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RELATIONSHIP BETWEEN RETAINED AUSTENITE AND STRAIN FOR Si-Mn TRIP STEEL 被引量:1
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作者 王四根 王绪 +2 位作者 花礼先 刘仲武 周洪亮 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 1995年第1期10+7-10,共5页
The equation which reflects the relationship between the retained austenite and strain has been proposed and clear TRIP can be obtained while the S value (An index of retained austenite stability) is less than 6.5 for... The equation which reflects the relationship between the retained austenite and strain has been proposed and clear TRIP can be obtained while the S value (An index of retained austenite stability) is less than 6.5 for Silicon-Manganese TRIP steel 展开更多
关键词 transformation induced plasticity (TRIP) retained austenite stability Silicon-Manganese alloys
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EFFECT OF CHEMICAL COMPOSITION ON RETAINED AUSTENITE IN TRIP STEEL 被引量:19
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作者 Y. Chen and X. ChenWuhan University of Science and Technology, Wuhan 430081, ChinaQ.F. Wang, G.L. Yuan and. C. Y. LiTechnical Center of Wuhan Iron and Steel Co., Wuhan 430080, ChinaX. Y. Li and Y.X. WangCentral Iron and Steel Research Institute, Beijing 1 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2002年第4期339-345,共7页
The systematic chemical compositions including common C, Si, Mn, Al, and micro-alloying elements of Ti and Nb were designed for high volume fraction of retained austenite as much as possible. The thermo-cycle experime... The systematic chemical compositions including common C, Si, Mn, Al, and micro-alloying elements of Ti and Nb were designed for high volume fraction of retained austenite as much as possible. The thermo-cycle experiments were conducted by using Gleeble 2000 thermo-dynamic test machine for finding the appropriate composition. The experimental results showed that chemical composition had a significant effect on retained austenite, and the appropriate compositions were determined for commercial production of TRIP steels. 展开更多
关键词 carbon content silicon content manganese content retained austenite TRIP steel
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Effects of Si on the stability of retained austenite and temper embrittlement of ultrahigh strength steels 被引量:9
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作者 Li-jun Wang Qing-wu Cai Hui-bin Wu Wei Yu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2011年第5期543-550,共8页
Effects of silicon (Si) content on the stability of retained austenite and temper embrittlement of ultrahigh strength steels were investigated using X-ray diffraction (XRD),transmission electron microscopy (TEM)... Effects of silicon (Si) content on the stability of retained austenite and temper embrittlement of ultrahigh strength steels were investigated using X-ray diffraction (XRD),transmission electron microscopy (TEM),and other experimental methods.The results show that Si can suppress temper embrittlement,improve temper resistance,and hinder the decomposition of retained austenite.Reversed austenite appears gradually with the increase of Si content during tempering.Si has a significant effect on enhancing carbon (C) partitioning and improving the stability of retained austenite.Si and C atoms are mutually exclusive in lath bainite,while they attract each other in austenite.ε-carbides are found in 1.8wt% Si steel tempered at 250℃,and they get coarsened obviously when tempered at 400℃,leading to temper embrittlement.Not ε-carbides but acicular or lath carbides lead to temper embrittlement in 0.4wt% Si steel,which can be inferred as cementites and composite compounds.Temper embrittlement is closely related to the decomposition of retained austenite and the formation of reversed austenite. 展开更多
关键词 SILICON ultrahigh strength steel retained austenite temper embrittlement reversed austenite
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Effect of lower bainite/martensite/retained austenite triplex microstructure on the mechanical properties of a low-carbon steel with quenching and partitioning process 被引量:4
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作者 Wan-song Li Hong-ye Gao +3 位作者 Zhong-yi Li Hideharu Nakashima Satoshi Hata Wen-huai Tian 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2016年第3期303-313,共11页
We present a study concerning Fe-0. 176C-1.31Si-1.58Mn-0.26Al-0.3Cr (wt%) steel subjected to a quenching and partitioning (Q&P) process. The results of scanning electron microscopy, transmission electron microsco... We present a study concerning Fe-0. 176C-1.31Si-1.58Mn-0.26Al-0.3Cr (wt%) steel subjected to a quenching and partitioning (Q&P) process. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and tensile tests demon- strate that the microstructures primarily consist of lath martensite, retained austenite, lower bainite (LB), and a small amount of tempered martensite; moreover, few twin austenite grains were observed. In the microstrucmre, three types of retained austenite with different sizes and morphologies were observed: blocky retained austenite (-300 nm in width), film-like retained austenite (80-120 nm in width), and ul- tra-fine film-like retained austenite (30-40 nm in width). Because of the effect of the retained austenite/martensite/LB triplex microstructure, the specimens prepared using different quenching temperatures exhibit high ultimate tensile strength and yield strength. Furthermore, the strength effect of LB can partially counteract the decreasing strength effect of martensite. The formation of LB substantially reduces the amount of retained austenite. Analyses of the retained austenite and the amount of blocky retained austenite indicated that the carbon content is critical to the total elongation of Q&P steel. 展开更多
