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A new step-cooling process for strength and toughness matching control of vanadium-containing railway wheels:effect of intragranular ferrite
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作者 YAO Sancheng LIU Xuehua +3 位作者 ZHAO Hai JIANG Bo CHEN Gang XU Kang 《Baosteel Technical Research》 CAS 2023年第3期40-48,共9页
To improve the competitive relationship between strength and toughness,the effect of low undercooling in austenite(γ)on the microstructure and mechanical properties of commercial vanadium-containing wheel steels was ... To improve the competitive relationship between strength and toughness,the effect of low undercooling in austenite(γ)on the microstructure and mechanical properties of commercial vanadium-containing wheel steels was studied using an optical microscope(OM),a scanning electron microscope(SEM),a transmission electron microscope(TEM),and mechanical property tests.The results show that when the wheel steel is slightly cooled to an appropriate temperature above A c3 point for a short time after it has been austenitized at an elevated temperature,the solid-solved vanadium is pre-precipitated in the form of V(C,N)second phase semicoherent with the matrix in the originalγgrain.This phase hardly participates in matrix strengthening.Due to the small mismatch between V(C,N)and ferrite(α),during the subsequent-cooling phase transformation stage,the pre-precipitated second phase becomes theαnucleation point,causing granular and ellipsoidal intragranular ferrite(IGF,with an average size of 4-6μm)to nucleate in the originalγ.The IGF production and strength loss increases with the increasing undercooling degree.Based on this,Masteel Co.,Ltd.has developed a new heat-treatment step-cooling process that can promote the formation of IGF,considerably improving the level and uniformity of fracture toughness on the premise that the strength and hardness of the wheel are almost unchanged. 展开更多
关键词 vanadium microalloyed railway wheel strength and toughness match low undercooling in austenite intragranular ferrite second phase step-cooling process
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Influence of Asymmetric Monotonic Hot Rolling on Microstructures and Mechanical Property of Microalloyed Steel
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作者 李建平 刘珍光 +1 位作者 BAI Xiaolei LI Ping 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第2期422-429,共8页
For refining grain and obtaining excellent properties, the experiments of asymmetric and symmetric monotonic hot rolling were carried out to investigate the role of shear strain on the microstructures and mechanical p... For refining grain and obtaining excellent properties, the experiments of asymmetric and symmetric monotonic hot rolling were carried out to investigate the role of shear strain on the microstructures and mechanical properties of V-microalloyed steel. The study demonstrates that the gradient ferrite distribution and dispersive pearlite through the sheet thickness are observed in asymmetric rolled specimen, and the homogeneous microstructure with ferrite and large pearlite is found in symmetric rolled specimen. The average grain size in asymmetric rolled specimen is smaller than the one in symmetric rolled specimen. The styles of precipitate morphology in asymmetric rolled specimen are random precipitate and obvious interphase precipitate, while the ones in symmetric rolled specimen are random precipitate and unobvious interphase precipitate. The additional shear strain results in the microstructure difference between asymmetric rolled specimen and symmetric rolled specimen. The impact energy of asymmetric rolled specimen, 58 J, is more than the one of symmetric rolled specimen, 48 J. Both deflection-energy curve and fracture morphology show that the fracture style of asymmetric rolled specimen is ductile, and the ones of symmetric rolled specimen are brittle and ductile. 展开更多
关键词 asymmetric rolling microstructure shear strain vanadium microalloyed steel
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Effect of Vanadium Microalloying on the HAZ Microstructure and Properties of Low Carbon Steels 被引量:3
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作者 Milbourn D Baker T N 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第S1期393-403,共11页
Four Steels,C-Mn-0.05V,C-Mn-0.11V,C-Mn-0.03Nb and C-Mn were subjected to heat treatment to simulate the microstructure of a coarse grained heat affected zone (CGHAZ) and an intercritically reheated coarse grained heat... Four Steels,C-Mn-0.05V,C-Mn-0.11V,C-Mn-0.03Nb and C-Mn were subjected to heat treatment to simulate the microstructure of a coarse grained heat affected zone (CGHAZ) and an intercritically reheated coarse grained heat affected zone (ICCGHAZ).This involved reheating to 1350°C,rapid cooling (Δt 8/5 =24s) to room temperature and then reheating to either 750°C or 800°C.The toughness of the HAZs was assessed using both Charpy and CTOD tests.Microstructural features were characterised by optical,scanning` and transmission electron microscopy.Fractographic examinations of the Charpy and CTOD specimens were carried out to understand the micromechanism of fracture under different microstructural and test conditions.The CGHAZ toughness was similar for the steels except that Steel C-Mn-0.05V had a slightly lower ITT compared to the others.The toughness deteriorated in the ICCGHAZ for all the steels,again Steel C-Mn-0.05V had a superior toughness compared to the other three steels in both ICCGHAZ conditions.Raising the level of vanadium to 0.11% caused a decrease in ICCGHAZ toughness.Steel C-Mn-Nb exhibited a greater degradation of impact toughness after the intercritical cycles.The presence of M-A constituents was the dominant factor in determining the toughness of the ICCGHAZs.The size and area fraction of the M-A constituents were the smallest in Steel C-Mn-0.05V.Increasing vanadium level to 0.11% resulted in a greater area fraction of the M-A constituents,larger average and maximum sizes of M-A particles,and significantly more fields containing the M-A.The addition of 0.031% Nb produced the largest M-A particles and the greatest area fraction for the steels tested. 展开更多
