluated by tension tests at room temperature. After austenitized at 850 °C and then austempered at 300 - 350 °C, the microstructure was ultrafine upper bainite, retained austenite, and unsolvable cementite. It was shown that the ultimate tensile strengths of UHCS-1.4C ranged from 1420 to 1830 MPa, elongations to failure from 6 to 14%; the ultimate tensile strength increases with decreasing austempering temperature, while the tensile ductility decreases. The fracture surface of bainitic UHCS-1.4C consists mainly of dimples and voids, which reveal a ductile fracture. The present results indicate that ultrahigh carbon steel can be easily processed to achieve bainitic microstructures and unique properties.

APA, Harvard, Vancouver, ISO, and other styles

8

Santacruz-Londoño, Andrés Felipe, Oscar Rios-Diez, José A. Jiménez, Carlos Garcia-Mateo, and Ricardo Aristizábal-Sierra. "Microstructural and Mechanical Characterization of a Nanostructured Bainitic Cast Steel." Metals 10, no. 5 (May 8, 2020): 612. http://dx.doi.org/10.3390/met10050612.

Full text

Abstract:

Nanoscale bainite is a remarkable microstructure that exhibits a very promising combination of high strength with good ductility and toughness. The development of these types of microstructures has been focused on wrought materials, and very little information is available for steel castings. In this work, a specially designed cast steel with 0.76 wt % C was fabricated, and the heat treatment cycles to develop bainitic nanostructures were determined by studying the kinetics of the bainitic transformation using high-resolution dilatometry. The effects of isothermal holding temperature and time on the final microstructure and mechanical properties were thoroughly characterized in order to evaluate a future industrial implementation of the process in an effort to contribute to enhance and widen the potential applications for cast steels.

APA, Harvard, Vancouver, ISO, and other styles

9

Feng, Chun, Bing Zhe Bai, and Yan Kang Zheng. "Effect of 0.06%Nb on the Microstructure and Mechanical Properties of Mn-Series Low Carbon Air-Cooling Bainitic Steels." Advanced Materials Research 284-286 (July 2011): 1191–95. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.1191.

Full text

Abstract:

The effect of 0.06%Nb on the microstructure and mechanical properties of grain boundary allotriomorphic ferrite (FGBA) / granular bainite (Bg) air-cooling bainitic steels has been investigated in this paper. The results indicate that the steel acquires superior mechanical properties by adding 0.06%Nb. Compared with Non-Nb steel, the addition of 0.06%Nb increases the tensile strength and yield strength about 37.1% (From 780MPa to 1070MPa)and 26.6%(From 557MPa to 705MPa) respectively, remaining 18.3% elongation and 97J toughness. The addition of 0.06%Nb not only promotes the nucleation of intragranular ferrite but also refines the allotriomorphic ferrite grain , both of which in turn contribute to the refinement of granular bainite cluster including its ferrite platelets and M-A islands. Under the synthetic roles of the microstructure refinement and precipitation strengthening, 148MPa yield strength improvement has been acquired in the low carbon air-cooling bainitic steel by the adding of 0.06%Nb.

APA, Harvard, Vancouver, ISO, and other styles

10

Zhu, Jiaqi, Zhunli Tan, Yu Tian, Bo Gao, Min Zhang, Junxiang Wang, and Yuqing Weng. "Effect of Tempering Temperature on Microstructure and Mechanical Properties of Bainitic Railway Wheel Steel with Thermal Damage Resistance by Alloy Design." Metals 10, no. 9 (September 10, 2020): 1221. http://dx.doi.org/10.3390/met10091221.

Full text

Abstract:

Thermal damage is one of the principle modes of wagon railway wheels. A new bainitic railway wheel steel with high thermal damage resistance and good combination of strength, plasticity, and toughness was developed. Microstructure and mechanical properties of the new steels in a tempered condition at different temperatures were examined. Microstructures were observed using scanning electron microscope and transmission electron microscope. Mechanical properties were evaluated by tensile, hardness, and Charpy impact tests with a simultaneous comparison to pearlitic railway wheel steel. The characteristic of retain austenite and V(C,N) were measured through X-ray diffractometry and energy disperse spectroscopy. The results indicate that this new bainitic wheel steel presents a submicron-sized carbide-free bainite morphology and preferable integrated mechanical properties when tempered at 280–360 °C. Precipitation strengthening plays an important role for the high strength, since a two-time-strengthening mechanism of the yield strength led by precipitation has been found at 280–360 and 480–560 °C, respectively. Compared with a pearlitic railway wheel steel, bainitic wheel steel tempered at 320 °C has a 10% higher yield strength, five times higher impact toughness, and much better thermal damage resistance, which is a promising railway wheel material for higher speed or heavier axle-load service conditions.

APA, Harvard, Vancouver, ISO, and other styles

11

Boonsukachote, Patiphan, Saranya Kingklang, and Vitoon Uthaisangsuk. "Modelling of Mechanical Properties of Pearlitic Rail Steel." Key Engineering Materials 798 (April 2019): 3–8. http://dx.doi.org/10.4028/www.scientific.net/kem.798.3.

Full text

Abstract:

Railway has become more essential for both mass and goods transportation so that the rails are required to carry higher loads and exhibit longer lifetime. Thus, mechanical properties, especially strength and toughness of rail steel must be continuously increased. In the present work, microstructure, tensile properties and impact toughness of a pearlitic rail steel grade 900A were firstly characterized. It was found that the investigated steel showed high yield and tensile strengths, but moderate elongation. Subsequently, representative volume elements (RVE) model was employed to investigate the effects of bainitic phase on mechanical properties of pearlitic rail steels. The flow stress curves of the individual phases were defined with regard to the chemical composition. As a result, the relationships between predicted yield strengths and tensile strengths in dependence on the phase fraction of bainite were provided. The model can be used to identify the proper microstructure characteristic of rail steel.

APA, Harvard, Vancouver, ISO, and other styles

12

Sourmail, Thomas, Véronique Smanio, Francisca García Caballero, J. Cornide, C. Capdevilla, and Carlos García-Mateo. "Evolution of Microstructure and Mechanical Properties during Tempering of Continuously Cooled Bainitic Steels." Materials Science Forum 706-709 (January 2012): 2308–13. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2308.

Full text

Abstract:

With the increasing demand for high performance engine or suspension components, bainitic steels are receiving interest as potential replacement of their quench and tempered counterparts. Indeed, for a number of mechanical components, ferrite pearlite microstructures are no longer sufficient in terms of mechanical properties. Bainitic steel grades allow production of hot-rolled bars or forged components exhibiting a homogeneous bainitic microstructure and achieving UTS up to 1200 MPa without the need for additional heat-treatments [1]. During tempering, these V-microalloyed bainitic steels exhibit unusual yield strength variations, with a very pronounced increase around 250-300 °C followed by the better known secondary hardening peak for temperatures around 600-650 °C. Indeed, after tempering at 250-300 °C, some of these steels exhibit an increase in yield strength of up to 200 MPa, concurrent with an increase in impact toughness of up to 25%. This, however, goes unnoticed if hardness measurements are used to characterize tempering. In the following, results are presented for three different bainitic steel grades, and the origins of the changes in mechanical properties are discussed.

