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采用可控速热处理炉对核压力容器用SA508Gr.4N钢消除组织遗传性现象进行研究。为模仿大锻件锻后不同位置晶粒尺寸差异较大现象,对试验钢进行不同温度预粗化处理。设计了A和B两种方案消除试验钢的组织遗传性,结果表明:经方案A即等温退火+亚温正火+正火处理后,得到细小且均匀的晶粒,晶粒等级由2~9级细化为7.5~8.0级,该方案可有效消除SA508Gr.4N钢的组织遗传性现象。观察了等温退火、亚温正火和高温回火后试验钢组织的变化,分析了微观组织变化对消除试验钢组织遗传性的影响。
Study on eliminating the hereditary phenomenon of SA508Gr.4N steel used in nuclear pressure vessel by controlled speed heat treatment furnace. In order to simulate large forging large differences in grain size at different locations, the test steel pre-roughening at different temperatures. A and B programs were designed to eliminate the histological inheritance of the test steel. The results showed that after the solution A is isothermal annealing + sub-temperature normalizing + normalizing treatment, fine and uniform grains were obtained, the grain size ranged from 2 ~ 9 levels of refinement for the 7.5 to 8.0 level, the program can effectively eliminate SA508Gr.4N steel hereditary phenomenon. The changes of the microstructure of the test steel after isothermal annealing, normalizing at the mild temperature and tempering at the high temperature were observed. The effects of the microstructure changes on the histological inheritance of the test steel were analyzed.