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1
Jiang, She Ming, Shi Jie Feng, Zhen Hua Li, and Qi Fu Zhang. "Influence of Oxide Morphologies on the Galvanizability of the Third Generation Automotive Steel." Advanced Materials Research 887-888 (February 2014): 233–39. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.233.
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Focusing on improving the galvanizability of the third generation automotive steel, the effect of surface oxides morphologies on the galvanizability was studied. The results show that the surface oxide types of sample steels by XPS analysis after annealing in different conditions are the same, only MnO and Cr2O3 were detected and no complex oxides exist on the surface. Morphologies of surface oxides can greatly influence the galvanizability of the third generation automotive steel, nodule-like oxides surface can contribute to better wettability and inhibition layer than vitreous film-like oxides surface. Galvanizing panels of nodule-like oxides surface steels only show pinhole-sized bare spots, while panels galvanized from vitreous film-like oxide surface steels reveal larger areas of bare spots and uncoated areas. Inhibition layer observed in galvanizing panels of nodule-like oxides surface steels are compact but not homogeneous, some inhibition layer grains are fine, and others are coarse. While the inhibition layer grains of panels galvanized from vitreous film-like oxide surface steels have a non-compact morphology with some particularly fine equiaxed crystals which developed deficiently.
2
Du, Hongying, Andrey Karasev, Olle Sundqvist, and Pär Jönsson. "Modification of Non-Metallic Inclusions in Stainless Steel by Addition of CaSi." Metals 9, no. 1 (January 12, 2019): 74. http://dx.doi.org/10.3390/met9010074.
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The focus of this study involved comparative investigations of non-metallic inclusions in 316L stainless steel bars without and with Ca treatments. The inclusions were extracted by using electrolytic extraction (EE). After that, the characteristics of the inclusions, such as morphology, size, number, and composition, were investigated by using a scanning electron microscope (SEM) in combination with an energy dispersive X-ray spectroscopy (EDS). The following four types of inclusions were observed in 316L steels: (1) Elongated MnS (Type I), (2) MnS with hard oxide cores (Type II), (3) Undeformed irregular oxides (Type III), and (4) Elongated oxides with a hard oxide core (Type IV). In the reference sample, only a small amount of the Type III oxides (Al2O3–MgO–MnO–TiOx) existed. However, in Ca-treated 316L steel, about 46% of the observed inclusions were oxide inclusions (Types III and IV) correlated to gehlenite and to a mixture of gehlenite and anorthite, which are favorable for the machinability of steel. Furthermore, untransformed oxide cores (Al2O3–MgO–MnO) were also found in the inclusions of Type IV. The mechanism leading to different morphologies of oxide inclusions is also discussed.
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Maderthaner, Magdalena, Alexander Jarosik, Gerhard Angeli, and Roland Haubner. "Effect of Dew Point on the Selective Oxidation of Advanced High Strength Steels." Materials Science Forum 891 (March 2017): 292–97. http://dx.doi.org/10.4028/www.scientific.net/msf.891.292.
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The effect of the dew point (and therefore oxygen partial pressure) on the selective oxidation of Advanced High Strength Steels was investigated. Steels with different Si contents, 0.2 wt% Si, 0.8 wt% Si and 1.5 wt% Si were used. The steel samples were annealed at 840 °C for 60 s and various gas atmospheres prior to hot-dip galvanized at 460 °C. The dew point of the 5 % H2-N2 annealing atmosphere was lowered from-30 °C (equivalent to 380 ppm H2O) to-58 °C (equivalent to 14 ppm H2O) in order to investigate surface segregation of alloying elements Si, Mn and Cr. These conditions are reducing for Fe, but oxidizing the oxygen-affine elements. Oxide morphology changed from a complete covering surface at high dew point to separated oxide spots at grain boundaries at low dew point. At the low dew point Cr was not oxidized. Oxides with a low Mn/Si-ratio seems to be amorphous. The Si-oxides are especially located at grain boundaries, Mn-oxides tend to cover the surface. Oxides covering the steel surfaces are detrimental for subsequent procedures as hot dip galvanizing, painting and welding.
4
Husák, Roman, Hynek Hadraba, Zdeněk Chlup, Milan Heczko, Tomáš Kruml, and Viktor Puchý. "ODS EUROFER Steel Strengthened by Y-(Ce, Hf, La, Sc, and Zr) Complex Oxides." Metals 9, no. 11 (October 26, 2019): 1148. http://dx.doi.org/10.3390/met9111148.
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Oxide dispersion-strengthened (ODS) materials contain homogeneous dispersions of temperature-stable nano-oxides serving as obstacles for dislocations and further pinning of grain boundaries. The strategy for dispersion strengthening based on complex oxides (Y-Hf, -Zr, -Ce, -La) was developed in order to refine oxide dispersion to enhance the dispersion strengthening effect. In this work, the strengthening of EUROFER steel by complex oxides based on Y and elements of the IIIB group (lanthanum, scandium) and IVB group (cerium, hafnium, zirconium) was explored. Interparticle spacing as a dispersoid characteristic appeared to be an important factor in controlling the dispersion strengthening contribution to the yield strength of ODS EUROFER steels. The dispersoid size and average grain size of ODS EUROFER steel were altered in the ranges of 5–13 nm and 0.6–1.7 µm, respectively. Using this strategy, the yield strength of the prepared alloys varied between 550 MPa and 950 MPa depending on the doping element.
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Hilson, Gabrielle, Keith R. Hallam, and Peter E. J. Flewitt. "The Measurement of Stresses within Oxides Produced on Austenitic and Ferritic Steels Using Raman Spectroscopy." Materials Science Forum 524-525 (September 2006): 957–62. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.957.
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Raman spectroscopy has been used by various workers to provide a measure of the stresses within the oxides grown on metal substrates at high temperatures. In this paper, we consider thermally grown oxides produced on a Type 316 austenitic stainless steel and an iron 3% silicon ferritic steel. The oxides were grown in air at temperatures of 950oC and 650oC respectively over a range of times. These oxides have been characterised by producing cross-sections using focused ion beam milling. The variation of the Raman spectra wave number (He, Ne laser; λ = 633nm) for the oxides produced on the polycrystalline austenitic stainless steel and the ferritic steel were measured as a function of oxide thickness. This shift in wave number was a function of stress. For a fixed oxide thickness on the stainless steel substrate the specimen has been subject to a bending force. A back face strain gauge fixed to the metal substrate provided a measure of the applied strain. The peak wave number varied with applied strain. The results are discussed with respect to the potential to characterise the stresses produced in thermally grown oxides and as a tool to monitor applied stress.
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Cheng, Xia Wei, Zheng Yi Jiang, Guang Zheng Luo, Dong Bin Wei, and Liang Hao. "Study on Oxidation Behavior of Stainless Steels in Short Time." Applied Mechanics and Materials 633-634 (September 2014): 209–14. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.209.
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The various chemical compositions of stainless steels can result in complication of the formation of oxide scales in hot rolling process. The time for formation of tertiary oxide scale during finishing rolling is short. In the present study, the oxidation tests with short time period were carried out on eight stainless steel grades by Gleeble 3500 thermal mechanical simulator in a simulated water mist environment. Multi-layers of oxide scale have been developed on all the steel grades during short time oxidation. Internal and intergranular oxides were formed in the steel matrix underneath the inner spinel oxide layer. The cross section of the oxide scales were examined and measured by SEM to understand the oxide scale cross section morphology and thickness.
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Lee, Jae Hoon. "Mechanical and Microstructural Properties of Al-Added ODS Ferritic Steel." Advanced Materials Research 567 (September 2012): 49–53. http://dx.doi.org/10.4028/www.scientific.net/amr.567.49.