APA, Harvard, Vancouver, ISO, and other styles

13

Kučerová, Ludmila, Martin Bystrianský, and Josef Káňa. "The Effect of Isothermal Hold Temperature on Microstructure and Mechanical Properties of TRIP Steel." Solid State Phenomena 270 (November 2017): 253–57. http://dx.doi.org/10.4028/www.scientific.net/ssp.270.253.

Full text

Abstract:

TRIP (transformation induced plasticity) steels are low alloyed low carbon steels with complex microstructures consisting of ferrite, bainite and retained austenite. This complex microstructure provides them with excellent strength to ductility balance, making them a member of advanced high strength steels (AHSS) group. Suitable microstructure can be obtained by either heat or thermo-mechanical treatment. A hold in bainite transformation region is an integral part of any form of commercial TRIP steel processing route, as it enables formation of sufficient volume fraction of bainite and also stabilization of retained austenite in the final microstructure. Various bainitic hold temperatures ranging from 350 °C to 500 °C were tested within thermo-mechanical treatment of 0.2C-1.5Mn-0.6S-1.5Al steel and the final microstructures were evaluated with regard to the suitability to TRIP effect and achieved mechanical properties. The microstructures were analyzed by scanning electron microscopy and mechanical properties measured by tensile test.

APA, Harvard, Vancouver, ISO, and other styles

14

Zuo, Long Fei, Zhan Lei Wei, Ri Ni, Ben Ma, and Zi Dong Wang. "Effect of Aging Temperature on the Microstructure and Mechanical Properties of 1000MPa Grade Low Carbon Bainitic Steel." Applied Mechanics and Materials 152-154 (January 2012): 376–80. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.376.

Full text

Abstract:

A kind of 1000MPa low carbon bainitic steel belonged to the Fe-Cu-Nb series was hot rolled and aged, the influence of aging temperatures on the microstructure and mechanical properties of the steel were investigated by using Scanning electron microscopy (SEM) and transmission electron microscopy(TEM). The results show that the microstructure of the low carbon bainitic steel consisted of lath-shaped bainite(LB), granular bainite(GB) and quasi-polygonal ferrite(QF), and the proportion of each kind of microstructure changed with the aging temperatures. The strength of steel with the increase of aging temperature first increased, then decreased, Aging temperatures had distinct effect on yield strength of the tested steel, and less effect on the ultimate tensile strength, we can get the best comprehensive properties yield strength 1011.87 MPa and elongation rate 16.38% of good tough match aged at 450°C. Through analysis it is concluded that the strength of the tested steels aged at 450°C reaches the maximum value, which is attributed to the precipitation of a large amount of fine ε-Cu particles(5~10nm) and a small number of(Nb,Ti)(C,N) precipitates.

APA, Harvard, Vancouver, ISO, and other styles

15

Hajizad, Omid, Ankit Kumar, Zili Li, Roumen H. Petrov, Jilt Sietsma, and Rolf Dollevoet. "Influence of Microstructure on Mechanical Properties of Bainitic Steels in Railway Applications." Metals 9, no. 7 (July 11, 2019): 778. http://dx.doi.org/10.3390/met9070778.

Full text

Abstract:

Wheel–rail contact creates high stresses in both rails and wheels, which can lead to different damage, such as plastic deformation, wear and rolling contact fatigue (RCF). It is important to use high-quality steels that are resistant to these damages. Mechanical properties and failure of steels are determined by various microstructural features, such as grain size, phase fraction, as well as spatial distribution and morphology of these phases in the microstructure. To quantify the mechanical behavior of bainitic rail steels, uniaxial tensile experiments and hardness measurements were performed. In order to characterize the influence of microstructure on the mechanical behavior, various microscopy techniques, such as light optical microscopy (LOM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), were used. Three bainitic grades industrially known as B360, B1400 plus and Cr-Bainitic together with commonly used R350HT pearlitic grade were studied. Influence of isothermal bainitic heat treatment on the microstructure and mechanical properties of the bainitic grades was investigated and compared with B360, B1400 plus, Cr-Bainitic and R350HT in as-received (AR) condition from the industry. The results show that the carbide-free bainitic steel (B360) after an isothermal heat treatment offers the best mechanical performance among these steels due to a very fine, carbide-free bainitic microstructure consisting of bainitic ferrite and retained austenite laths.

APA, Harvard, Vancouver, ISO, and other styles

16

Koczurkiewicz, Bartosz. "The Effect of Time and Temperature Variations during Isothermal Annealing on the Mechanical Properties of High Carbon Bainitic Steel." Materials Science Forum 706-709 (January 2012): 2158–63. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2158.

Full text

Abstract:

The industrial development require new materials characterized highest mechanical properties. The conditions of thermo-mechanical treatment proved to highest level of mechanical properties for steels. Another method of making strong materials is to reduce the scale of the microstructure using heat treatment [1]. The paper presents the results of investigation into the effect of time and temperature variations during isothermal annealing on the mechanical properties of high carbon (c.a. 0,8%C) bainitic steel. Chemical composition of that steel (addition Si, Mn, Mo and Cr) obtain high level of tensile strength and good plastic properties. The analyzing of published results of researches of high carbon bainitic steels shown, that transformation of bainite can take between 2 to 60 days within the temperature range 125÷325°C [2,3] Based on results of researches of investigated steel a isothermal annealing in temperature range 200÷300°C were done. The experiments were done for 24, 50 and 100 hours of annealing. After that the mechanical tests were done. A Zwick Z100 testing machine was used for tests. The force and elongation values were recorded. On their basis, the proof stress and tensile strength of the steel tested were determined as a function of annealing temperature. The microstructure were determinated too.

APA, Harvard, Vancouver, ISO, and other styles

17

Meng, Jiang Ying, Zhi Geng Jia, Tong Liang Wang, Kai Fang Li, and Li He Qian. "Microstructure and Mechanical Properties of a Lamellar-Structured Low-Alloy TRIP Steel." Materials Science Forum 1016 (January 2021): 1188–92. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.1188.

Full text

Abstract:

In this paper, we report a lamellar-structured low-alloy transformation-induced plasticity (TRIP) steel; the microstructure of the steel consists of alternate lamellae of intercritical ferrite and reverted austenite on microscale, with the latter consisting of bainitic ferrite laths and retained austenite films on nanoscale. Such a microstructure was produced by a heat treatment process similar to that for producing conventional TRIP-assisted steels, i.e. intercritical annealing followed by austempering. Nevertheless, quenched martensite rather than a mixture of ferrite and pearlite was used as the starting structure for intercritical annealing to form austenite, and the resulting austenite was then transformed to bainite by austempering treatment. This steel exhibits much enhanced strength-ductility combinations as compared with those conventional polygonal-structured low-alloy TRIP steels.