关键词 low-carbon steel QUENCHING partitioning retained austenite rnicrostructure mechanical properties
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EFFECTS OF CARBON CONTENT AND ROLLING PROCESSING ON RETAINED AUSTENITE FOR HOT-ROLLED TRIP STEELS 被引量:5
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作者 Y. Chen, X. Chen, Z.X. Yuan, B.F. Xu, A.M. Guo, P.H. Li and S.K. PuWuhan University of Science and Technology, Wuhan 430081, ChinaTechnical Center of Wuhan Iron and Steel Co., Wuhan 430080, China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2002年第5期439-447,共9页
The effects of finishing rolling temperature and coiling temperature on retained austen-ite were studied for hot-rolled transformation induced plasticity (TRIP) steels with different carbon content. The experimental r... The effects of finishing rolling temperature and coiling temperature on retained austen-ite were studied for hot-rolled transformation induced plasticity (TRIP) steels with different carbon content. The experimental results showed that an appropriate volume fraction of retained austenite from 6% to 11% could be obtained according to the different carbon content less than 0.20% by controlled finishing rolling and coiling for the hot-rolled TRIP steels. It can be concluded that carbon content has a significant effect on the fraction of retained austenite and coiling processing plays stronger role on retaining austenite than fishing rolling processing. 展开更多
关键词 TRIP steel carbon content retained austenite
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Characteristics of Retained Austenite in TRIP Steels with Bainitic Ferrite Matrix 被引量:1
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作者 张明亚 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第6期1148-1151,共4页
Heat treatment process for producing cold rolled transformation induced plasticity-aided (TRIP-aided) steels with bainitic ferrite matrix was adopted. Characteristics of retained austenite (RA) in such TRIP steels... Heat treatment process for producing cold rolled transformation induced plasticity-aided (TRIP-aided) steels with bainitic ferrite matrix was adopted. Characteristics of retained austenite (RA) in such TRIP steels were investigated. SEM and OM determination results showed that the stable austenite retained at room temperature were mainly located between laths and some of them inside the coarse ferrite. The grains were uniformly distributed in heat treated steel matrix and the regularly dispersed RA represented to be triangular morphology. XRD analysis indicated that RA content in matrix was not less than 10%, and TEM testified that RA inside the matrix were formed at the prior austenite boundaries and represented to be single or twin crystals. The ductile fracture originated from the boundaries of martensite islands from RA and ferrite. The cracks propagated along grain boundaries and some passed through the large ferrite grains and induced transgranular fracture. 展开更多
关键词 TRIP steel retained austenite MORPHOLOGY MICROSTRUCTURE
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Effect of retained austenite and nonmetallic inclusions on the thermal/electrical properties and resistance spot welding nuggets of Si-containing TRIP steels 被引量:1
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作者 V.H.Vargas I.Mejía +1 位作者 V.H.Baltazar-Hernández C.Maldonado 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2019年第1期52-63,共12页
Five advanced high-strength transformation-induced plasticity(TRIP) steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical pr... Five advanced high-strength transformation-induced plasticity(TRIP) steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical properties and the characteristics of the resistance spot welding nuggets. Electrical and thermal properties and equilibrium phases of TRIP steels were predicted using the JMatPro? software. Retained austenite and nonmetallic inclusions were quantified by X-ray diffraction and saturation magnetization techniques. The nonmetallic inclusions were characterized by scanning electron microscopy. The results show that the contents of Si, C, Al, and Mn in TRIP steels increase both the retained austenite and the nonmetallic inclusion contents. We found that nonmetallic inclusions affect the thermal and electrical properties of the TRIP steels and that the differences between these properties tend to result in different cooling rates during the welding process. The results are discussed in terms of the electrical and thermal properties determined from the chemical composition and their impact on the resistance spot welding nuggets. 展开更多
关键词 transformation-induced plasticity steel retained austenite non-metallic inclusions magnetic saturation electrical PROPERTIES THERMAL PROPERTIES resistance spot welding NUGGET
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Relations of abrasion resistance and hardness of 16Cr-3C white irons with retained austenite content 被引量:1
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作者 ZhipingSun RulinZuo +3 位作者 CongLi BaoluoShen ShengjiGao SijiuHuang 《Journal of University of Science and Technology Beijing》 CSCD 2004年第6期539-544,共6页
The relationship between the retained austenite content of the matrix in16Cr-3C white irons and the abrasion resistance was investigated. The results show that: (1) theabrasion resistance can be improved by sub-critic... The relationship between the retained austenite content of the matrix in16Cr-3C white irons and the abrasion resistance was investigated. The results show that: (1) theabrasion resistance can be improved by sub-critical heat treatment, which could be attributed to thedecrease of the retained austenite content; (2) both the abrasion resistance and hardness can beimproved by controlling the retained austenite content below 20 percent-30 percent and arrive at themaximum when the retained austenite content is reduced to about 10 percent; (3) the abrasionresistance decreases abruptly once the retained austenite content is lower than 10 percent, whichstems from both the in situ transformation of (Fe, Cr)_(23)C_6 to M_3C carbides and the formation ofpearlitic matrix. 展开更多