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18%Cr-oxide dispersion strengthened (ODS) ferritic steels with and without 5%Al have been produced by mechanical alloying and hot-extrusion. The microstructure of the ODS steels has been characterized by means of electron microscopy (SEM, TEM), showing that in the Al-added ODS steel, the semi-coherent and coherent oxide particles are about 75% and 10%, respectively. It was found that the coherency of oxide particles depends on the size of dispersed particles. Tensile tests performed between room temperature and 973 K denote that the ultimate tensile strength of Al-free ODS steel is higher than that of Al-added one. The ductility values of both materials are sufficiently high. Impact tests reveal that the ductile-to-brittle transition temperature of Al-free ODS steel are higher than that of Al-added ODS steel; however, the upper shelf energy of 18%Cr-ODS steel is substantially smaller in comparison to the Al-added one. It is considered that the difference in mechanical properties between Al-free and Al-added ODS steels is caused by the smaller, stable titania + yttria complex oxides dispersed in the Al-free ODS steel.
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Lee, Jae Hoon. "Oxidation of Oxide Dispersion Strengthened Steels: I. Influence of Alloy Composition." Advanced Materials Research 748 (August 2013): 86–90. http://dx.doi.org/10.4028/www.scientific.net/amr.748.86.
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Oxidation tests of 18%Cr-oxide dispersion strengthened (ODS) steels with and without 5%Al were carried out in air at 700900 °C for time period up to 540 h. No minor alloying elements affect the oxidation behavior and the Al concentration between these ODS steels is a main difference. Cr2O3and (Fe,Cr)3O4spinel oxides exist on the surface of 18Cr-ODS steel; however, the surface oxide of 18Cr5Al-ODS steel is comprised of only Al2O3. Oxidation resistance of the ODS steels exposed at 700 °C is much better than Incoloy800 of which the Cr content is larger and their oxidation behavior doesnt follow the aluminum content. These results suggest that oxide particles dispersion and grain refinement play a more critical role than alloy composition in the high-temperature oxidation resistance.
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MOON, SANGWOON, BOKLAE CHO, SUKMIN CHUNG, CHONGDO PARK, KIJEONG KIM, TAIHEE KANG, and BONGSOO KIM. "THE OPTIMAL FORMATION CONDITION OF CHROMIUM OXIDE THIN FILM ON STAINLESS-STEEL SURFACE." Surface Review and Letters 09, no. 01 (February 2002): 285–91. http://dx.doi.org/10.1142/s0218625x02002208.
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We investigated the various oxidation conditions of stainless-steel surface using synchrotron radiation photoemission spectroscopy. Stainless-steel samples are oxidized at 450–550°C in various oxygen partial pressures. Increasing the annealing temperature from 450°C to 550°C, the trivalent chromium concentration in the surface increased and iron oxides decreased. The PES spectra from stainless steels oxidized at 550°C show that there exists the critical oxygen partial pressure, [Formula: see text] Torr. Below this critical pressure, the oxide formed mainly consists of chromium oxide, while the oxide formed mainly consists of iron oxide above the critical pressure. The oxidation behavior is in good agreement with the Ellingham diagram (a free-energy/temperature diagram).
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Praig, Vera Gertraud, and Michael Stöger-Pollach. "Metallography of Low Alloy Cr-Mn Hot-Rolled Steel and Quantitative Evaluation of Grain Boundary- and Internal Oxides by TEM." Materials Science Forum 782 (April 2014): 284–87. http://dx.doi.org/10.4028/www.scientific.net/msf.782.284.
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Alloy elements undergo complex diffusion and segregation processes during steel production. Oxygen diffuses into the steel matrix and forms oxides at the surface (called scale), at the grain boundaries and within the grains. In our work we present assemblies and composition of various oxides found at the grain boundaries and within the grains of a low alloy Mn-Cr hot-rolled steel sheet. We utilise metallographic means (surface etching) and transmission electron microscopy (TEM). After etching we observe four zones of different composition: (i) the scale, followed by a decarburised metallic layer with (ii) oxidised grain boundaries, (iii) non-oxidised grain boundaries and last, (iv) the bulk. Via TEM, we analyse alloy element oxides at grain boundaries and within the grains with high spatial resolution. At the grain boundaries and within the grains we find oxides, such as Mn- or Cr oxides, rather than binary oxides (e.g. Fe-Mn- and Fe-Cr oxides) or even more complex oxides, such as Fe-Mn-Cr oxides. The oxide species found lie next to- or embedded amongst one another.
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Niu, Li Bin, and Takuya Shibata. "Evaluation on the High-Temperature Oxidation Behavior of HP Steam Turbine Rotor Materials." Advanced Materials Research 750-752 (August 2013): 420–25. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.420.
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High-temperature oxidation behaviors of super-clean 9CrMoV steel and 1CrMoV steel for HP steam turbine rotor materials were investigated. The super-clean 9CrMoV steel showed a superior high-temperature oxidation resistance with very small oxidation rates even though at 630°C, because the oxidation was restrained by the Cr-oxides formed near the base metal. On the other hand, the oxide scales formed on the 1CrMoV steel were composed of Fe-oxides, and the oxidation rate increased remarkably at the temperatures above 610°C.
12
Li, Hui Gai, Yue Gong, Cun Bo Yang, Shao Bo Zheng, and Qi Jie Zhai. "Structure of TiOx Precipitated during Solidification of Steel." Advanced Materials Research 341-342 (September 2011): 85–88. http://dx.doi.org/10.4028/www.scientific.net/amr.341-342.85.
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Various Ti oxides formation potential was analysised by thermodynamics during solidification of steel. It was found that Ti3O5 is the most stable one among all the types of Ti oxides. The effect of Mn element on the structure of Ti oxide was analysised by some experiments. The structure of Ti oxide without Mn is Ti3O5, and the inclusion, which contains some content of Mn, is Ti2O3 with rhombohedra structure. It is assumed that, [Ti] and [O] in liquid steel precipitated in form of Ti3O5. During the cooling process of solid steel, Ti3O5 reacted with [Mn], and exsited in form of Ti2O3 and MnO complex inclusion, which is advantageous for the nucleation of IGF.
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Zhao, Dan, Jie Yun Cheng, Jing Chen, Hui Gai Li, and Shao Bo Zheng. "Thermodynamics of Amorphous Silicon Oxides in Sub-Rapid Solidified Low Carbon Steel." Materials Science Forum 816 (April 2015): 788–94. http://dx.doi.org/10.4028/www.scientific.net/msf.816.788.
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Strip casting technology leads a new revolutionary change for steel industry, which solidification rate could be 100-1000 K/s. The study on the size and structure of deoxidation products from the sub-rapid solidification will be of great significant in promoting the mechanical properties of the strip continuous casting steels. In the paper, the silicon oxide inclusions precipitated in sub-rapid solidified low carbon steel were investigated by transmission electron microscopy. The experimental results indicated that a large number of spherical silicon oxides were dispersed as amorphous state, and the size range was in hundreds nanometers. According to the thermodynamic calculation and inference, the silicon oxides would precipitate during the sub-rapid solidification of low carbon steel. SiO2, which structure is as approximate “liquid” and the melting temperature has been reduced under nanoeffect, has been frozen in amorphous state under high solidification rate. Amorphous SiO2 precipitated in steel may be due to the structural relaxation caused by high viscosity. The larger average size of amorphous SiO2 was detected at higher solidification rate, which is attributed to the cause to the higher hardening rate.
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Szpunar, Jerzy A., and Bae Kyun Kim. "High Temperature Oxidation of Steel; New Description of Structure and Properties of Oxide." Materials Science Forum 539-543 (March 2007): 223–27. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.223.
