焊后热处理对核反应堆压力容器用16MND5钢组织和性能的影响

Effect of Post-Weld Heat Treatment on Microstructure and Properties of 16MND5 Steel for Nuclear Reactor Pressure Vessels

采用光学显微镜、透射电子显微镜,通过拉伸、冲击和落锤试验等方法研究了焊后热处理温度和保温时间对16MND5钢的组织和力学性能的影响。结果表明:经模拟焊后热处理后16MND5钢的室温和350℃抗拉强度和屈服强度都呈下降趋势,且下降幅度随焊后热处理温度的升高和保温时间的延长而增大;焊后热处理时间的延长导致钢的冲击性能小幅度下降,焊后热处理温度对冲击性能的影响并不明显;焊后热处理后的钢基体中弥散分布的细小第二相粒子数量减少、尺寸增大,导致钢的强度降低。

Effect of post-weld heat treatment(PWHT),temperature and holding time on the microstructures and mechanical properties of 16MND5 steel was investigated by means of optical microscope,transmission electron microscope,tensile,impact and drop weight tests.The results showed that(a)both the tensile strength and yield strength of 16MND5 steel at room temperature and 350℃decreased after simulated PWHT,and the decreasing amplitude increased with the increase in PWHT temperature and the extension of holding time;(b)the extension of holding time of PWHT led to a slight decrease in the impact properties of the steel,while the effect of PWHT temperature on impact properties was not significant;(c)after PWHT,the fine second-phase particles dispersed in the steel matrix decreased in number and increase in size,resulting in a decrease in the strength of the steel.