关键词 vanadium microalloyed steel coarse grained heat affected zone intercritically reheated coarse grained heat affected zone martensite-austenite constitute heat affect zone toughness
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Effect of Carbon on Dynamic Recrystallization Behavior of Vanadium Microalloy Steels 被引量:1
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作者 LIU Guo-quan 1,2,ZHAO Hai-tao 1,WU Jin-bin 1,WANG Cheng-yang 1,XU Lei 1,3 (1.School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China 2.State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China 3.Department of Materials Science and Engineering,Tsinghua University,Beijing 100084,China) 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第S1期129-134,共6页
The hot working behavior especially dynamic recrystallization of low-carbon and medium-carbon vanadium microalloy steels has been studied by performing isothermally compression tests and Avrami analysis.The Avrami plo... The hot working behavior especially dynamic recrystallization of low-carbon and medium-carbon vanadium microalloy steels has been studied by performing isothermally compression tests and Avrami analysis.The Avrami plots of the two experiment steels have been constructed based on flow stress curves following a new approach (Jonas,et al.Acta Mater.,2009,57(2):2748-2756;Wu et al,Acta Metall.Sin.,2010,46(7):838-843).It is experimentally found that the carbon effect on dynamic recrystallization is opposite to each other in lower and higher strain ranges:Carbon causes a softening effect at low strain rates (0.01,0.1,and 1.0 s-1),and a hardening effect at high strain rates (10.0 and 30.0 s-1).Correspondingly,carbon promotes the dynamic recrystallization at low strain rates and retards the dynamic recrystallization at high strain rates in the experimental steels.The phenomenon is then tentatively explained based on the possible mechanisms of dynamic process at different strain rates. 展开更多
关键词 vanadium microalloy steels hot working dynamic recrystallization CARBON strain rate Avrami modeling
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Grain Growth of Deformation Induced Ferrite in V Microalloyed Low Carbon Steel During Controlled Cooling Process 被引量:1
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作者 WANG Kai 1,WANG Li-jun 2,WANG Qiang 1,HE Ji-cheng 1,LIU Chun-ming 2 (1.Key Laboratory of Electromagnetic Processing of Materials,Ministry of Education,Northeastern University,Shenyang 110819,China 2.School of Materials and Metallurgy,Northeastern University,Shenyang 110819,China) 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第S1期377-382,共6页
The effect of vanadium on the DIFT (Deformation Induced Ferrite Transformation) microstructure coarsening in low carbon steel during the continuous cooling processes and isothermal processes at different temperatures ... The effect of vanadium on the DIFT (Deformation Induced Ferrite Transformation) microstructure coarsening in low carbon steel during the continuous cooling processes and isothermal processes at different temperatures were investigated using thermo-simulator.The results showed that the steel containing a small amount of vanadium had the similar velocity of grain growth with the vanadium free steel during the continuous cooling process,but a lower velocity of grain growth than that of vanadium free steel during isothermal processes at high temperatures.On the other hand,the vanadium remarkably inhibited grain growth in the steel containing a high amount of vanadium during both the continuous cooling and isothermal processes.Vanadium dissolved in matrix is indicated as an important factor on restraining grain growth through estimating the driving force of normal grain growth and the resistance of precipitation particles of vanadium on grain growth.The influencing mechanism of vanadium dissolved in matrix on the grain growth during the controlled cooling process is discussed. 展开更多
关键词 low carbon steel vanadium microalloying DIFT grain growth controlled cooling process
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Effect of Cooling Rate and Vanadium Content on the Microstructure and Hardness of Medium Carbon Forging Steel 被引量:7
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作者 Weijun Hui Yongjian Zhang +3 位作者 Chengwei Shao Silian Chen Xiaoli Zhao Han Dong 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2016年第6期545-551,共7页
This paper reports the effect of cooling rate on the microstructure and hardness of a kind of medium carbon steel microalloyed with two levels of V content (0.15% and 0.28%) after hot deformation by using single com... This paper reports the effect of cooling rate on the microstructure and hardness of a kind of medium carbon steel microalloyed with two levels of V content (0.15% and 0.28%) after hot deformation by using single compression tests on a Gleeble-3800 thermal simulator. The results show that cooling rate has a significant effect on the microstructure and hardness of the tested steels. Both the fraction of pearlite and hardness increase with increasing cooling rate, whereas a further increase of the cooling rate above a critical value promotes the formation of acicular ferrite (AF), and thus leads to a decrease of hardness mainly owing to the decrease of pearlite fraction and replacing it by AF and the less effective precipita- tion strengthening. Increasing V content results in a significant increase of hardness, and this tendency enhances with increasing cooling rate until the formation of AF. Furthermore, increasing V content also significantly enhances the formation of AF structure at a lower cooling rate. The results also suggest that by controlling microstructure, especially the precipitation of fine V(C,N) particles through adjusting post- forging cooling, the strengthening and gradient function in one hot-forging part could be obtained. 展开更多
