摘要
研究了Nb、V微合金化对正火态、淬火态和回火态Q355B钢微观组织与力学性能的影响。结果表明,Nb、V微合金化后,试验钢奥氏体晶界处存在未完全溶解的球状MC碳化物,这些碳化物钉扎奥氏体晶界,阻碍高温下奥氏体晶界的运动,有效地细化了900℃正火和900℃淬火态试验钢的原始奥氏体晶粒。另外,Nb、V微合金化增加了淬火态试验钢中马氏体的比例,提高了淬透性。经900℃淬火和450~530℃回火后,试验钢的强度随回火温度的升高呈现先增加后降低的趋势,而延伸率始终保持在25%以上,且回火温度为480℃时的强度最高。结合微观组织和力学性能分析结果确定480℃为最佳回火温度,该温度下Fe 3C碳化物在马氏体基体内均匀弥散分布,显著增强了析出强化效应。此外,Nb、V微合金化进一步优化了Q355B钢的组织结构,促进了棒状MC型碳化物的析出。在480℃回火后,Q355B钢和Nb-V-Q355B试验钢的屈服强度分别达到469 MPa和582 MPa,延伸率分别为26.5%和25.0%。由此可见,Nb、V微合金化在确保良好塑性的同时,使屈服强度提升了113 MPa。
Effect of Nb and V microalloying on microstructure and mechanical properties of Q355B steel after normalizing,quenching,and tempering were studied.The results show that Nb and V microalloying introduces undissolved spherical MC carbides at austenite grain boundaries,which inhibits boundary movement at high temperature,leading to significant grain refinement of the 900℃normalized and 900℃quenched steel.Additionally,Nb and V microalloying enhances the martensitic fraction of the quenched steel,thereby improving hardenability.After quenching at 900℃and tempering at 450-530℃,the strength of the tested steel increases first and then decreases with the tempering temperature increases,while the elongation remains consistently above 25%,and the strength is the highest when the tempering temperature is 480℃.Combined with the microstructure and mechanical properties analysis results,480℃is determined as the optimal tempering temperature.At this temperature,Fe 3C carbides are uniformly dispersed within the martensitic matrix,significantly enhancing the precipitation strengthening effect.Furthermore,Nb and V microalloying further optimizes the microstructure of the Q355B steel,promoting the precipitation of rod-like MC-type carbides.After tempering at 480℃,the yield strengths of the Q355B steel and the Nb-V-Q355B tested steel reach 469 MPa and 582 MPa,respectively,with elongations of 26.5%and 25.0%.These results indicate that Nb and V microalloying,while ensuring good ductility,leads to a 113 MPa increase in yield strength.
作者
张立冰
程陆凡
陈昊
石全强
严伟
罗贯虹
李瑞平
王威
Zhang Libing;Cheng Lufan;Chen Hao;Shi Quanqiang;Yan Wei;Luo Guanhong;Li Ruiping;Wang Wei(Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang Liaoning 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang Liaoning 110016,China;Fujian Road&Bridge Construction Group Co.,Ltd.,Fuzhou Fujian 350001,China)
出处
《金属热处理》
北大核心
2025年第4期48-54,共7页
Heat Treatment of Metals
基金
国家重点研发计划(2022YFB3705200)
国家自然科学基金面上基金(52271122)。