APA, Harvard, Vancouver, ISO, and other styles

18

Morri, A., L. Ceschini, M. Pellizzari, C. Menapace, F. Vettore, and E. Veneri. "Effect of the Austempering Process on the Microstructure and Mechanical Properties of 27MnCrB5-2 Steel." Archives of Metallurgy and Materials 62, no. 2 (June 1, 2017): 643–51. http://dx.doi.org/10.1515/amm-2017-0094.

Full text

Abstract:

AbstractThe effect of austempering parameters on the microstructure and mechanical properties of 27MnCrB5-2 steel has been investigated by means of: dilatometric, microstructural and fractographic analyses; tensile and Charpy V-notch (CVN) impact tests at room temperature and a low temperature.Microstructural analyses showed that upper bainite developed at a higher austempering temperature, while a mixed bainitic-martensitic microstructure formed at lower temperatures, with a different amount of bainite and martensite and a different size of bainite sheaf depending on the temperature. Tensile tests highlighted superior yield and tensile strengths (≈30%) for the mixed microstructure, with respect to both fully bainitic and Q&T microstructures, with only a low reduction in elongation to failure (≈10%). Impact tests confirmed that mixed microstructures have higher impact properties, at both room temperature and a low temperature.

APA, Harvard, Vancouver, ISO, and other styles

19

Feng, Chun, Bing Zhe Bai, Y. K. Zheng, and Hong Sheng Fang. "Mn-Series Low Carbon Air Cooling Bainitic Steels Containg Niobium." Advanced Materials Research 89-91 (January 2010): 112–17. http://dx.doi.org/10.4028/www.scientific.net/amr.89-91.112.

Full text

Abstract:

The effect of four different niobium(From 0-0.1%) addition on the mechanical properties of allotriomorphic ferrite (FGBA)/ granular bainite (BG) air cooling bainitic steels has been investigated in this paper. The results show that (1) The 0.06%Nb steel acquired superior strength and toughness combination by applying 1250°C×60min solution treated, finish rolling at 850°C, and air cooling. The corresponding mechanical properties of the thick plate(30mm) is: σb>1050MPa, σ0.2>700MPa,δ5>17%,Akv>90J. (2) The addition of niobium refine the grain size of FGBA, and promoted the transformation of bainite structure. With the increase of niobium content, the refinement of ferrite grain and bainitic cluster is improved. (3) More refined M-A island is acquired by the small addition of niobium. According to M-A Analysis tools and transversal methods, with the rise of niobium content, the volume fraction of M-A island increase from 21% to 35%, and the average size of M-A island decrease from 1.1μm to 0.7um. (4)It is suggested that 0.02-0.06% niobium can improve the mechanical properties of the steel obviously. However, excess addition of Nb (0.1%) deteriorates the impact toughness obviously. (5)Under the synthetic roles of the microstructure refinement and precipitation strengthen, 60-160MPa yield strength improvement has been acquired in the low carbon air cooling bainitic steel by the small addition of niobium. (6)This steel is with low production cost since the alloying element Mn is cheap.

APA, Harvard, Vancouver, ISO, and other styles

20

Domovcová, Lucia, Pavol Beraxa, Milan Mojžiš, Michal Weiss, Martin Fujda, and Ľudovít Parilák. "Microstructure and Mechanical Properties of Steel Grade 14MoV6-3." Materials Science Forum 782 (April 2014): 137–40. http://dx.doi.org/10.4028/www.scientific.net/msf.782.137.

Full text

Abstract:

Steel grade 14MoV6-3 is a low-carbon microalloyed steel with addition of chromium and molybdenum. This medium-strength steel exhibits a ferritic-bainitic microstructure after the heat treatment. This grade is designed mainly for power industry applications, withstanding operating temperatures up to 580 °C; in Železiarne Podbrezová, this particular grade is used for production of hot rolled seamless boiler tubes. In this paper we present the basic chemical concept of 14MoV6-3 steel along with its mechanical properties after the heat treatment. Further, analysis of the final microstructure, carbide phases and precipitation of vanadium is being presented as well. For this purpose, the yield stress theory has been proposed along with predictive nomograms for selected ferritic-bainitic phases. According to the results of DTA analyses, necessary conditions for heat treatment after rolling have been proposed. Finally, CCT diagrams for required ferritic-bainitic structure are presented as well.

APA, Harvard, Vancouver, ISO, and other styles

21

Golański, Grzegorz. "Mechanical Properties of G17CrMoV5 – 10 Cast Steel after Regenerative Heat Treatment." Solid State Phenomena 147-149 (January 2009): 732–37. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.732.

Full text

Abstract:

The paper presents results of research on the influence of regenerative heat treatment on structure and properties of G17CrMoV5 – 10 cast steel. Investigated material was taken out from a turbine frame serviced for over 250 000 hours (total service time) at the temperature of 535 oC. The cast steel after service revealed degraded bainitic-ferritic structure and was characterized by mechanical properties ranging below norm requirements. It has been proved that high tempering temperature in the case of cast steel with bainitic structure ensures optimum combination of mechanical properties and impact energy. It has also been shown that ferrite has a negative influence on impact energy of the cast steel with bainitic-ferritic structure.

APA, Harvard, Vancouver, ISO, and other styles

22

Gao, Yi, Zhong Ping He, Yan Lin He, Lin Li, Ren Yuand Fu, and Lei Zhou. "Effect of Heat Treatment on Microstructure and Mechanical Properties of TRIP Steel Sheets Containing Aluminium." Advanced Materials Research 391-392 (December 2011): 554–58. http://dx.doi.org/10.4028/www.scientific.net/amr.391-392.554.

Full text

Abstract:

Effect of heat treatment on microstructure of TRIP steel sheets containing aluminium was investigated on Gleeble 3500 thermal simulation testing machine. The microstructure evolution with variation of time and temperature was measured by means of optical metallography (OM) and X-ray stress analyzer. The tensile properties of TRIP steel at room temperature were also measured. It was shown that the maxium value of product of strength and ductility of 22858 MPa% was obtained by treatment of intercritical annealing temperature at 800 for 3 mins and bainitic holding temperature at 400 for 6 mins. The value of yield strength was mainly determinated by the volume fraction of bainite and the content of retained austenite was the key factor to result in optimum strength and ductility of TRIP steel. In addition, the properties of TRIP steel were markedly decreased because martensite, which was deleterious to the ductility, was present in microstructure of the steel soaking at bainitic temperature 350。C for 6 mins.