关键词 Cooling rate microalloyed steel vanadium Microstructure Hardness Acicular ferrite
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Influence of Vanadium on Fracture Splitting Property of Medium Carbon Steel 被引量:2
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作者 Wei-jun HUI Cheng-wei SHAO +2 位作者 Yong-jian ZHANG Si-lian CHEN Han DONG 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2016年第5期475-483,共9页
The fracture splitting property of medium carbon steel 37MnSiS microalloyed with V up to 0. 45% was investigated by using simulated fracture splitting test,for the development of new crackable medium carbon steel to m... The fracture splitting property of medium carbon steel 37MnSiS microalloyed with V up to 0. 45% was investigated by using simulated fracture splitting test,for the development of new crackable medium carbon steel to manufacture high performance connecting rod. Conventional high carbon steel C70S6 was used for comparison. The results show that the volume fraction of both ferrite and V-rich M( C,N) particles increases,and the pearlite interlamellar spacing decreases with increasing V content,which in turn results in gradual increase of strength and decrease of ductility and impact energy. The fracture splitting property of the tested steel could be improved significantly due to the increase of V content mainly through the precipitation hardening mechanism of fine M( C,N) precipitates. The fraction of brittle cleavage fracture in the crack initiation area increases noticeably with increasing V content and full brittle cleavage fracture surface could be obtained when V content was increased to 0. 45%. It is concluded that medium carbon steel with V content higher than about 0. 28% possesses not only comparable or even higher mechanical properties with those of conventional steel C70S6,but also excellent fracture splitting property,and therefore,is more suitable to fabricate high performance fracture splitting connecting rod. 展开更多
关键词 microalloyed medium carbon steel fracture splitting vanadium precipitation hardening microstructure
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Enhanced strength and toughness of high nitrogen stainless bearing steel by controlling interstitial partitioning via V-microalloying 被引量:1
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作者 Lingfeng Xia Huabing Li +4 位作者 Hao Feng Zhouhua Jiang Hongchun Zhu Shucai Zhang Xiaodong Wang 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2023年第20期204-218,共15页
High-nitrogen stainless bearing steel(HNSBS)with ultra-high tensile strength(∼2403 MPa)and good toughness(∼80.0 J)was obtained by V-microalloying,overcoming the strength-toughness trade-off of conventional V-free HN... High-nitrogen stainless bearing steel(HNSBS)with ultra-high tensile strength(∼2403 MPa)and good toughness(∼80.0 J)was obtained by V-microalloying,overcoming the strength-toughness trade-off of conventional V-free HNSBS.In this work,since V-microalloying facilitated the enrichment of interstitial atoms(C and N)in precipitates,the content of interstitial atoms in the matrix was reduced accordingly(i.e.,interstitial partitioning).On the one hand,V-microalloying reduced the substantial intergranular precipitates and transformed the precipitates from M_(23)C_(6)+M_(2)N into V-containing M_(23)C_(6)+M_(2)N+MN with multi-scale particle sizes,causing a coupling strengthening effect,which contributed to the toughness and additional strength increase.On the other hand,V-microalloying controlled interstitial partitioning,effectively refined coarse retained austenite(RA),increased the fraction of dislocation martensite,and reduced the fraction of twin martensite.The more film-like RA and dislocation martensite with high dislocation density coordinated plastic deformation and prevented crack propagation,thus obviously enhancing the strength and toughness of 0.2 V steel.This study provides a new route to develop high-performance HNSBS for aerospace applications. 展开更多
关键词 High-nitrogen stainless bearing steel vanadium microalloying Interstitial partitioning Strength and toughness
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Warm Forged Medium Carbon V Steel
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作者 Carlos Garcia-Mateo Beatriz Lopez Jose Maria Rodriguez-Ibabe 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第S1期822-826,共5页
Nowadays there is a continuous demand,particularly from the automotive industry,for cheaper,lighter and more reliable components.It is not surprising then that steel research has been focused during the last decades i... Nowadays there is a continuous demand,particularly from the automotive industry,for cheaper,lighter and more reliable components.It is not surprising then that steel research has been focused during the last decades in new qualities and processes.This paper is dealing with the use of vanadium microalloyed steels on one of those new processes,warm forging.For its low precipitation temperature and its recognised ability to strengthen steel microstructures via austenite grain growth control,precipitation hardening and interference of the static recrystallization process,vanadium in microalloyed steels seem to be an appropriate candidate for warm forging. 展开更多
关键词 warm forging vanadium microalloyed steels
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