关键词 retained austenite abrasion resistance HARDNESS white iron
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EFFECTS OF RETAINED AUSTENITE ON DUPLEX MICROSTRUCTURE OF MARTENSITE AND LOWER BAINITE
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作者 WEN Cui’e LIN Jianguo ZHOU Yajian(Department of Materials Science,Beijing University of Aeronautics and Astronautics,Beijing 100083,China) 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1996年第1期59-64,共6页
The morphology and amount of the retained austenite in the duplex microstructure of martensite and tower bainite of a tow,alloy cold die steel(it is called GD steel for short) with high strength and high toughness hav... The morphology and amount of the retained austenite in the duplex microstructure of martensite and tower bainite of a tow,alloy cold die steel(it is called GD steel for short) with high strength and high toughness have been investigated.The thermal and mechanical stabilities of the retained austenite were analyzed.Furthermore the effects of retained austenite on the mechanical properties of the steel were studied.The results show that the morphology and amount of retained austenite vary with silicon content in the steel.Retained austenite with high stability was responsible for the simultaneous increase in strength and toughness of the steel.The duplex microstructure of martensite and abnormal lower bainite of the steel with the maximum silicon content exhibits a relatively good strength-toughness combination. 展开更多
关键词 MARTENSITE BAINITE die steel retained austenite
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TRIP Steel Retained Austenite Transformation under Cyclic V-bending Deformation
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作者 李洪洋 ZHANG Yanjing +3 位作者 ZHAO Wenjun GU Zhifei LI Xianchao MA Jinlong 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第3期594-600,共7页
To investigate the transformation behavior of TRIP steel retained austenite under cyclic load, cyclic V-bending deformation of low carbon Si-Mn TRIP600 was studied by experiment and finite element in this paper. The r... To investigate the transformation behavior of TRIP steel retained austenite under cyclic load, cyclic V-bending deformation of low carbon Si-Mn TRIP600 was studied by experiment and finite element in this paper. The results showed that, under cyclic V-bending deformation, retained austenite in TRIP steel transformed into martensite gradually with the increasing of bending times, and for the symmetrical characteristic, upper surface and lower surface presented the same transformation tendency. From the first to the fourth V-bending deformatiort, retained austenite volume fraction decreased nearly linearly and then attained saturation step by step. Compressive stress state was helpful for martensite transformation than tension stress state with V-bending deformation, and strain magnitude was the determining factor for retaining anstenite martensitic transformation. With the increasing of bending times effective stress increased and the relationship between maximum effective stress and bending times was nearly linear. Effective stress and effective strain distribution were non-uniform, the maximum effective stress and effective strain were present in the center of the samples. The relationships between retained austenite and V-bending times, and retained austenite with effective strain were set up as Eqs.(1)-(5). The relationship was typical quadric function, decreased linearly for the initial deformation and attained saturation finally. 展开更多
关键词 TRIP steel martensitic transformation retained austenite cyclic load
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RETAINED AUSTENITE IN LASER PROCESSED STEELS
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作者 S. Fedosov (Samara State Technical University, Galaktionovskaya 141, Samara 443010, Russia) 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2000年第1期40-44,共5页
This paper Presents experimental data on effect of carbon concentration and laser processing regimes on retained austenite quantity. The data on retained austenite decomposition during subsequent temperings at vario... This paper Presents experimental data on effect of carbon concentration and laser processing regimes on retained austenite quantity. The data on retained austenite decomposition during subsequent temperings at various temperatures as well as after holding at room temperature during 3 years are given.Correla- tion between structural broadening of the X - ray lines of retained gamma - phase and the amount of the latter has been discovered.Mechanisms responsible for the increased quantity of the retained austen- ite in carbon and low alloyed steels after laser hardening are described. 展开更多
关键词 retained austenite laser hardening laser heat treatment laser processing
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Interaction of Hydrogen and Retained Austenite in Bainite/Martensite Dual-Phase High Strength Steel
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作者 GUJia-lin CHANGKai-di +2 位作者 FANGHong-sheng YANGZhi-gang BAIBing-zhe 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2004年第1期42-46,共5页