APA, Harvard, Vancouver, ISO, and other styles

23

Feng, Chun, Bing Zhe Bai, Y. K. Zheng, and Hong Sheng Fang. "Mn-Series Low Carbon Air Cooling Bainitic Steels Containing Niobium." Materials Science Forum 638-642 (January 2010): 3038–43. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.3038.

Full text

Abstract:

The effect of four different niobium(From 0-0.1%) addition on the mechanical properties of allotriomorphic ferrite (FGBA)/ granular bainite (BG) air cooling bainitic steels has been investigated in this paper. The results show that (1) The 0.06%Nb steel acquired superior strength and toughness combination by applying 1250°C×60min solution treated, finish rolling at 850°C, and air cooling. The corresponding mechanical property of the thick plate (30mm) is: σb>1050MPa, σ0.2>700MPa, δ5>17%, Akv>90J. (2) The addition of niobium refine the grain size of FGBA, and promoted the transformation of bainite structure. With the increase of niobium content, the refinement of ferrite grain and bainitic cluster is improved. (3) More refined M-A island is acquired by the small addition of niobium. According to M-A Analysis tools and transversal methods, with the rise of niobium content, the volume fraction of M-A island increase from 21% to 35%, and the average size of M-A island decrease from 1.1μm to 0.7um. (4) It is suggested that 0.02-0.06% niobium can improve the mechanical properties of the steel obviously. However, excess addition of Nb (0.1%) deteriorates the impact toughness obviously. (5) Under the synthetic roles of the microstructure refinement and precipitation strengthen, 60-160MPa yield strength improvement has been acquired in the low carbon air cooling bainitic steel by the small addition of niobium. (6) This steel is with low production cost since the alloying element Mn is cheap.

APA, Harvard, Vancouver, ISO, and other styles

24

Radović, Nenad, Ankica Koprivica, Dragomir Glišić, Abdunnaser Fadel, and Djordje Drobnjak. "Influence of V and N on Transformation Behavior and Mechanical Properties of Medium Carbon Forging Steels." Materials Science Forum 638-642 (January 2010): 3459–64. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.3459.

Full text

Abstract:

The influence of vanadium and nitrogen on microstructure and mechanical properties of medium-carbon steels has been studied by means of metallography and mechanical testing. Vanadium addition to the low nitrogen steel suppresses the formation of ferrite-pearlite following the low reheating temperatures and microstructure consists of bainitic sheaves. Increasing nitrogen at the same vanadium level promotes the acicular ferrite formation. For high reheating temperatures, dominantly acicular ferrite structure in both the low nitrogen and the high nitrogen vanadium steels is obtained. The results suggest that vanadium in solid solution promotes the formation of bainite, whereas the effect of nitrogen is related to the precipitation of VN particles in austenite with high potency for intragranular nucleation of acicular ferrite and to the precipitation of V(C,N) particles in ferrite with high potency for precipitation strengthening. Addition of both vanadium and nitrogen considerably increases the strength level, while CVN20 impact energy increases on changing the microstructure from bainitic ferrite to the fine ferrite-pearlite and acicular ferrite.

APA, Harvard, Vancouver, ISO, and other styles

25

Sugimoto, Koh-ichi. "Performance of Mechanical Properties of Ultrahigh-Strength Ferrous Steels Related to Strain-Induced Transformation." Metals 10, no. 7 (July 1, 2020): 875. http://dx.doi.org/10.3390/met10070875.

Full text

Abstract:

Ultrahigh-strength ferrous steels, related to the strain-induced martensite transformation (or transformation-induced plasticity: TRIP) of metastable retained austenite, such as TRIP-aided bainite/martensite steels, quenching and partitioning steels, nanostructured bainitic steels (or carbide free bainitic steels) and medium manganese steels, are currently receiving a great deal of attention from both academic and industry sectors, due to their excellent formability and mechanical properties [...]

APA, Harvard, Vancouver, ISO, and other styles

26

Caballero, Rementeria, Morales-Rivas, Benito-Alfonso, Yang, de Castro, Poplawsky, Sourmail, and Garcia-Mateo. "Understanding Mechanical Properties of Nano-Grained Bainitic Steels from Multiscale Structural Analysis." Metals 9, no. 4 (April 9, 2019): 426. http://dx.doi.org/10.3390/met9040426.

Full text

Abstract:

Steel components working in extreme conditions require materials presenting the highest performances. Nowadays, nanoengineering is being applied to the development of ultra-high strength steels as a key-enabling technology in the steel sector. The present article describes the multiscale structure of nano-grained steels designed using atomic transformation theory and processed by a simple heat treatment. Outstanding mechanical properties for these novel steels are reported, and strain-hardening mechanisms are discussed.

APA, Harvard, Vancouver, ISO, and other styles

27

Abd El Rahman, Sherif Ali, Ahmed Shash, Mohamed K. El-Fawkhry, Ahmed Zaki Farahat, and Taha Mattar. "Designing, Processing and Isothermal Transformation of Al-Si Medium Carbon Ultrafine High Strength Bainitic Steel." Defect and Diffusion Forum 380 (November 2017): 1–11. http://dx.doi.org/10.4028/www.scientific.net/ddf.380.1.

Full text

Abstract:

Medium-carbon, silicon-rich steels are commonly suggested to obtain a very fine bainitic microstructure at a low temperature slightly above Ms. Thereby, the resulted microstructure consists of slender bainitic-ferritic plates interwoven with retained austenite. The advanced strength and ductility package of this steel is much dependent on the fineness of bainitic ferrite, as well as the retained austenite phase. In this article, the aluminum to silicon ratio, and the isothermal transformation temperature have been adopted to obtain ultra-high strength high carbon steel. Optical and SEM investigation of the produced steels have been performed. XRD has been used to track the retained austenite development as a result of the change in the chemical composition of developed steels and heat treatment process. Mechanical properties in terms of hardness and microhardness of obtained phases and structure were investigated. Results show that the increment of aluminum to silicon ratio has a great effect in promoting the bainitic transformation, in tandem with improving the stability and the fineness of retained austenite. Such an advanced structure leads to enhancement in the whole mechanical properties of the high carbon steel.

APA, Harvard, Vancouver, ISO, and other styles

28

Shen, Hai Ming, Zhuo Zhang, and Yong You Tian. "Manufacture and Research on Performance and Organizations of New Type Carburized Bainitic Hollow Steel." Advanced Materials Research 391-392 (December 2011): 246–49. http://dx.doi.org/10.4028/www.scientific.net/amr.391-392.246.

Full text

Abstract:

A manufacturing process of new type carburized bainitic hollow steel by “hot-penetrating and hot-rolling” method is described in this paper. A good surface quality and hot working performance can be achieved by using hot-penetrating and hot-rolling method fabricated new type bainitic hollow steel. The mechanical properties ofnew type carburized bainitic hollow steel can satisfy the properties of Cr-Ni type carbonized steel requirements, so the hollow steel can be used as drill steel material. The carburized test of new type bainitic hollow steel showed that the new steel is organized by the bainitic, ferrite and austenite; the layer of cementite is organized by the high carbon martensite and austenite. The drill rod with the new type carburized bainitic hollow steel is with good carburization properties. After carburizing air (wind) cold, the surface hardness of the dill rod will satisfy HRC> 5~7, with good air cooling harden ability and harden ability, so the new type carburized bainitic hollow steelis good at practical application.