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The quality of steel sheets is strongly affected by the surface defects that can be generated during hot rolling and are often related to scales removal operation. These defects are related to rather complex high temperature oxidation processes. In order to reduce an occurrence of the defects, it is necessary to understand better the formation of iron oxides during high temperature oxidation, the structure of the interfaces with the substrate and between different oxide phases. However, due to the lack of good experimental research tools details of iron oxide microstructures were not investigated. Conventional methods, such as backscattered electron images or fractography can only provide general characteristics of microstructures like grain morphology and grain size. In this paper the microstructure, phase distribution and texture in oxide formed during high temperature oxidation of iron and low carbon steels are investigated. The oxide microstructures are characterized by orientation imaging microscopy (OIM) on the cross-sectional area of the oxide layers. It is demonstrated that OIM using electron backscattered diffraction (EBSD) techniques, can be used to distinguish grains having different phase composition and orientation and can become invaluable tool for visualizing the oxide microstructure, texture and also can be used to study oxide defects. The three different iron oxides phases can be distinguished and the characteristics of oxides with different oxidation histories compared The characteristics of high temperature oxidation microstructure of iron are presented with description of iron oxide defects and cracking as well as the illustration of the interfacial microstructure between the layered iron oxides.
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Yadav, Poonam, Sang Hwan Bak, and Dong Bok Lee. "Corrosion of Fe-2.25Cr-1.6W-0.1Mo Steels in Na2SO4 Salts at 800 and 900°C." Applied Mechanics and Materials 752-753 (April 2015): 22–25. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.22.
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The ASTM T23 steel with a composition of Fe-2.25Cr-1.6W-0.1Mo in wt.% was corroded in the Na2SO4 salt at 800 and at 900°C, and its corrosion behavior was studied. It formed thick, porous oxide scales that consisted primarily of outer Fe-rich oxides and inner (Fe, Cr)-rich oxides. The corrosion of the T23 steel progressed mainly via oxidation.
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Li, Huaying, and Aichun Zhao. "Pickling Behavior of Duplex Stainless Steel 2205 in Hydrochloric Acid Solution." Advances in Materials Science and Engineering 2019 (February 25, 2019): 1–6. http://dx.doi.org/10.1155/2019/9754528.
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The oxide-scale structure and pickling behavior of oxided 2205 duplex stainless steel in the electrolytes containing hydrochloric acid were investigated. The oxide scales mainly consist of two layers: the outer layer is dense Fe2O3, and the inner granular is FeCr2O4 spinel. During the pickling process, pittings form around the boundaries of FeCr2O4 particles or interfaces of two kinds of oxides, which results in that the electrolyte can directly react with the chromium-depleted layer along the pittings to produce an “undercut” effect so that the pickling efficiency is improved markedly. The pickling mechanism was discussed, and the model was established.
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Wang, Jian Ming, Yan Liu, Chun Lin He, and Yang Liu. "Effect of Nanometer Calcium and Magnesium Oxides Addition on the Inclusions in the Cast Microstructure of X80 Pipeline Steel." Applied Mechanics and Materials 401-403 (September 2013): 606–9. http://dx.doi.org/10.4028/www.scientific.net/amm.401-403.606.
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Nanometer calcium and magnesium oxides were added into molten steel by the carrier method in the experiment. The experiment takes the X80 pipeline steel as the research object and analyses the effect of nanometer calcium and magnesium oxides addition on the inclusions in the cast microstructure of the X80 pipeline steel. The scanning electron microscope (SEM) was used to analyse the morphology and distribution of the inclusions in the cast microstructure of the X80 pipeline steel. The results reveal that there are a small amount of inclusions in the sample of no nanometer oxides addition. With the amount of the nanoMgO oxide addition rising, the number of the inclusions in the sample firstly increases and then decreases gradually. When adding 0.05 wt% nanoMgO or CaO oxides, the size of the inclusions is big and the aggregation phenomenon appears. When adding 0.02 wt% nanoMgO or CaO oxides, the number of the inclusions in the cast microstructure is the most, whose size is smaller, about 2~4 μm and the inclusions are the most uniformly distributed.
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Kozuh, S., L. Vrsalovic, M. Gojic, S. Gudic, and B. Kosec. "Comparison of the corrosion behavior and surface morphology of NiTi alloy and stainless steels in sodium chloride solution." Journal of Mining and Metallurgy, Section B: Metallurgy 52, no. 1 (2016): 53–61. http://dx.doi.org/10.2298/jmmb150129003k.
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The corrosion behavior of NiTi alloy and stainless steels (AISI 316L and X2CrNiMoN22-5-3) in 0.9% sodium chloride (0.154 moll-1) solution was investigated using open circuit potential measurements, potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Microstructural analyses before and after electrochemical tests were performed with the scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). The lowest corrosion current density has NiTi alloy and the extent of the passive range increased in the order AISI 316L stainless steel < NiTi alloy < X2CrNiMoN22-5-3 duplex stainless steel. The oxide film formed on all samples has a double-layer structure consisting of a barrier-type inner layer and a porous outer layer. Oxide films formed on the surface of steels mainly contains iron oxides and chromium oxide, while the surface film of the NiTi alloy mainly contains TiO2 oxide.
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Shu, Wei, Xue Min Wang, Cheng Jia Shang, and Xin Lai He. "The Influence of Oxide Inclusion on Austenite Grain Size and Heat Affected Zone Toughness for Low Carbon Steels." Materials Science Forum 715-716 (April 2012): 617–22. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.617.
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The low carbon steels were smelted with special oxide introduction technique and the HAZ properties has been studied with thermal simulation. The optical microscope, SEM and TEM were used to analyze the composition, size and distribution of the inclusions, and the mechanical properties after thermal simulation were also investigated. The influence of oxide inclusions on the austenite grain size was also studied. The results show that after the smelting the inclusion is complex, in the core is Ti oxides about 1-3 micron and around it is MnS. When the reheat temperature is below 1000, the size of austenite grain is the same for experimental steel and base steel. However, when the reheat temperature is over than 1100, the size of austenite grains in experimental steel is one third of that in base steels. After thermal simulation, with thet8/5increasing the toughness of HAZ decreased. The austnite grain size also increased. The microstructure is composed of intergranular ferrite and intragranular acicular ferrite. Therefore by introducing the fine oxide inclusion to the steel the austenite grain was refined and during the phase transformation the acicular ferrite formed at inclusions at first. These two factors are the main causes to improve the toughness of heat affected zone for steels produced by oxide metallurgy technique.
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Bongiorno, Valeria, Roberto Spotorno, Daniele Paravidino, and Paolo Piccardo. "On the High-Temperature Oxidation and Area Specific Resistance of New Commercial Ferritic Stainless Steels." Metals 11, no. 3 (March 1, 2021): 405. http://dx.doi.org/10.3390/met11030405.
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Two commercial ferritic stainless steels (FSSs), referred to as Steel A and Steel B, designed for specific high-temperature applications, were tested in static air for 2000 h at 750 °C to evaluate their potential as base materials for interconnects (ICs) in Intermediate Temperature Solid Oxide Fuel Cell stacks (IT-SOFCs). Their oxidation behavior was studied through weight gain and Area Specific Resistance (ASR) measurements. Additionally, the oxide scales developed on their surfaces were characterized by X-ray Diffraction (XRD), Micro-Raman Spectroscopy (μ-RS), Scanning Electron Microscopy, and Energy Dispersive X-ray Fluorescence Spectroscopy (SEM-EDS). The evolution of oxide composition, structure, and electrical conductivity in response to aging was determined. Comparing the results with those on AISI 441 FSS, steels A and B showed a comparable weight gain but higher ASR values that are required by the application. According to the authors, Steel A and B compositions need an adjustment (i.e., a plain substitution of the elements which form insulant oxides or a marginal modification in their content) to form a thermally grown oxide (TGO) with the acceptable ASR level.
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Maderthaner, Magdalena, Alexander Jarosik, Gerhard Angeli, and Roland Haubner. "3rd Generation Hot-Dip Galvanized Steel Sheet for Automobile Manufacturing - Interface Reactions between Zinc and Metal Oxide." Key Engineering Materials 742 (July 2017): 463–70. http://dx.doi.org/10.4028/www.scientific.net/kem.742.463.