The hydrogen trapping phenomena in two bainite/martensite dual-phase high strength steels(U20Si and U20DSi)were investigated by electrochemical permeation technique.The hydrogen diffusivity was calculated from data of... The hydrogen trapping phenomena in two bainite/martensite dual-phase high strength steels(U20Si and U20DSi)were investigated by electrochemical permeation technique.The hydrogen diffusivity was calculated from data of permeation delay time,and the diffusion coefficient in U20 Si is far less than that in U20 DSi.Moreover,the hydrogen diffusivity decreases as the volume percent of retained austenite increases.The experiment results show that there are different hydrogen trappings and different volume percents of retained austenite in U20 Si and U20 DSi.The retained austenite is precipitated as films.The trap binding energy for the retained austenite and hydrogen is calculated to be 40.4kJ·mol-1. 展开更多
关键词 BAINITE martensite dual-phase high strength steel electrochemical permeation technique diffusion coefficient retained austenite trap binding energy
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Quantitative Mossbauer Study on Retained Austenite and Carbide in High Speed Steel
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作者 张恒华 马如璋 +3 位作者 苏世漳 常汝琴 金慧娟 许桂琴 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1992年第4期284-288,共5页
The retained austenite in high speed steel of two different heat treatment regimes was quantitatively,determined by transmission Mssbauer spectroscopy (TMS),backscattering X-ray geometry,Mossbauer spectroscopy (BXMS) ... The retained austenite in high speed steel of two different heat treatment regimes was quantitatively,determined by transmission Mssbauer spectroscopy (TMS),backscattering X-ray geometry,Mossbauer spectroscopy (BXMS) and X-ray diffraction technique.The results meas- ured by these methods were in agreement with each other.It was demonstrated that the concentration of carbides in high speed steel could be measured by transmission Mossbauer spectroscopy or Mossbau- er spectroscopy in backscattering X-ray geometry accurately. 展开更多
关键词 Mssbauer spectroscopy retained austenite high speed steel
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TRANSFORMATION OF RETAINED AUSTENITE IN CARBURIZED CASE DURING FATIGUE CRACK GROWTH
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作者 JING Xiaotian LOU Bingzhe GU Chenqing SHEN Fusan Shanxi Institute of Mechanical Engineering,Xi’an,China Dept.of Materials,Shanxi Institute of Mechanical Engineering,Xi’an 710048,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1990年第4期268-275,共8页
The morphology of the retained austenite in the carburized case of 20CrNiMo steel and its transformation during fatigue crack propagation through the case were investigated by using X-ray and TEM analysis.In the carbu... The morphology of the retained austenite in the carburized case of 20CrNiMo steel and its transformation during fatigue crack propagation through the case were investigated by using X-ray and TEM analysis.In the carburized case both film and block shaped retained austenite were found.Due to the crystallographic orientation relationship at the interface,the fatigue crack is inclined to pass through the block shaped retained austenite and thereby stim- ulates its strain-induced martensitie transformation.During the process of the fatigue frac- ture,most of the retained austenite structures on the crack path are transformed into the martensite,and the untranaformed parts on the fracture surface remain less than 6%.The transformation of the retained austenite,which is restrieted mainly within the plastic zone,oc- curs only during the proeess of fracture,and is independent of the magnitudes of the external stress,stress ratio and cyclic number.The volume expansion accompanying the transforma- tion creates an additional residual displacement of about 0.44μm on fracture surfaces,which is equivalent to the magnitude of the plasticity-induced residual displacement.The phase transformation induced fatigue crack closure is believed to be an important factor affecting the fatigue crack behaviors in the high carbon laver of the carburized case. 展开更多
关键词 retained austenite fatigue crack growth strain induced martensitic trarsformation phase transformation induced crack closure
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Physical Simulation of Thermally Induced Martensite Formation from Retained Austenite in TRIP Steels
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作者 Lie ZHAO Fred J. VERMOLEN Jilt SIETSMA Sybrand van der ZWAAG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2003年第z1期105-108,共4页
The present work analyses the total free energy of the material during the martensitic transformation. A general expression for the martensite fraction as a function of temperature is derived, assuming that the nonche... The present work analyses the total free energy of the material during the martensitic transformation. A general expression for the martensite fraction as a function of temperature is derived, assuming that the nonchemical free energyis proportional to the volume of martensite. This expression indicates that the temperature-dependent martensitefraction can be predicted once the characteristic transformation temperatures and the relation between the chemicalfree energy and temperature of the martensite and austenite are known. An advantage of this development is thatthe proposed equation is valid for all types of relations between the chemical free energy and temperature. Thissimulation is successfully applied to the martensitic transformation upon further cooling of retained austenite in alow-alloyed TRIP steel, in which the relation between chemical free energy and temperature is quadratic and thefraction is determined from a thermo-magnetic measurement. 展开更多
关键词 Thermodynamics Martensitic transformation retained austenite TRIP steels.