APA, Harvard, Vancouver, ISO, and other styles

29

Xie, Hui, Lin Xiu Du, and Jun Hu. "Effect of Cooling Procedure on Tensile and Charpy Impact Properties of Cr-Mo Ultra-High Strength Steel." Materials Science Forum 816 (April 2015): 761–68. http://dx.doi.org/10.4028/www.scientific.net/msf.816.761.

Full text

Abstract:

The effect of cooling procedure on the transformation behavior of low-carbon Cr-Mo microalloyed steel was investigated by using microstructural observations, mechanical properties and impact fractographs. Three steel plates were adopted under three different cooling rates, and their microstructure, tensile and impact properties were evaluated. The results indicated that the strength of experimental steels was increased and the impact toughness was decreased with decreasing the coiling temperature. Steel A consisted of granular bainite, coarse bainitic ferrite lath and M/A constituent subjected to a coiling temperature of 560 oC. The yield strength, tensile strength and impact energy of 1/2-size Charpy impact at-20 oC were 740MPa, 1020MPa, and 33.5J, respectively, which were imperfect in strength. The effects of coiling temperature were potent on the refinement of microstructure and the size of M/A constituents. Steel B consisted of a small amount of lath bainite, fine M/A constituents and bainitic ferrite lath subjected to a lower coiling temperature of 520 oC. The yield strength, tensile strength and impact energy of 1/2-size Charpy impact at-20°C were 840MPa, 1030MPa, and 30.7J, respectively. However, steel C was composed of lath bainite and lath martensite subjected to the lowest coiling temperature of 380 oC (slightly above Ms point). The yield strength, tensile strength and impact energy of 1/2-size Charpy impact at-20 oC were 985MPa, 1200MPa and 22.5J, respectively, which could meet the demand of ultra high strength structural steel applications.

APA, Harvard, Vancouver, ISO, and other styles

30

Kliber, Jiří, Gabriela Plestilova, Ondrej Zacek, and Mahesh C. Somani. "Effects of Thermomechanical Processing on Microstructure and Mechanical Properties Multiphase Steels Exhibiting a TRIP Effect." Materials Science Forum 539-543 (March 2007): 4357–62. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4357.

Full text

Abstract:

Effects of hot-rolling conditions on these steels are much less studied than their importance for practice would suggest. It should be emphasized that bainite transformation is the key reaction to enrich non-transformed austenite with carbon. This study was carried out in order to gain understanding of the effect of thermomechanical hot rolling on final microstructure and mechanical properties of C-Mn-Si TRIP steel. Fundamental of the transformation induced plasticity effect – TRIP is the stabilization of substantial amount of retained austenite down to the ambient temperature by thermomechanical processing and its subsequent transformation into strain induced martensite as a consequence of applied plastic deformation. The special prepared stepped specimens were rolled on laboratory tandem mill. The effects of finish rolling temperature, strain and isothermal bainite transformation temperature on mechanical properties of mentioned TRIP steel were evaluated (mechanical properties were examined with tension test). Major deformation, higher finishing rolling temperature and higher temperature of bainite hold result in drop in strength. Proportionately to the drop in strength, the ductility grows in the TRIP steel. Microstructures were examined with X-ray diffraction (retained austenite). Image analysis software was used to process SEM micrographs of structure (ferrite, bainite assessment). Plastometric testing was conducted on GLEEBLE 3800 thermo-mechanical simulator. First stage of experiment yielded stress-strain curves for various temperatures and strain rates. Gleeble 1500 was used for the remaining plastometric simulation. Specimens were reheated to austenitization temperature of 1100°C and soaked. Then they were cooled to the temperature of deformation and subsequently cooled at higher rate down to the bainitic transformation temperature (400 – 550 °C). Specimens were held at the bainitic transformation temperature and then air-cooled. Final microstructures were evaluated with respect to transformation diagrams and optical microscopy findings. Higher bainite volume fraction was found in the specimens cooled at higher cooling rate as compared with more slowly cooled specimens.

APA, Harvard, Vancouver, ISO, and other styles

31

Zhang, Qi, Li Li, Wei Ding, Hong Tu Song, and Zhen Kun Gao. "Investigation on Process and Welded Joint Mechanical Properties of Bainitic Steel Rail Flash Butt Welding." Key Engineering Materials 723 (December 2016): 406–11. http://dx.doi.org/10.4028/www.scientific.net/kem.723.406.

Full text

Abstract:

Combine with the characteristics of bainitic rail U20Mn2SiCrNiMo, the flash butt welding process that suitable bainitic rail is optimized for improving bainitic joints’ performance basing on the mature technology of pearlitic rail flash butt welding, through approaches of lower heat input appropriate and matched upset forging length parameters, et.. In the post welding treatment, controlling the heating process strictly and using slow cooling measures are done to further optimize the properties of the welded joints. Then the performance tests are done on the bainitic rail joints welded with optimized welding and post welding process. The study results approve that the qualified bainitic rail joints can be obtained through appropriate flash butt welding process. Tensile strength and impact energy of bainitic joints are superior to pearlitic rail joints, but the elongation is reverse. The impact fracture of bainitic rail flash welded joints appear more defects such as hot cracks and silicate inclusions than pearlitic joints. Compared with parent metal, both types of the rail joints appear higher strength, but lower elongation and impact energy. The decreased percentage of bainitic rail joints compared with their parents is larger than pearlitic joints.

APA, Harvard, Vancouver, ISO, and other styles

32

Chatterjee, Subrata, S. K. Ghosh, and P. S. Bandyopadhyay. "Thermo-Mechanically Controlled Processed Ultrahigh Strength Steels." Materials Science Forum 783-786 (May 2014): 685–91. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.685.

Full text

Abstract:

A low-carbon, titanium and niobium (Ti-Nb) bearing and a low-carbon titanium, niobium and copper (Ti-Nb-Cu) bearing ultra high strength steel have been thermo-mechanically processed on a laboratory scale unit. Evolution of microstructure and mechanical properties of the above air cooled steels have been studied at different finish rolling temperatures (FRTs). Microstructural characterization reveals largely a mixture of granular bainite and bainitic ferrite along with the precipitation of microalloying carbide/carbonitride particles and/or Cu-rich precipitates. (Ti-Nb) bearing steel yields higher yield strength (1114-1143 MPa) along with higher tensile strength (1591-1688 MPa) and moderate ductility (12-13%) as compared to (Ti-Nb-Cu) bearing steel having yield strength (934-996 MPa) combined with tensile strength (1434-1464 MPa) and similar ductility (13%) for the selected range of 850-750°C FRT. Due to higher strength-ductility combinations, these present investigated steels can be regarded as the replacement material for ballistic applications as well as other sectors like defense, pipeline, cars, pressure vessels, ships, offshore platforms, aircraft undercarriages and rocket motor casings etc. Key words: Thermo-mechanical controlled processing, ultra high strength steel, microstructure, mechanical properties.