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There is a growing demand for Advanced High Strength Steels (AHSS) in the automotive industry owing to their high specific strength and good formability. The mechanical properties satisfy the demands for improved passenger safety and decreased vehicle weight due to thinner cross sections. Hot-dip galvanizing is a common procedure to prevent corrosion of steel, galvanized steel forms the basis for further processing like organic coating. Industrially, the steel strip is annealed at 840 °C in 5 % H2 in N2 at a dew point (DP) of -30 °C. These conditions are reducing for Fe, but oxidizing for oxygen-affine alloying elements as Mn, Si and Cr. These ignoble elements form an external, covering oxide layer on the steel surface, which exhibits poor wettability for the Zn(Al, Fe)-bath. The liquid Zn(Al, Fe) has a temperature of 460 °C and contains 0,2 wt% Al to form a Fe2Al5-xZnx-layer to inhibit the growth of Fe-Zn-intermetallics. Along with the increased amount of alloying elements to improve strength and ductility of AHSS the evolving oxide layer after annealing at the steel surface deteriorates hot-dip galvanizing. The question arises what happens to the surface oxides during immersion in the Zn(Fe, Al)-bath. For this purpose annealed as well as annealed and galvanized 0.8Si-AHSS and 1.5Si-AHSS were compared by glow discharge optical emission spectroscopy (GD-OES) depth profiles. Galvanized specimens show fewer oxides at the steel-zinc-interface as annealed specimens. A possible explanation is an aluminothermic reduction of oxides by 0.2 wt% dissolved Al in the Zn(Al, Fe)-bath. Al is thermodynamically more affine to oxygen than Mn and Si and may reduce Mn- and Si-oxides. An alternative theory is the dissolution of Fe in Zn during reactive wetting, as a side effect the oxides are rinsed off too. Additionally, the influence of DP was investigated. According to Wagner’s theory of selective oxidation, a higher amount of oxygen in the annealing atmosphere leads to internal oxidation of the alloying elements. Experiments were carried out with 0.8Si-AHSS and 1.5Si-AHSS by altering the DP during annealing from -30 °C (380 ppm H2O) to 0 °C (6000 ppm H2O). Oxidation mode changed from external (DP -30 °C) to internal oxidation along grain boundaries (DP 0 °C), as predicted by Wagner. These oxide-free surface provides good reactivity to enhance reactive wetting with the Zn(Fe, Al)-bath and form a dense Fe2Al5-xZnx-layer.
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Riffard, Frédéric, Henri Buscail, F. Rabaste, Eric Caudron, Régis Cueff, Christophe Issartel, N. Karimi, and Sébastien Perrier. "Manganese Effect on Isothermal High Temperature Oxidation Behaviour of AISI 304 Stainless Steel." Materials Science Forum 595-598 (September 2008): 1127–34. http://dx.doi.org/10.4028/www.scientific.net/msf.595-598.1127.
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Chromia-forming steels are excellent candidates to resist to high temperature oxidizing atmospheres because they form protective oxide scales. The oxide scale growth mechanisms are studied by exposing AISI 304 stainless steel to high temperature conditions in air, and the analyses were carried out by means of thermogravimetry and in situ X-rays diffraction. The in situ XRD analyses carried out during high temperature AISI 304 steel oxidation in air reveals the accelerated growth of iron-containing oxides such as hematite Fe2O3 and iron-chromite FeCr2O4, when the initial germination of the oxide layer contains the presence of a manganese-containing spinel compound (1000°C). When the initial growth shows the only chromia formation (800°C), hematite formation appears differed in time. Protection against corrosion is thus increased when the initial germination of manganese-containing spinel oxide is inhibited in the oxide scale.
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Karimi, N., Henri Buscail, Frédéric Riffard, F. Rabaste, Régis Cueff, Christophe Issartel, Eric Caudron, and Sébastien Perrier. "Effect of Lanthanum Sol-Gel Coating on the Oxidation Behaviour of the AISI 304 Steel at 1000°C." Materials Science Forum 595-598 (September 2008): 733–41. http://dx.doi.org/10.4028/www.scientific.net/msf.595-598.733.
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The aim of the present work is to investigate the effect of Lanthanum surface addition on the oxidation behaviour of the AISI 304 stainless steel, in air, at 1000°C. The in situ X-ray diffraction (XRD) analyses on the blank steel reveal that after the first 10h oxidation, a change in the structural composition of the oxide scale occurs. During the first ten hours oxidation an initial growth of chromia and Mn1,5Cr1,5O4 is observed. After 10 h oxidation, chromia is not detected anymore and iron-containing oxides such as hematite (Fe2O3) and iron chromite (FeCr2O4) are observed in the outer part of the scale. With blank AISI 304 specimens, the iron-containing oxides are generally not very protective and show severe spallation during cooling to room temperature due to thermal stresses. They do not allow a good adherence of the corrosion layer under thermal cycling. On the Lanthanum coated AISI 304 Stainless Steel the oxidation rate is 10 times lower. In situ XRD analyses show the absence of iron containing oxides. It reveals the formation of a fine convoluted Cr2O3 layer associated with the formation of the mixed oxides Mn1,5Cr1,5O4 and LaCrO3. LaCrO3 is found to be located at the oxide/steel interface. Our results show that, even though the scale formed under isothermal conditions is not composed of iron containing oxides, Lanthanum sol-gel coating does not prevent spallation during thermal cycling at 1000°C.
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Tyusenkov, A. S., A. V. Rubtsov, and R. R. Tlyasheva. "Heat Resistance of Certain Structural Steels." Solid State Phenomena 265 (September 2017): 868–72. http://dx.doi.org/10.4028/www.scientific.net/ssp.265.868.
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Heat-resistance (scale resistance) is the steel corrosion fastness in dry gas at high temperatures. At the temperatures over 570 °С, the ferrous alloys oxidize, as ferric oxide (wustite) with simple cubic lattice appears on the metal surface. Such oxide lacks oxygen atoms (omission solid solution) and does not interfere with the diffusion between metal and oxygen. As a result of this process the brittle oxide-scale develops and the loss of metal increases. In order to increase the heat-resistance of steel, different alloying elements are included into its composition, forming oxides with the tight structure of crystal lattice. In this paper we’ve investigated the heat-resistance of some structural steels and analyzed their corrosion resistance in the high temperature aggressive environments of chemical productions.
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Li, Weijuan, Haijian Xu, Xiaochun Sha, Jingsong Meng, and Zhaodong Wang. "Microstructure and Mechanical Properties of 14Cr-ODS Steels with Zr Addition." High Temperature Materials and Processes 38, no. 2019 (February 25, 2019): 404–10. http://dx.doi.org/10.1515/htmp-2018-0067.
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AbstractIn this study, oxide dispersion strengthened (ODS) ferritic steels with nominal composition of Fe–14Cr–2W–0.35Y2O3 (14Cr non Zr-ODS) and Fe–14Cr–2W–0.3Zr–0.35Y2O3 (14Cr–Zr-ODS) were fabricated by mechanical alloying (MA) and hot isostatic pressing (HIP) technique to explore the impact of Zr addition on the microstructure and mechanical properties of 14Cr-ODS steels. Microstructure characterization revealed that Zr addition led to the formation of finer oxides, which was identified as Y4Zr3O12, with denser dispersion in the matrix. The ultimate tensile strength (UTS) of the non Zr-ODS steel is about 1201 MPa, but UTS of the Zr-ODS steel increases to1372 MPa, indicating the enhancement of mechanical properties by Zr addition.
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Nishimura, Toshiyasu. "Corrosion Resistance of Si and Al-Bearing Ultrafine Grained Weathering Steel." Materials Science Forum 475-479 (January 2005): 55–60. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.55.
