摘要
通过光学显微镜、扫描电镜、X射线衍射仪、硬度、室温拉伸试验等研究了循环淬火回火对18CrNiMo7-6渗碳齿轮钢显微组织与力学性能的影响规律。结果表明,经过3次淬火回火循环后,渗层奥氏体晶粒尺寸由原始状态的31.3μm细化至7.6μm,心部奥氏体晶粒尺寸由27.9μm细化至8.4μm,且晶粒均匀性显著改善。循环过程中,马氏体向奥氏体转变产生的相变储能提供了晶粒细化驱动力,而多次循环后残余应力及位错的逐步消除限制了再结晶大幅细化效果。循环后渗层表面硬度维持在约700 HV,高于原始状态,而心部硬度变化不明显。抗拉强度和屈服强度均随循环次数增加而提高,其中抗拉强度在3次循环后达到峰值2066 MPa,屈服强度在2次循环后达到峰值1452 MPa。强度的提升主要归因于位错强化、细晶强化及析出强化的协同作用。
Effect of cyclic quenching and tempering on the microstructure and mechanical properties of 18CrNiMo7-6 carburized gear steel was investigated by using optical microscope,scanning electron microscope,X-ray diffractometer,hardness measurements,and room-temperature tensile testing.The results show that after three cycles of quenching and tempering,the austenite grain size in the carburized layer is refined from 31.3μm to 7.6μm,while the core grain size is decreased from 27.9μm to 8.4μm,and the uniformity of the grains is significantly improved.During the cycling process,the phase transformation energy storage from martensite to austenite provides the driving force for grain refinement.However,the gradual elimination of residual stress and dislocations after multiple cycles limits the effectiveness of recrystallization-driven refinement.The hardness of the carburized surface layer is maintained at approximately 700 HV,higher than that in the original state,while the core hardness remains unchanged.The tensile strength and yield strength are increased with the number of cycles.The tensile strength reaches the peak at 2066 MPa after three cycles,while the yield strength reaches its maximum of 1452 MPa after two cycles.The strength enhancements are primarily attributed to the synergistic effects of dislocation strengthening,grain refinement strengthening,and precipitation strengthening.
作者
刘鑫
车翰林
尉文超
杨昊
何肖飞
朱嘉
张弛
王毛球
Liu Xin;Che Hanlin;Yu Wenchao;Yang Hao;He Xiaofei;Zhu Jia;Zhang Chi;Wang Maoqiu(Research Institute of Special Steels,Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China;School of Materials Science and Engineering,Kunming University of Science and Technology,Kunming Yunnan 650093,China;Key Laboratory of Advanced Materials of Ministry of Education,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;China Academy of Machinery Beijing Research Institute of Mechanical&Electrical Technology Co.,Ltd.,Beijing 100083,China)
出处
《金属热处理》
北大核心
2025年第12期104-110,共7页
Heat Treatment of Metals
基金
钢铁研究总院有限公司自主投入项目(事25T60310Z)。
关键词
齿轮钢
渗碳
循环淬火回火
晶粒细化
力学性能
gear steel
carburizing
cyclic quenching and tempering
grain refinement
mechanical properties
