两相区淬火对7Ni钢微观组织和力学性能的影响  

Effect of Quenching in Dual-phase Region on Microstructure and Mechanical Properties of 7Ni Steel

作　　者：许立雄 武会宾 牟丹 XU Li-xiong;WU Hui-bin;MOU Dan(Collaborative Innovation Center of Steel Technology,University of Science and Technology Beijing,,Beijing 100083,China;Institute of Engineering Technology,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学钢铁共性技术协同创新中心,北京100083 [2]北京科技大学工程技术研究院,北京100083

出　　处：《材料工程》2018年第8期113-119,共7页Journal of Materials Engineering

基　　金：国家自然科学基金项目(51474031)

摘　　要：利用X射线衍射仪、扫描电镜和热膨胀仪,研究两相区淬火温度和保温时间对7Ni钢显微组织及力学性能的影响。基于热膨胀曲线,定量地测量了7Ni钢在淬火+两相区淬火+回火(QLT)工艺各阶段的逆转奥氏体生成量及转变速率,揭示逆转奥氏体的转变过程。结果表明:逆转奥氏体在QLT工艺中的转变依次经历了淬火保温、淬火冷却、回火保温、回火冷却四个过程。适当升高两相区淬火温度和延长保温时间,有利于回火过程中逆转奥氏体的转变,并促进其均匀分布,从而使7Ni钢强度降低,塑韧性增强。两相区淬火工艺为660℃保温30min时,7Ni钢综合力学性能达到最佳,并完全满足标准ASTM A553规定的9Ni钢的力学性能要求。The influence of quenching temperature and holding time in dual-phase region on microstructure and mechanical properties of 7Ni steel was studied by X-ray diffractometer,scanning electron microscopy and thermal dilatometer.Based on the thermal expansion curve,the production and transformation rate of reversed austenite of 7Ni steel under each stage of the QLT treatment was quantitatively measured,and the transformation process of reversed austenite was revealed.The results indicate that the transformation of reversed austenite during QLT treatment successively goes through four stages：quenching temperature holding,quenching cooling,tempering temperature holding and tempering cooling.Appropriately improving the quenching temperature in dual-phase region and extending the holding time is beneficial to the transformation of reversed austenite during tempering,and also promotes its uniform distribution,which consequently reduces the strength and enhances the ductility as well as toughness of 7Ni steel.Under the quenching in dual-phase region treatment at 660℃for 30 min,the comprehensive mechanical properties of the 7Ni steel are the best,which completely meet the mechanical property requirements of 9Ni steel stipulated by ASTM A553.

关 键 词：7Ni钢 两相区淬火 逆转奥氏体 热膨胀曲线 

分 类 号：TG142.1[一般工业技术—材料科学与工程]