核电压力容器用厚钢板SA533B的组织及力学性能

研究了核电压力容器用钢SA533B显微组织的变化对其力学性能的影响,尤其对韧性的影响。显微分析结果表明,该钢板的组织主要为粒状贝氏体及少量多边形铁素体。通过对调质态(QT)和模拟焊后热处理(SPWHT)态SA533B钢板的常规力学性能、不同温度的夏比冲击韧性(KCV)及断裂韧度(KJC)的深入研究,结果表明SA533B厚钢板经SPWHT升高了韧脆转变温度,降低了冲击韧性及断裂韧度,但SPWHT对常规力学性能无显著的影响。扫描电镜及电子探针分析仪分析表明,经模拟焊后热处理SA533B板材组织中的析出相有不同程度长大且有钼的析出,板材的韧性降低与微观组织中的析出相和钼的析出密切相关。

Microstructure and mechanical properties of nuclear pressure vessel steel SA533B heavy plate

Microstructure and its effect on mechanical properties,especially toughness of a nuclear pressure vessel steel SA533B heavy plate were investigated.Granular bainite and some polygonal ferrite were identified in the steel by optical microscopy,scanning electron microscopy and transmission electron microscopy.Tensile properties at room temperature,Charpy impact values(KCV) and fracture toughness(KJC) were measured at different temperatures for the quenched-tempered(QT) and simulated post weld heat treatment(SPWHT) SA533B steel heavy plate,respectively.The results show that SPWHT increases the ductile-brittle transition temperature and decreases the KJC and KCV of the steel,however,no significant effects on its tensile properties are observed.The analysis of SEM and electron probe micro-analyzer(EPMA) shows that SPWHT coarsens the precipitation phases and promotes the precipitation of molybdenum precipitates.The decrease of toughness of the steel is related to the coarsening of precipitates and precipitation of molybdenum precititates.