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The iron rust phase has been analyzed by using EPMA, TEM and EIS after simulating marine corrosion tests. The ultrafine grained (UFG) weathering steel containing Si and Al showed higher corrosion resistance than carbon steel in the test. Si and Al were identified as Si 2+ and Al 3+ in the complex oxide of inner rust by EPMA and TEM. It was demonstrated by EIS that the resistance at the low frequency region corresponded to that of corrosion reaction of rusted steels (Rt). The Rt value of this steel increased after the continuous formation of inner rust, which implied that Si and Al took part in the conversion of complex oxides into fine structure that prevented the penetration of Cl ions.
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Donlon, William T., and William E. Dowling. "Identification of non-martensitic transformation products(NMTP) in a carburized 8620 steel." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 526–27. http://dx.doi.org/10.1017/s0424820100139007.
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Additions of Cr and Mn to steel are intended to increase hardenability (the ability to form martensite on cooling from austenite) and thereby improve the mechanical properties. However, conventional gas carburization of alloy steels containing Cr and Mn as well as Si will produce oxides of these elements (internal oxidation) near the surface (due to the oxygen potential of the carburizing atmosphere). Additionally, the oxidation of these elements locally reduces the hardenability of the alloy, creating the potential to produce non-martensitic transformation products (NMTP) near the surface. These oxides and the associated NMTP have been shown to decrease the fatigue resistance of carburized steels if they are not removed by subsequent machining operations. The objective of this study is to characterize the oxides, identify the NMTP and assess the degree of local alloy depletion in a carburized 8620 steel (0.21 C, 0.93 Mn, 0.023 S, 0.12 Si, 0.49 Cr, 0.38 Ni and 0.17 Mo).
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Garza-Montes-de-Oca, Nelson F., Arnulfo Treviño-Cubero, Javier H. Ramírez-Ramírez, Francisco A. Pérez-González, Rafael D. Mercado-Solís, and Rafael Colás. "On the spallation of oxide scales in high-strength low-alloy (HSLA) hot-rolled steels." Corrosion Reviews 38, no. 4 (August 27, 2020): 355–64. http://dx.doi.org/10.1515/corrrev-2019-0070.
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AbstractIn this work, results on the causes that could promote the abnormal spallation of the oxides formed on the surface of high-strength low-alloy (HSLA) steels are presented. By means of Rietveld refining of X-ray diffraction spectra, scanning electron microscopy analyses and calculations, it was found that the value of the thermal stress experienced by the oxide scale reached a maximum when the oxide scale was comprised by 65% wt magnetite Fe3O4 and 24% wt wustite FeO this, due to the incomplete transformation of the latter phase to Fe3O4 and α-Fe from cooling from 670 °C to ambient temperature. Contrarily, it was found that when a balance in the amount of Fe3O4 and FeO was 46.4 and 46.5%wt respectively, the calculated thermal stress was reduced, and oxide spallation was not that severe. The reasons for oxide scale detachment from the surface of the steels are explained in terms of the adhesion energy of the bulk oxide scale, the amount of magnetite Fe3O4 present in the oxides and the chemical composition of the steel particularly the elements chromium and titanium.
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Gupta, Rajeev Kumar, Manisha Malviya, Chandrabhan Verma, Neeraj K. Gupta, and M. A. Quraishi. "Pyridine-based functionalized graphene oxides as a new class of corrosion inhibitors for mild steel: an experimental and DFT approach." RSC Advances 7, no. 62 (2017): 39063–74. http://dx.doi.org/10.1039/c7ra05825j.
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Two functionalized graphene oxides, diazo pyridine functionalized graphene oxide and diamino pyridine functionalized graphene oxide, were synthesised and evaluated as corrosion inhibitors on mild steel in 1 M hydrochloric acid.
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Chen, Zhiyuan, Lijun Wang, Ziyou Yu, Fushen Li, Zaihong Sun, Hailei Zhao, and Kuo Chih Chou. "Corrosion Process of Stainless Steel 441 with Heated Steam at 1,000 °C." High Temperature Materials and Processes 36, no. 7 (July 26, 2017): 717–24. http://dx.doi.org/10.1515/htmp-2015-0238.
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AbstractStainless steel 441 was oxidized in water vapor containing atmospheres at 1,000 °C to study the contrary effects of water vapor on the oxidization process. The steel in 3.5 vol. % H2O containing atmosphere exhibited an relatively strong protective behavior. The reason was that the densification of the chromium oxide scale was promoted due to the sintering of the oxide grains via Cr-containing species vapor. But the oxidation of the steel in 11.5 ~ 15.6 vol. % H2O containing atmosphere followed a non-protective breakaway oxidation due to the breakage of the dense scale by “bubbles” and the formation of iron-rich oxides layer. Experimental result shows that the growth stress increased about 2 GPa during the first 70 ks in wet oxidizing atmosphere. The relatively slow increase of the oxides scale growth stress could be release in water vapor containing atmosphere.
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Cao, Zhong Lu, Makoto Hibino, and Hiroki Goda. "Effect of Steel Surface Conditions on the Macro-Cell Polarization Behavior of Reinforcing Steel." Applied Mechanics and Materials 584-586 (July 2014): 1771–79. http://dx.doi.org/10.4028/www.scientific.net/amm.584-586.1771.
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The effect of steel surface conditions on the macro-cell polarization behavior of reinforcing steels embedded in cement mortar was investigated by comparing and analyzing the macro-cell current density and macro-cell polarization ratio of steels. The results indicated that steel surface conditions played an important role in controlling the macro-cell corrosion and polarization. The polished or pre-rusted surface had a better corrosion resistance to inhibit the flow of macro-cell current than the scaled surface that formed in the production process. Compared to the polished surface, the presence of mill scale or rust oxides on the surface of anodic steel could reduce the macro-cell polarization ratio of anode.
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Lad’yanov, V. I., G. A. Dorofeev, E. V. Kuz’minykh, V. A. Karev, and A. N. Lubnin. "ALUMINOBAROTHERMIC SYNTHESIS OF HIGH-NITROGEN STEEL." Izvestiya. Ferrous Metallurgy 62, no. 2 (March 30, 2019): 154–62. http://dx.doi.org/10.17073/0368-0797-2019-2-154-162.
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High-nitrogen austenitic steels are promising materials, combining high strength, plasticity and corrosion resistance properties. However, to produce high-nitrogen steel by conventional metallurgical methods under high nitrogen pressure, powerful and complex metallurgical equipment is required. From energy-saving viewpoint, an alternative and simpler method for producing high-nitrogen steels can be aluminothermy (reduction of metal oxides by metallic aluminum) under nitrogen pressure. Thermodynamic modeling of aluminothermic reactions in a nitrogen atmosphere was carried out by the authors. Aluminothermy under nitrogen pressure was used to produce high-nitrogen nickel-free Cr – N and Cr – Mn – N stainless steels with a nitrogen content of about 1 %. Microstructure (X-ray diffraction, metallography and transmission electron microscopy techniques) and mechanical properties were examined. Thermodynamic analysis has shown that the aluminothermic reduction reactions do not go to the end. The most important parameter of the synthesis is the ratio of Al and oxygen in the charge, the correct choice of which provides a compromise between completeness of oxides reduction, content of aluminum and oxygen in steel (the degree of deoxidation), and its contamination with aluminum nitride. Cr – N steel ingots in the cast state had the structure of nitrogen perlite (ferrite-nitride mixture), and Cr – Mn – N steel – ferrite-austenite structure with attributes of austenite discontinuous decomposition with Cr2 N precipitations. Quenching resulted in complete austenization of both steels. The compliance of the austenite lattice parameter obtained from the diffractograms for quenched Cr – Mn – N steel with the parameter predicted from the known concentration dependence for Cr – Mn – N austenitic steels indicated that all alloying elements (including nitrogen) were dissolved in austenite during aging at quenching temperature and fixed in the solid solution by quenching. Study of the mechanical properties of quenched Cr – Mn – N steel has shown a combination of high strength and ductility. It is concluded that by the aluminothermic method a high-nitrogen steel can be obtained, which, by mechanical properties, is not inferior to industrial steel – analog manufacted by electroslag remelting under nitrogen pressure.
