SA508Gr.4N钢连续冷却组织转变特性  

Microstructure Transformation Characteristics of SA508Gr.4N Steel During Continuous Cooling

作　　者：万莉 卜恒勇 李绍宏[1] 李萌蘖 熊茹[2] 郑善举 WAN Li;BU Hengyong;LI Shaohong;LI Mengnie;XIONG Ru;ZHENG Shanju(Facultyof Materials Science and Engineering,Kunming University of Scienceand Technology,Kunming 650093,China;State Key Laboratory for Nuclear Fuel and Materials,Nuclear Power Institute of China,Chengdu 610213,China)

机构地区：[1]昆明理工大学材料科学与工程学院,昆明650093 [2]中国核动力研究设计院反应堆燃料及材料重点实验室,成都610213

出　　处：《有色金属工程》2022年第8期46-54,共9页Nonferrous Metals Engineering

基　　金：反应堆燃料及材料重点实验室基金(STRFML-2020-03);云南省基础研究计划项目(202101AU070152)。

摘　　要：结合物理模拟实验、显微组织观察和硬度测定研究了新一代反应堆压力容器用SA508Gr.4N钢的连续冷却组织转变特性。结果表明:SA508Gr.4N钢产生贝氏体相变的临界冷却速率为0.5℃/s;当冷却速率为1~30℃/s时,相变产物为板条马氏体,硬度值高达470 HV;当冷却速率为0.5~0.02℃/s时,相变产物为贝氏体和马氏体,且随着冷却速率的降低,贝氏体含量逐渐增加,贝氏体组织中可见呈粒状、短棒状的微细碳化物,硬度值低至400 HV;采用Koistinen-Marburger方程描述SA508Gr.4N钢马氏体转变动力学,拟合得到马氏体转变起始温度为345.4℃,动力学参数为0.031 4,适用于准确预测≥20%的马氏体转变量与温度之间的关系。Microstructure transformation characteristics by continuous cooling of SA508 Gr.4 N steel for next generation nuclear pressure vessels were subjected to physical simulation experiment,microstructure observation and hardness measurement.Results show that critical cooling rate of SA508 Gr.4 N steel for bainitic transformation is 0.5℃/s.When cooling rate is 1~30℃/s,transformation products are lath martensite with hardness up to 470 HV.When cooling rate is 0.5~0.02℃/s,bainite and martensite are transformation products,and as cooling rate decreases,bainite content increases gradually,granular and short rod-shaped fine carbides can be seen in the bainite structure,and hardness value is as low as 400 HV.Koistinen-Marburger equation is used to describe martensitic transformation kinetics of SA508 Gr.4 N steel,fitting results showed that initial martensitic transformation temperature is 345.4℃and kinetic parameter is 0.0314,which can accurately predict the relationship between martensitic transformation and temperature with transformed amount exceeding 20%.

关 键 词：SA508Gr.4N钢 组织转变特性 临界冷却速率 马氏体转变动力学 

分 类 号：TG142[一般工业技术—材料科学与工程]