APA, Harvard, Vancouver, ISO, and other styles

33

Wang, Y. H., F. C. Zhang, and T. S. Wang. "A novel bainitic steel comparable to maraging steel in mechanical properties." Scripta Materialia 68, no. 9 (May 2013): 763–66. http://dx.doi.org/10.1016/j.scriptamat.2012.12.031.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Sugimoto, Koh-ichi, Sho-hei Sato, Junya Kobayashi, and Ashok Kumar Srivastava. "Effects of Cr and Mo on Mechanical Properties of Hot-Forged Medium Carbon TRIP-Aided Bainitic Ferrite Steels." Metals 9, no. 10 (September 30, 2019): 1066. http://dx.doi.org/10.3390/met9101066.

Full text

Abstract:

In this study, the effects of Cr and Mo additions on mechanical properties of hot-forged medium carbon TRIP-aided bainitic ferrite (TBF) steel were investigated. If 0.5%Cr was added to the base steel with a chemical composition of 0.4%C, 1.5%Si, 1.5%Mn, 0.5%Al, and 0.05%Nb in mass%, the developed steel achieved the best combination of strength and total elongation. The best combination of strength and impact toughness was attained by multiple additions of 0.5%Cr and 0.2%Mo to the base steel. The excellent combination of strength and impact toughness substantially exceeded those of quenched and tempered JIS-SCM420 and 440 steels, although it was as high as those of 0.2%C TBF steels with 1.0%Cr and 0.2%Mo. The good impact toughness was mainly caused by uniform fine bainitic ferrite matrix structure and a large amount of metastable retained austenite.

APA, Harvard, Vancouver, ISO, and other styles

35

Meng, Jiang Ying, Lei Jie Zhao, Fan Huang, Fu Cheng Zhang, and Li He Qian. "Isothermal Transformation, Microstructure and Mechanical Properties of Ausformed Low-Carbon Carbide-Free Bainitic Steel." Materials Science Forum 941 (December 2018): 329–33. http://dx.doi.org/10.4028/www.scientific.net/msf.941.329.

Full text

Abstract:

In the present study, the effects of ausforming on the bainitic transformation, microstructure and mechanical properties of a low-carbon rich-silicon carbide-free bainitic steel have been investigated. Results show that prior ausforming shortens both the incubation period and finishing time of bainitic transformation during isothermal treatment at a temperature slightly above the Mspoint. The thicknesses of bainitic ferrite laths are reduced appreciably by ausforming; however, ausforming increases the amount of large blocks of retained austenite/martenisite and decreases the volume fraction of retained austenite. And accordingly, ausforming gives rise to significant increases in both yield and tensile strengths, but causes noticeable decreases in ductility and impact toughness.

APA, Harvard, Vancouver, ISO, and other styles

36

Liang, Xiao Jun, Ming Jian Hua, and Anthony J. DeArdo. "The Influence of Thermomechanical Controlled Processing on Bainite Formation in Low Carbon High Strength Steel." Materials Science Forum 783-786 (May 2014): 21–26. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.21.

Full text

Abstract:

Thermomechanical controlled processing is a very important way to control the microstructure and mechanical properties in low carbon, high strength steel. This is especially true in the case of bainite formation, where the complexity of the austenite-bainite transformation makes the control of the processing important. In this study, a low carbon, high manganese steel containing niobium was investigated to better understand the roles of austenite conditioning and cooling rates on the bainitic phase transformation. Specimens were compared with and without deformation, and followed by seven different cooling rates ranging between 0.5°C/s and 40°C/s. The CCT curves showed that the transformation behaviors and temperatures are very different. The different bainitic microstructures which varied with austenite deformation and cooling rates will be discussed.

APA, Harvard, Vancouver, ISO, and other styles

37

Oktay, Serkan, Paolo Emilio Di Nunzio, and Mustafa Kelami Şeşen. "Investigation of the effect of isothermal heat treatments on mechanical properties of thermo-mechanically rolled S700MC steel grade." Acta Metallurgica Slovaca 26, no. 1 (March 18, 2020): 11–16. http://dx.doi.org/10.36547/ams.26.1.449.

Full text

Abstract:

The effect of isothermal heat treatments (1 hour at 200, 400, 600 and 800°C) on mechanical properties of thermo-mechanically rolled S700MC steel has been investigated by extensive mechanical characterizations. Treatments at 600°C increase yield and tensile strength and decrease impact energy. Below 600°C the steel retains its bainitic structure. Precipitation kinetics simulations indicate that this secondary hardening effect arises from the nucleation of fine (Nb,Ti)C particles, indicating that the bainitic structure is unstable above 600°C due to its high supersaturation with respect to C, Nb and Ti. These results can help to optimize the operating practices for post-weld heat treatments.

APA, Harvard, Vancouver, ISO, and other styles

38

Oja, Olli, Ari Saastamoinen, Madan Patnamsetty, Mari Honkanen, Pasi Peura, and Martti Järvenpää. "Microstructure and Mechanical Properties of Nb and V Microalloyed TRIP-Assisted Steels." Metals 9, no. 8 (August 14, 2019): 887. http://dx.doi.org/10.3390/met9080887.

Full text

Abstract:

The intercritical annealing and isothermal bainitic processing response was studied for three Nb and V microalloyed Transformation-Induced Plasticity (TRIP)-assisted 980 MPa grade steels. Their mechanical and microstructural properties were compared to industrially produced TRIP 800 steel. Depending on the isothermal holding temperature and microalloying, the experimental steels reached properties comparable to the reference steel. The retained austenite content did not show direct correlation to elongation properties. Niobium was found to be more effective microalloying element than vanadium in increasing the elongation properties, which were investigated by measuring true fracture strain from tensile test specimens.

APA, Harvard, Vancouver, ISO, and other styles

39

Yin, Yun Yang, Fang Fang, and Zhi Jin Fan. "Microstructure and Mechanical Properties of Hot Rolled TRIP Steel Based on Dynamic Transformation of Undercooled Austenite." Advanced Materials Research 152-153 (October 2010): 1038–43. http://dx.doi.org/10.4028/www.scientific.net/amr.152-153.1038.