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Hao, Mingxin, Bin Sun, and Hao Wang. "High-Temperature Oxidation Behavior of Fe–1Cr–0.2Si Steel." Materials 13, no. 3 (January 21, 2020): 509. http://dx.doi.org/10.3390/ma13030509.
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In the case of Fe–1Cr–0.2Si steel, tube furnace oxidation was carried out for 120 min and 30 min. These studies, along with the high-temperature oxidation behavior of Fe–1Cr–0.2Si steel, were examined from 700 to 1100 °C. It has been observed that with an increase in the oxidation time, the oxidation weight gain per unit area of Fe–1Cr–0.2Si steel changed from a linear to a parabolic relationship. The time was shortened when the oxidation phase was linear. When the oxidation temperature exceeded 900 °C, the value of WTransition decreased, and the oxidation rule changed. It could be considered that overall, the iron oxide structure of Fe–1Cr–0.2Si steel is divided into two layers. The formation of an outer oxide of iron is mainly caused by the outward diffusion of cation, while the inward diffusion of O ion forms the inner oxides of chromium and silicon. As the temperature increases, the thickness of the outer iron oxide gradually increases, and the thickness ratio of the inner mixed layers of chromium- and silicon-rich oxides decreases; however, the degree of enrichment of Cr and Si in the mixed layer increases. After high-temperature oxidation, Cr and Si did not form a composite oxide but were mechanically mixed in the form of FeCr2O4 and Fe2SiO4, and no significant delamination occurred.
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Zhang, L. N., X. Zhang, Y. Ma, and D. L. Liu. "TEM Observation on Nano-Precipitation of Plain Low Carbon Steel by CSP." Materials Science Forum 475-479 (January 2005): 101–4. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.101.
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Plain low carbon steel produced by compact strip production (CSP) process was analyzed using TEM, EELS and XEDS. Nano-sized oxides and sulfides were observed in the steel. The nano-oxides are mainly ferrospinel of <20nm in size, and the nano-sulfides are MnS and FeS particles with size of 20-100 nm. They distributed both in grains and at grain boundaries. These nano precipitates could form in cast slab before heavy deformation by rolling process. It is proposed that besides the grain refinement, the nano-pricipitation plays an important role in yield strength enhancement. This mechanism may provide a new approach to strengthen plain low carbon steels.
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Dawson, Karl, and Gordon J. Tatlock. "Characterisation of nanosized oxides in ODM401 oxide dispersion strengthened steel." Journal of Nuclear Materials 444, no. 1-3 (January 2014): 252–60. http://dx.doi.org/10.1016/j.jnucmat.2013.10.003.
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Voleník, K., J. Lettner, F. Hanousek, J. Dubsky, and B. Kolman. "Oxides in plasma-sprayed chromium steel." Journal of Thermal Spray Technology 6, no. 3 (September 1997): 327–34. http://dx.doi.org/10.1007/s11666-997-0067-8.
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Cai, Yangchuan, Zhen Luo, Zunyue Huang, and Yida Zeng. "Influence of Oxides on Microstructures and Mechanical Properties of High-Strength Steel Weld Joint." High Temperature Materials and Processes 35, no. 10 (November 1, 2016): 1047–53. http://dx.doi.org/10.1515/htmp-2015-0151.
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AbstractA comprehensive investigation was conducted into the effect of oxides on penetrations, microstructures and mechanical properties of BS700MC super steel weld bead. Boron oxide changed the penetration of weld bead by changing the Marangoni convection in the weld pool and contracting the welding arc. Chromium oxide only changed the Marangoni convection in the weld pool to increase the penetration of super steel. Thus, the super steel weld bead has higher penetration coated with flux boron oxide than that coated with chromium oxide. In other words, the activating flux TIG (A-TIG) welding with flux boron oxide has less welding heat input than the A-TIG welding with flux chromium oxide. As a result, on the one hand, there existed more fine and homogeneous acicular ferrites in the microstructure of welding heat-affected zone when the super steel was welded by A-TIG with flux boron oxide. Thus, the weld beads have higher value of low-temperature impact toughness. On the other hand, the softening degree of welding heat-affected zone, welded by A-TIG with flux boron oxide, will be decreased for the minimum value of welding heat input.
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Bulko, B., J. Kijac, and T. Borovský. "The Influence of Chemical Composition of Steel on Steel Desulphurization." Archives of Metallurgy and Materials 56, no. 3 (September 1, 2011): 605–9. http://dx.doi.org/10.2478/v10172-011-0065-1.
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The Influence of Chemical Composition of Steel on Steel Desulphurization The steel desulphurization in ladle furnace depends on temperature, oxygen and sulphur content in the steel, but mainly on chemical composition and physical properties of slag. Necessary requirement for effective desulphurization is also minimum content of easily reducible oxides in the slag. There are many correlations for expression of slag desulphurization capability, where their functional dependency on each other can be found, mainly between sulphur distribution coefficient, optical basicity, basicity, sulphide capacity, desulphurisation potential of slag and also calcium - aluminate ratio of oxides in slag or content of easily reducible oxides in slag. This work presents statistical and graphical correlation between manganese and slag parameters using the set of approximately 768 heats and based on these, the optimal parameters for slag desulphurization capability are expressed especially for steel grades internally marked as OR1, OR3 in Železiarne Podbrezová, a.s. Steel grades OR1 and OR3 were chosen because of difference in manganese content with similar chemical composition of other elements. The MnO content in the slag is one of the most important parameters. Despite the higher scatter of obtained values, the distribution coefficient of sulphur (Ls) is one of the wide range of parameters for whom exists very close dependence on MnO content in slag.
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Cai, Zhengyu, and Hui Kong. "Inclusion and Microstructure Characteristics in a Steel Sample with TiO2 Nanoparticle Addition and Mg Treatment." Metals 9, no. 2 (February 1, 2019): 171. http://dx.doi.org/10.3390/met9020171.
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TiO2 nanoparticles and Mg alloy were added to molten steel in sequence to investigate the inclusion and microstructure characteristics. Compared with a non-treated sample, these additives resulted in the formation of Ti–Mg-bearing inclusions, which proves that the additives were valid. The size evolution from nanometer-scale TiO2 to micrometer-scale oxides hints at the agglomeration and growth of the TiO2 nanoparticles, which is due to the possible formation of a liquid-capillary force, the decomposition reaction of TiO2, and the higher Gibbs free energy of the nanoparticle. Furthermore, the statistical analysis of the oxides indicated that with the addition of the TiO2 nanoparticles and Mg alloy, the oxides were refined and their density was higher. Few pure MnS were observed in the treated sample. This is due to the fact that most oxides separated out in the liquid region at 1873 K based on the oxide composition and the calculated Al2O3–Ti3O5–MgO phase diagram. Thus, MnS preferred to segregate on them during solidification. After etching, it was found that the Ti–Mg-bearing oxide can induce the nucleation of intragranular acicular ferrites. The appearance of these acicular ferrites was not observed in the non-treated sample. This comparison indicates the effectiveness of the external adding method in oxide metallurgy.
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Parshin, Sergey G. "Metallurgical Effect of Rare-Earth Lanthanum Fluoride and Boride in the Composite Coating of Wires in the Arc Welding of Bainitic-Martensitic and Austenitic Steel." Metals 10, no. 10 (October 6, 2020): 1334. http://dx.doi.org/10.3390/met10101334.
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For arc welding of high-strength and cold-resistant steels, the author developed an advanced design of steel wire with a micro-composite coating of a nickel matrix and nanoparticles of LaF3 and LaB6, which improves the metallurgical influence of rare-earth elements (REE) and forms refractory sulphides and oxides of REE, as well as boron nitride. The addition of 0.1–0.3 wt% La in the weld pool leads to an increase in the content of the refractory compounds La2O3, LaO2, and LaS, and to the reduction in the content of the low-melting and brittle oxides and sulphides SiO2, SiO, MnO, MnS, and SiS. The use of steel wire with the composite coating of LaF3 and LaB6 allows for microstructural refinement when welding S960QL bainitic-martensitic steel and X70 API bainitic steel, and increases the impact toughness of the welds by 1.17–1.6 times.