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A novel design to enhance the stability of local austenite and the volume fraction of retained austenite in a low-carbon Si Mn Q-P steel
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作者 ZHANG Jun YAO Liandeng 《Baosteel Technical Research》 CAS 2022年第1期24-29,共6页
Pre-quenching prior to intercritical annealing quenching and partitioning(Q-P)process was proposed to enhance the volume fraction of retained austenite and the mechanical properties of a low-carbon Si Mn steel.The int... Pre-quenching prior to intercritical annealing quenching and partitioning(Q-P)process was proposed to enhance the volume fraction of retained austenite and the mechanical properties of a low-carbon Si Mn steel.The intercritical austenite exhibited a lath morphology due to the martensitic microstructure maintained prior to intercritical annealing.Consequently,the alloy element enrichment of intercritical austenite,in which the alloy element was aggregated at the austenitic boundaries and further diffused inside,improved the stability of intercritical austenite and decreased the M_(s) of it.As a result,the fraction of retained austenite in steel was increased,which improved the mechanical properties of the experimental Q-P steel. 展开更多
关键词 pre-quenching and quenching and partitioning intercritical annealing lath intercritical austenite retained austenite mechanical properties
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Role of retained austenite in advanced high-strength steel:ductility and toughness
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作者 Vung Lam Nuam Hao Zhang +1 位作者 Ying-chun Wang Zhi-ping Xiong 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2024年第9期2079-2089,共11页
Enhancing the ductility and toughness of advanced high-strength steels is essential for the wide range of promising applications.The retained austenite(RA)is a key phase due to the austenite-to-martensite transformati... Enhancing the ductility and toughness of advanced high-strength steels is essential for the wide range of promising applications.The retained austenite(RA)is a key phase due to the austenite-to-martensite transformation and its transformation-induced plasticity effect.It is commonly accepted that slow RA-to-martensite transformation is beneficial to ductility;therefore,the RA fraction and stability should be carefully controlled.The RA stability is related to its morphology,size,carbon content,neighboring phase and orientation.Importantly,these factors are cross-influenced.It is noteworthy that the influence of RA on ductility and fracture toughness is not consistent because of their difference in stress state.There is no clear relationship between fracture toughness and tensile properties.Thus,it is important to understand the role of RA in toughness.The toughness is enhanced during the RA-to-martensite transformation,while the fracture toughness is decreased due to the formation of fresh and brittle martensite.As a result,the findings regarding to the effect of RA on fracture toughness are conflicting.Further investigations should be conducted in order to fully understand the effects of RA on ductility and fracture toughness,which can optimize the combination of ductility and toughness in AHSSs. 展开更多
关键词 retained austenite DUCTILITY TOUGHNESS TRIP effect STEEL
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High-temperature stability of retained austenite and plastic deformation mechanism of ultra-fine bainitic steel isothermally treated below Ms
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作者 Ting-ting He Feng Hu +4 位作者 Kun Wang Wen Zhou Li Li Serhii Yershov Kai-ming Wu 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2024年第8期2014-2030,共17页
The mechanical properties of the sample and the stability of retained austenite were studied by designing two kinds of ultra-fine bainitic steel with different heat treatment methods austempering above and below Ms(ma... The mechanical properties of the sample and the stability of retained austenite were studied by designing two kinds of ultra-fine bainitic steel with different heat treatment methods austempering above and below Ms(martensite start tem-perature),which were subjected to tensile tests at 20 and 450℃,respectively.The results show that compared to room temperature(20℃)tensile properties,the uniform elongation of the sample at high temperature(450℃)significantly decreased.Specifically,the uniform elongation of the sample austempered above Ms decreased from 8.0%to 3.5%,and the sample austempered below Ms decreased from 10.9%to 3.1%.Additionally,the tensile strength of the sample austempered above Ms significantly decreased(from 1281 to 912 MPa),and the sample austempered below Ms slightly decreased(from 1010 to 974 MPa).This was due to the high carbon content(1.60 wt.%),high mechanical stability,low thermal stability for the retained austenite of the sample austempered below Ms.Besides,the retained austenite decomposed at high temper-atures,the carbon content and transformation driving force were significantly reduced,the transformation rate increased,and the phase transformation content reduced. 展开更多