Full text

Abstract:

The microstructure characteristics and tensile properties in a 0.2C-1.5Mn-1.0Al-0.50Si, high strength hot rolled TRIP steel obtained by a new processing based on dynamic transformation of undercooled austenite(DTUA) were investigated. The results show that the main feature of the new technology is that the ferrite was produced by the applied strain during DTUA. Characterization by means of optical and scanning electron microscopy, transmission electron microscopy and X-ray diffraction has shown that the microstructure of the investigated steel contained a ferrite matrix with fine grain size, bainite with small bainitic packets, and high volume fraction of retained austenite with a large number of granular retained austenite. Tensile testing indicates the steels produced by this processing have higher strength (790MPa) and total elongation (35%) as well as low yield ratio..

APA, Harvard, Vancouver, ISO, and other styles

40

Chen, Xi, Fuming Wang, Changrong Li, and Jing Zhang. "Dynamic continuous cooling transformation, microstructure and mechanical properties of medium-carbon carbide-free bainitic steel." High Temperature Materials and Processes 39, no. 1 (July 18, 2020): 304–16. http://dx.doi.org/10.1515/htmp-2020-0051.

Full text

Abstract:

AbstractThe effects of the cooling rate after hot deformation on phase transformation, the microstructure of the designed nonquenched and tempered medium-carbon carbide-free bainitic steel have been investigated during the dynamic continuous cooling process. The results show that with the increase of the cooling rate, the morphology of the carbide-free bainite of the experimental steel evolves from granular bainite to lath bainite. Meanwhile, the hardness increases, and the amount of the retained austenite decreases with the increase of the cooling rate. Besides, the morphology evolution of the retained austenite from block to film is revealed by EBSD. Moreover, 0.5°C/s is considered to be the favorable cooling rate to obtain the best strength–toughness matching. Furthermore, the semi-industrial experimental results proved that the tensile strength, yield strength and Charpy impact energy were 1,298 MPa, 847 MPa and 38 J, respectively.

APA, Harvard, Vancouver, ISO, and other styles

41

Ali, Mohammed, Tun Nyo, Antti Kaijalainen, Jaakko Hannula, David Porter, and Jukka Kömi. "Influence of Chromium Content on the Microstructure and Mechanical Properties of Thermomechanically Hot-Rolled Low-Carbon Bainitic Steels Containing Niobium." Applied Sciences 10, no. 1 (January 2, 2020): 344. http://dx.doi.org/10.3390/app10010344.

Full text

Abstract:

The effect of chromium content in the range of 1 wt.%–4 wt.% on the microstructure and mechanical properties of controlled-rolled and direct-quenched 12 mm thick low-carbon (0.04 wt.%) steel plates containing 0.06 wt.% Nb has been studied. In these microalloyed 700 MPa grade steels, the aim was to achieve a robust bainitic microstructure with a yield strength of 700 MPa combined with good tensile ductility and impact toughness. Continuous cooling transformation diagrams of deformed and non-deformed austenite were recorded to study the effect of Cr and hot deformation on the transformation behavior of the investigated steels. Depending on the cooling rate, the microstructures consist of one or more of the following microstructural constituents: bainitic ferrite, granular bainite, polygonal ferrite, and pearlite. The fraction of bainitic ferrite decreases with decreasing cooling rate, giving an increasing fraction of granular bainite and polygonal ferrite and a reduction in the hardness of the transformation products. Polygonal ferrite formation depends mainly on the Cr content and the cooling rate. In both deformed and non-deformed austenite, increasing the Cr content enhances the hardenability and refines the final microstructure, shifting the ferrite start curve to lower cooling rates. Preceding austenite deformation promotes the formation of polygonal ferrite at lower cooling rates, which leads to a decrease in hardness. In hot-rolled and direct-quenched plates, decreasing the Cr content promotes the formation of polygonal ferrite leading to an increase in the impact toughness and elongation but also a loss of yield strength.

APA, Harvard, Vancouver, ISO, and other styles

42

Zhang, Tao, Hua Xing Hou, and Jun Ping Chen. "The Influence of Ti/N Ratio on the Effective Boron and Mechanical Properties of Low Carbon Boron Alloyed Bainitic Steel." Applied Mechanics and Materials 496-500 (January 2014): 392–95. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.392.

Full text

Abstract:

The influence of Ti/N ratio on the effective boron and mechanical properties was investigated by analyzing data from low carbon boron alloyed bainitic steel plates. The result shows Ti/N ratio varies with effective boron value. Less than 50% effective boron was obtained when Ti/N ratio is below 3.3, nearly 90% effective boron is obtained when ratio Ti/N is more than 4; Adding enough Titanium is an effective and economic way to improve qualified ratio of bainitic steel plate. The Ti content between 0.010% and 0.030% does not have obvious effect on the toughness of the bainitic steel;

APA, Harvard, Vancouver, ISO, and other styles

43

Eggbauer, Gernot, and Bruno Buchmayr. "Optimized Cooling Strategies for Bainitic Forging Steels." Key Engineering Materials 716 (October 2016): 472–80. http://dx.doi.org/10.4028/www.scientific.net/kem.716.472.

Full text

Abstract:

New steel grades for forged components are designed to meet the requirements of the automotive industry in order to obtain excellent strength and toughness behavior as well as a high endurance limit. Beside precipitation hardened ferritic-pearlitic steels, bainitic steels have gained more and more importance. Basic considerations on the alloy design (C-, Si-, Cr-; B-content) are done using JMatPro-Calculations and by some experimental trials. Using the thermomechanical testing system Gleeble 3800, various cooling strategies have been applied and the kinetics of the bainite formation has been measured at different holding temperatures and times. A detailed microstructural characterization has been done with relation to the mechanical properties. The isothermal tests are compared to continuous cooling situations. Finally, forging trials are performed to find out the most suitable and robust production schedule to be used in practice. The actual findings support the increasing use of bainitic steels for forged parts, especially regarding material saving, independence of cross section and good fatigue performance.

APA, Harvard, Vancouver, ISO, and other styles

44

Wang, Hongcai, Lijie Cao, Yujiao Li, Mike Schneider, Eric Detemple, and Gunther Eggeler. "Effect of cooling rate on the microstructure and mechanical properties of a low-carbon low-alloyed steel." Journal of Materials Science 56, no. 18 (March 12, 2021): 11098–113. http://dx.doi.org/10.1007/s10853-021-05974-3.

Full text

Abstract:

AbstractHeavy plate steels with bainitic microstructures are widely used in industry due to their good combination of strength and toughness. However, obtaining optimal mechanical properties is often challenging due to the complex bainitic microstructures and multiple phase constitutions caused by different cooling rates through the plate thickness. Here, both conventional and advanced microstructural characterization techniques which bridge the meso- and atomic-scales were applied to investigate how microstructure/mechanical property-relationships of a low-carbon low-alloyed steel are affected by phase transformations during continuous cooling. Mechanical tests show that the yield strength increases monotonically when cooling rates increase up to 90 K/s. The present study shows that this is associated with a decrease in the volume fraction of polygonal ferrite (PF) and a refinement of the substructure of degenerated upper bainite (DUB). The fine DUB substructures feature C-rich retained austenite/martensite-austenite (RA/M-A) constitutes which decorate the elongated micrograin boundaries in ferrite. A further increase in strength is observed when needle-shaped cementite precipitates form during water quenching within elongated micrograins. Pure martensite islands on the elongated micrograin boundaries lead to a decreased ductility. The implications for thick section plate processing are discussed based on the findings of the present work.