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Yang, Jian Hua, and Song Li. "Characterization of Surface Composition and Microstructure of H21 Steel Implanted Using Masking Ti-Implantation." Advanced Materials Research 228-229 (April 2011): 130–34. http://dx.doi.org/10.4028/www.scientific.net/amr.228-229.130.
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Ti ions were implanted into H21 steel to improve the surface structure of oxides in H21 steel. The wear characteristics of the implanted steel was measured and compared to the performance of the un-implanted steel by a line-cutting apparatus and an optical interference microscope. The Ti concentration depth profile of the implanted steel was measured by Rutherford backscattering spectroscopy (RBS). The structure and composition of oxides were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The results showed that the improved wear resistance of the implanted steel was mainly due to the structure and composition changes of the surface oxides after Ti ion implantation.
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Zhu, Tengwei, Feng Huang, Jing Liu, Qian Hu, and Wei Li. "Effects of inclusion on corrosion resistance of weathering steel in simulated industrial atmosphere." Anti-Corrosion Methods and Materials 63, no. 6 (November 7, 2016): 490–98. http://dx.doi.org/10.1108/acmm-05-2015-1538.
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Purpose This paper aims to investigate the atmospheric corrosion mechanism of structural materials to develop more advanced corrosion-control technologies and cost-reduction strategies. As a second phase in steels, the non-metallic oxide inclusions are considered to not only affect the mechanical properties of steel but also the corrosion resistance of steel. So, an important research goal in this paper is to investigate the indoor accelerated corrosion kinetics of Q450NQR1 weathering steel, analyzing the galvanic polarity of different inclusions in electrochemical corrosion microcell between the inclusion and steel matrix and then elucidating the influence mechanism of inclusions on corrosion resistance of weathering steel. Design/methodology/approach Two methods of inclusion modification are usually used to improve the properties of weathering steel: one is calcium treatment on aluminum killed steel and the other one is rare earth (RE) modification. Wet/dry cyclic immersion corrosion test field emission scanning electron microscopy (FE-SEM) metallographic optical microscope. Findings The indoor accelerated corrosion kinetics of Q450NQR1 weathering steel could be divided into two stages with different log (thickness loss, D)-log (time, t) fitting functions, and the effect of inclusions on the corrosion resistance of Q450NQR1 weathering steel was only reflected in the initial stages of corrosion. The inclusions of CaS in Ca-modified test steel and RE oxides and sulfides in RE-modified test steel were preferentially dissolved in acid media, slowing down the corrosion rate of steel matrix, but the non-metallic inclusion Al2O3 may accelerate the corrosion rate of the steel matrix as a form of differential aeration corrosion. Originality/value The effects of inclusions on corrosion resistance of Q450NQR1 weathering steel was investigated by dry–wet cycle immersion test and FE-SEM. The effect of inclusions on the corrosion resistance of Q450NQR1weathering steel was only reflected in the initial stages of corrosion. The inclusions of CaS in Ca-modified test steel and rare earth (RE) oxides and sulfides in RE-modified test steel were preferentially dissolved in acid media, slowing down the corrosion rate of steel matrix, but the non-metallic inclusion Al2O3 may accelerate corrosion rate of the steel matrix as a form of differential aeration corrosion.
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Habibullah, Pervaiz. "Identification of Defects of Stainless Steel Sold with Brand Names, by Studying their Surface Thin Films with Scanning Electron Microscope (SEM)." Key Engineering Materials 622-623 (September 2014): 53–63. http://dx.doi.org/10.4028/www.scientific.net/kem.622-623.53.
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In the present paper, we have studied the thin films formed on the commercial stainless steel sold under different brand names in Pakistan with the help of SEM, EDX and XRD and have further investigated that how such stainless steels lose their brightness and become dull. A sample of recycled stainless steel melted in induction furnace was taken for study. The analysis of the layer formed is as follows: wt. %, C = 6.55, O = 6.20, Na = 0.47, Mg = 0.31, Al = 2.28, Si = 1.23, Cr = 15.42, Mn = 1.06, Fe = 59.58, Ni = 6.91 Total = 100, Atomic %, C = 21.02 O = 14.93, Na = 0.79, Mg = 0.49, Al = 3.26, Si = 1.68, Cr = 11.43, Mn = 0.74, Fe = 41.12, Ni = 4.53. Stainless steel has austenite structure, is non magnetic and forms fine passive film of Cr (III) oxide, (Cr2O3) which prevents surface corrosion and avoids further corrosion from spreading in metal’s internal structure. Mn and Ni stabilize austenite structure. XRD spectra show presence of αFe2O3 and Cr2O3 and spinal oxides in the film formed on the sample taken for study. SEM images show how this thin film tears. In a sound stainless steel, the film formed is too thin to be visible and metal remains lustrous. The film quickly reforms when surface is scratched (passivation). Mostly stainless steel is recycled and average stainless steel objects manufactured and marketed are composed of above 60% recycled material. Oxide spinals of Mn, Ni, Cr with iron oxide are not very resistive to the corrosion. Recently Duplex stainless steel has been manufactured which contains 50:50 austenite and ferrite and have twice the strength compared to austenite stainless steel. Keywords Recycle stainless steel, composition of thin film with EDX, SEM images, investigation on αFe2O3 and Cr2O3 spinals. In the present paper, we have studied the thin films formed on the commercial stainless steel sold under different brand names in Pakistan* with the help of SEM, EDX and XRD and have further investigated that how such stainless steels lose their brightness and become dull. The sample is austenitic stainless steel.
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Craddock, Paul T. "The Many and Various Roles of Manganese in Iron and Steel Production." Materials Science Forum 983 (March 2020): 57–63. http://dx.doi.org/10.4028/www.scientific.net/msf.983.57.
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Manganese oxide and metallic manganese have made a long and varied contribution to the production of iron and steel through the centuries, long before Sir Robert Hadfield’s alloy manganese steel first produced in 1882. Although quite well known empirically, this contribution has sometimes been misunderstood or misrepresented.The success of some of the early so-called ‘natural steels’ was the presence of manganese oxides in the iron ores used.Manganese oxide was already used as a flux from the early days of the production of crucible steel in Asia and it now appears that it was used as a flux from the inception of the otherwise very different later European crucible steel technologies. After the introduction of crucible steel making in Britain in the 18th century, foreign competitors believed that the reason for the success of the processes used at Sheffield was a secret flux and studies on recently discovered 18th century crucibles in Sheffield have shown that process was indeed fluxed with manganese oxide.The function of manganese in the later European crucible steel industry has been rather overshadowed and confused historically by the very different ‘Carburet of manganese’, a strange concoction, patented by Josiah Heath in 1839 added to iron or steel to purify the metal. At the time the chemistry of the process was misunderstood and many acrimonious and inaccurate claims were made, crucially confusing the very different functions of manganese oxide and manganese metal, overshadowing the part already played by manganese oxide for almost a century previously..Finally manganese and its salts played a crucial role in the Bessemer process of steel making.
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Sunil Kumar, B., Vivekanand Kain, K. Benerjee, P. D. Maniyar, S. Sridhar, Kumar Jitendra, and Kumar Jatin. "Effect of Oxidation on Corrosion Behavior of Austenitic Stainless Steel 304L Welds." Advanced Materials Research 794 (September 2013): 598–605. http://dx.doi.org/10.4028/www.scientific.net/amr.794.598.