关键词 Ultra-fine bainite Isothermal treatment High-temperature tensile property retained austenite stability Plastic deformation
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Machine learning for prediction of retained austenite fraction and optimization of processing in quenched and partitioned steels
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作者 Shuai Wang Jie Li +3 位作者 Li-yang Zeng Xun-wei Zuo Nai-lu Chen Yong-hua Rong 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2024年第8期2002-2013,共12页
The metastable retained austenite(RA)plays a significant role in the excellent mechanical performance of quenching and partitioning(Q&P)steels,while the volume fraction of RA(V_(RA))is challengeable to directly pr... The metastable retained austenite(RA)plays a significant role in the excellent mechanical performance of quenching and partitioning(Q&P)steels,while the volume fraction of RA(V_(RA))is challengeable to directly predict due to the complicated relationships between the chemical composition and process(like quenching temperature(Qr)).A Gaussian process regression model in machine learning was developed to predict V_(RA),and the model accuracy was further improved by introducing a metallurgical parameter of martensite fraction(fo)to accurately predict V_(RA) in Q&P steels.The developed machine learning model combined with Bayesian global optimization can serve as another selection strategy for the quenching temperature,and this strategy is very effcient as it found the"optimum"Qr with the maximum V_(RA) using only seven consecutive iterations.The benchmark experiment also reveals that the developed machine learning model predicts V_(RA) more accurately than the popular constrained carbon equilibrium thermodynamic model,even better than a thermo-kinetic quenching-partitioning-tempering-local equilibrium model. 展开更多
关键词 Q&P steel retained austenite fraction Machine learning Quenching temperature Gaussian process regression model
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Effect of retained austenite on the fracture behavior of a novel press-hardened steel 被引量:3
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作者 Zhisong Chai Qi Lu +4 位作者 Jun Hu Lingyu Wang Zhou Wang Jianfeng Wang Wei Xu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2023年第4期34-45,共12页
Tensile and bending properties are two critical attributes of press hardened steels(PHSs)for automotive body structural components.However,the research on these properties of PHSs with retained austenite(RA),which is ... Tensile and bending properties are two critical attributes of press hardened steels(PHSs)for automotive body structural components.However,the research on these properties of PHSs with retained austenite(RA),which is introduced to improve the mechanical properties,has not been well reported.In this study,the effect of RA on the quasi-static uniaxial tensile and three-point bending behaviors has been systematically investigated for a newly developed Cr and Si alloyed PHS.RA with various degrees of mechanical stabilities was obtained by tuning the auto-tempering of martensite through the control of the die contact pressure during the press hardening process.Mechanically stable RA provides the optimal combination of tensile and bending performance,while the PHS with RA of poor mechanical stability has a deteriorated bending toughness as manifested by a reduction of bending angle from approximately 61.6°to56.8°.However,itstensileproperties,incontrast,arethebestintermsof theproductofulti-mate tensile strength and total elongation(15.9 GPa%).This is mainly attributed to the unstable RA on the outermost surface of the bending sample.The unstable RA can easily transform into brittle martensite under local plane strain and strain gradient conditions in the bending test compared with uniaxial stress in the tensile test,promoting crack initiation and propagation.Furthermore,the effect of martensitic auto-tempering or contact pressure on the quantity and stability of RA are also discussed.This study would provide a useful reference to guide hot stamping process optimization for the newly developed Cr and Si-containing press-hardened steel. 展开更多
关键词 Press-hardened steel retained austenite Tensile property Bending toughness Crack initiation
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