回火时间对核电压力容器用钢的组织及性能的影响.pdf

回火时间对核电压力容器用钢的组织及性能的影响·1·
回火时间对核电压力容器用钢的组织及性能的影响
李传维韩利战刘庆冬顾剑锋晏广华张伟民
(上海交通大学材料科学与工程学院材料改性与数值模拟研究所,上海 200240)
摘要以核电压力容器用 钢为研究对象,研究了显微组织和第二相随回火时间的变化规律及其对性能
的影响。结果表明,在 650℃回火时,粒状贝氏体中的 M/A 岛首先分解为铁素体基体和堆积的长条状 Fe3C 碳化物;
随后长条状的碳化物长大球化,M/A 岛分解形成的铁素体发生合并结晶为大的铁素体板条;当回火时间进一步延长,
Fe3C 碳化物数量减少并粗化,新生成的 M2C 碳化物弥散分布在铁素体基体中。随着回火时间延长,材料的强度逐
渐下降,冲击性能先上升至极值后逐渐恶化。结果表明,回火过程中基体组织的软化效应、合并再结晶,M-A 岛
分解程度,碳化物的类型、形貌、尺寸和分布是影响材料力学性能的重要因素,其中晶界大颗粒碳化物能够显著降低
晶界的结合强度,改变裂纹非稳定扩展的临界断裂应力,是 SA508 钢冲击韧性达到峰值后下降的主要的原因。
关键词核电压力容器用钢,回火时间,组织,性能
The Effect of Tempering Time on Microstructure and Mechanical
Properties of a Reactor Pressure Vessel Steel1
Li Chuanwei, Han Lizhan, Liu Qingdong, Gu Jianfeng,Yan Guanghua, Zhang Weimin
(Institute of Materials Modification and Modeling, School of Materials Science and Engineering, Shanghai
Jiao Tong University, Shanghai 200240, China)
Abstract This paper indicates microstructure and their influence on the properties of the nuclear reactor power pressure
vessel steel during tempering at 650°C. The results show that: the M/A (Martenite/Austenite) constituents with higher
carbon content in the granular bainite are first broken up into the ferrite lathes and accumulated arbides. Later, the
ferrite lathes which posed from martensite island undergoes merged crystallization and broaden. Fe3C grew bigger
and spheroidized. At