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The in-cell stainless steel piping and erection works require extensive welding. In many instances the approach for gas tungsten arc welding (GTAW) is limited and it is not possible to provide a cover of high purity inert Argon gas (backing shield) and in some instances, oxidation of the weldment takes place. The oxide forms over the weld fusion zone (root pass) as well as a heat tint forms over the surfaces of the adjacent base material. In reprocessing and waste management plants, the welded pipes come in contact with the process fluid which is nitric acid of concentration up to 6 M and at temperatures up to boiling point. The present study was focused on preparing induced oxidized welds of type 304L using filler wire of type 308L, using gas tungsten arc welding (GTAW) process and studying their corrosion behavior in nitric acid environments. Sample welds were prepared under proper welding conditions and also with conditions in which deliberately Argon gas was not purged or partially purged. The weldments with no oxides, partial oxides and excess oxides on the weld root pass were used for corrosion and characterization studies. Micro Laser Raman spectroscopy established the oxide to be hematite. Metallographic examination of the cross-section of the weldment showed the thickness of oxide to be 200-300 mm. Corrosion tests of the weldments as per practice C, A262, ASTM were done for five periods. Metallographic examination was done after the practice C exposures and showed absence of oxides on the weld root pass. Type 304L specimens were heat treated at 500 – 900 °C for 5 minutes to generate heat tints. These specimens were tested as per practice C, A262, ASTM for 5h and four periods of 48 h each. The corrosion rate in the first five hours exposure was high for the specimen heat treated at 900 °C but it came down to normal values in subsequent exposures. To confirm the corrosion behavior of hematite and magnetite in boiling nitric acid, powders of pure Fe2O3 and Fe3O4 were tested in boiling 65% nitric acid. The results are analyzed to establish the behavior of oxides on the stainless steel welds in nitric acid.
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Deng, Hongda, Yongliang Liu, Zhen He, Xiantao Gou, Yefan Sheng, Long Chen, and Jianbing Ren. "Electrochemical corrosion resistance of thermal oxide formed on anodized stainless steel." Anti-Corrosion Methods and Materials 68, no. 2 (April 9, 2021): 105–12. http://dx.doi.org/10.1108/acmm-10-2020-2385.
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Purpose The purpose of this paper is to investigate and explain thermal oxide effect on electrochemical corrosion resistance anodized stainless steel (SS). Design/methodology/approach Electrochemical corrosion resistance of thermal oxides produced on anodized 304 SS in air at 350°C, 550°C, 750°C and 950°C in 3.5 wt.% NaCl solution have been investigated by dynamic potential polarization, EIS and double-loop dynamic polarization. Anodized 304 SS were obtained by anodization at the constant density of 1.4 mA.cm-2 in the solution containing 28.0 g.L-1H3PO4, 20.0 g.L-1C6H8O7, 200.0 g.L-1H2O2 at 70°C for 50 min. SEM and EDS had been also used to characterize the thermal oxides and passive oxide. Findings Interestingly, anodized 304SS with thermal oxide produced at 350°C displayed more electrochemical corrosion and pitting resistance than anodized 304 SS only with passive oxide, as related to the formation of oxide film with higher chromium to iron ratio. Whereas, anodized 304SS with thermal oxide formed at 950°C shows the worse electrochemical corrosion and pitting resistance among those formed at the high temperatures due to thermal oxide with least compact. Originality/value When thermally oxidized in the range of 350°C–950°C, electrochemical corrosion and pitting corrosion resistance of anodized 304 SS decrease with the increase of temperature due to less compactness, more defects of thermal oxide.
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Grigor’ev, A. М., K. V. Grigorovich, А. Yu Em, and A. O. Morozov. "Interaction of rail steel melt with refractory lining." Izvestiya. Ferrous Metallurgy 64, no. 7 (August 28, 2021): 484–87. http://dx.doi.org/10.17073/0368-0797-2021-7-484-487.
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The rail steel properties are adversely affected by rigid non-metallic inclusions, containing aluminum oxides. Therefore, aluminum content is limited to 0.004 % wt. in rail steel grades. Aluminum can get into steel from charge materials and refractory lining. In this work, we’ve analyzed how the chemical composition of refractories used in rail steel making influence steel quality on example of one domestic enterprise. To determine the main types of non-metallic inclusions created in E76F rail steels, we have performed fractional gas analysis of the samples taken in various process steps. It was found that the slag composition after degassing changes insignificantly, while the most part of non-metallic inclusions in rail steel is represented by aluminates.
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Zou, Jingjing, Hangyu Zhu, Jian Sun, Jigang Liu, and Jixuan Zhao. "A study on direct alloying with molybdenum oxides by feed wire method." Metallurgical and Materials Engineering 24, no. 1 (April 2, 2018): 17–25. http://dx.doi.org/10.30544/346.
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Direct alloying with molybdenum oxides has been regarded in years; the main addition methods are adding to the bottom of electric arc furnace (EAF) with scrap, adding to the ladle during the converter tapping and mixing molybdenum oxide, lime and reductant to prepare pellet added to basic oxygen furnace (BOF). In this paper, a new method for direct alloying with molybdenum trioxide is proposed, adding molybdenum trioxide molten steel by feeding wire method in ladle furnace (LF) refining process. The feasibility of molybdenum oxide reduction, the influence rules of bottom-blown on liquid steel fluidity and the yield of molybdenum by feeding wire method were analyzed. Results show that molybdenum oxide can be reduced by [Al], [Si], [C], and even [Fe] in molten steel. Bottom blowing position has a significant influence on the flow of molten steel when the permeable brick is located in 1/2 radius. The yields of Mo are higher than 97% for the experiments with feed wire method, the implementation of direct alloying with molybdenum trioxide by feed wire method works even better than that uses of ferromolybdenum in the traditional process.
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Feng, Ying-ying, Huan Yu, Zong-an Luo, Guang-ming Xie, and R. Misra. "The Impact of Surface Treatment and Degree of Vacuum on the Interface and Mechanical Properties of Stainless Steel Clad Plate." Materials 11, no. 9 (August 21, 2018): 1489. http://dx.doi.org/10.3390/ma11091489.
Full textAbstract:
In this study, the impact of different surface treatment and degree of vacuum on the interface and mechanical properties of 304/Q345 stainless steel clad plate was investigated. The study indicated that more continuous or aggregated Al2O3 and Si-Mn composite oxides were formed at the interface after brush grinding. However, less inclusions such as Al2O3, MnS and Ca-Mg-Al-Si composite oxides were formed at the interface after pickling treatment. For the vacuum degrees of 10−2 Pa, 1 Pa and 105 Pa, the oxidation reaction became more intense with the decrease in vacuum degree. The interface inclusions were gradually changed from Al2O3 and Si-Mn complex oxides to oxide scale and MnCr2O4 spinel oxide. The interfacial bonding strength of stainless steel clad plate was improved with the increase in degree of vacuum. The bonding strength was 55 MPa at vacuum of 105 Pa, but it was 484 MPa at vacuum of 10−2 Pa, which is far greater than that of the national standard, and an excellent performance was obtained.
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Oshima, Takayuki, Yutaka Yamaguchi, and Kotaro Kuroda. "Microstructural Characterization of Oxide Scale Formed by Early Stage of Oxidation of 17%Cr-Mn-Ni Austenitic Stainless Steel." Materials Science Forum 561-565 (October 2007): 99–102. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.99.
Full textAbstract:
The microstructure of oxide scale formed in the early stage of oxidation of cold-rolled sheets of 17%Cr-Mn-Ni austenitic stainless steel was examined using SEM and TEM. Samples were oxidized at 973 to1373K for 1 to 15min. Nodules were observed on the surfaces of specimens oxidized at 1173K. The nodules were composed of two layers, which comprised Fe oxides and Cr-rich Fe-Cr-Mn oxides, respectively. The other scale was composed of two layers of Fe-Cr-Mn oxides with different compositions. Nodules were not observed on the surfaces of the specimens oxidized at 973 and 1373K. After oxidation at 1373K for 1min, the scale was composed of three layers. The first layer consisted of Fe-Mn oxides with a spinel structure, the second consisted mainly of Cr oxides, and the third consisted of Cr-Mn oxides containing a small amount of Fe.