APA, Harvard, Vancouver, ISO, and other styles

45

Kumar, Avanish, and Aparna Singh. "Mechanical properties of nanostructured bainitic steels." Materialia 15 (March 2021): 101034. http://dx.doi.org/10.1016/j.mtla.2021.101034.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

El-Shenawy, Eman, Hoda Refaiy, and Hoda Nasr El-Din. "Thermal Stability of Retained Austenite in Advanced TRIP Steel with Bainitic Ferrite Matrix for Automotive Industries." Materials Science Forum 1016 (January 2021): 429–34. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.429.

Full text

Abstract:

Multiphase steels consisting of retained austenite and martensite/bainite microstructures such as TRIP, low-temperature-bainite, and Q&P steels are attractive candidates for the new-generation of AHSS. These steels exhibit a remarkable combination of strength and toughness which is essential to meet the objective of weight reduction of engineering-components, while maintaining the compromise of tough-safety requirements. Such good mechanical properties are due to the enhanced work hardening rate caused by austenite-to-martensite transformation during deformation and the strengthening contribution of martensite/bainite. The retained austenite can thermally decompose into more thermodynamically stable phases as a consequence of temperature changes, which is referred to as the thermal stability of retained austenite. TRIP-aided steel is an effective candidate for automotive parts because of safety and weight reduction requirements. The strength–ductility balance of high strength steel sheets can be remarkably improved by using transformation induced plasticity behavior of retained austenite. In manufacturing hot rolled TRIP-aided sheet steels, austenite transforms into bainite during the coiling process. Because black hot coils cool slowly after the coiling process, they are exposed at about 350–450°C for a few hours or days. Therefore, the metastable residual austenite can be decomposed into other phases. This decomposition of residual austenite can produce serious deteriorate of mechanical properties in hot rolled TRIP-aided sheet steels. The present work identified the decomposition behavior and study the thermal stability of retained austenite in the TRIP-aided steel with bainitic/ferrite matrix depending on coiling temperatures and holding times by means of DSC and XRD analysis.

APA, Harvard, Vancouver, ISO, and other styles

47

Zhuang, Wei Min, Wan Dong Yu, and Yan Hong Chen. "Investigation on the Deformation Pattern and Energy Absorption Capacity of Hot-Stamping Structures with Partial Pressing Hardening." Advanced Materials Research 488-489 (March 2012): 87–92. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.87.

Full text

Abstract:

Compared to traditional hot-stamping process, partial pressing hardening (PPH) can alter mechanical properties of metal components in any desired regions by controlling its bainite and martensite distribution. The mechanical property of the structure that is produced by PPH process is quite different from traditional hot-stamping steels (Martensitic steels) and has never been evaluated. Based on the merit of PPH process, this paper investigated the effect of bainite-martensite distribution on the deformation pattern and energy absorption capacity of PPH structures. The FE material models of martensitic and bainitic steel were set up and verified. After that, the deformation pattern and energy absorption capacity of PPH structures with different distribution patterns was investigated and discussed by three-point bending and tensile bending FE simulation.

APA, Harvard, Vancouver, ISO, and other styles

48

Guo, Yanbing, Zhuguo Li, Liqun Li, and Kai Feng. "The Effects of Micro-Segregation on Isothermal Transformed Nano Bainitic Microstructure and Mechanical Properties in Laser Cladded Coatings." Materials 13, no. 13 (July 6, 2020): 3017. http://dx.doi.org/10.3390/ma13133017.

Full text

Abstract:

The design of metastable retained austenite is the key issue to obtain nano bainitic steel with high strength and toughness. In this study, nanostructured Fe-based bainitic coatings were fabricated using laser cladding and following isothermal heat treatment. The microstructures and mechanical properties of the laser cladded coating were investigated. The results show that the Mn, Cr, Co, and Al segregated at the solidified prior grain boundaries. The micro-segregation of the solutes strongly influenced the stability of the austenite. As the isothermal temperature decreases, the interface of the bainite and blocky retained austenite approach to the prior interdendritic regions with the decreasing isothermal temperature, and the final volume fraction also decreases. The volume fractions of each phase and microstructure morphology of the coatings were determined by the interdendritic micro-segregation and isothermal temperatures. The stability of the blocky retained austenite distributed at the interdendritic area was lower than that of film and island-like morphology. This phenomenon contributed to the ductile and tough nano bainitic coatings with tunable mechanical properties.

APA, Harvard, Vancouver, ISO, and other styles

49

Rana, R., S. Chen, A. Haldar, and S. Das. "Mechanical Properties of a Bainitic Steel Producible by Hot Rolling." Archives of Metallurgy and Materials 62, no. 4 (December 1, 2017): 2331–38. http://dx.doi.org/10.1515/amm-2017-0342.

Full text

Abstract:

AbstractA carbide-free bainitic microstructure is suitable for achieving a combination of ultra high strength and high ductility. In this work, a steel containing nominally 0.34C-2Mn-1.5Si-1Cr (wt.%) was produced via industrial hot rolling and laboratory heat treatments. The austenitization (900°C, 30 min.) and austempering (300-400°C, 3 h) treatments were done in salt bath furnaces. The austempering treatments were designed to approximately simulate the coiling step, following hot rolling and run-out-table cooling, when the bainitic transformation would take place and certain amount of austenite would be stabilized due to suppression of carbide precipitation. The microstructures and various mechanical properties (tensile properties, bendability, flangeability, and room and subzero temperature impact toughness) relevant for applications were characterized. It was found that the mechanical properties were highly dependent on the stability of the retained austenite, presence of martensite in the microstructure and the size of the microstructural constituents. The highest amount of retained austenite (~ 27 wt.%) was obtained in the sample austempered at 375°C but due to lower austenite stability and coarser overall microstructure, the sample exhibited lower tensile ductility, bendability, flangeability and impact toughness. The sample austempered at 400°C also showed poor properties due to the presence of initial martensite and coarse microstructure. The best combination of mechanical properties was achieved for the samples austempered at 325-350°C with a lower amount of retained austenite but with the highest mechanical stability.

APA, Harvard, Vancouver, ISO, and other styles

50

Usuki, Hideki, Kunio Namiki, and Tomohito Iikubo. "Effect of microstructure on the mechanical properties of bainitic steel." DENKI-SEIKO[ELECTRIC FURNACE STEEL] 59, no. 1 (1988): 15–26. http://dx.doi.org/10.4262/denkiseiko.59.15.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Bainitic steel – Mechanical properties'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles