核电厂冷却水泵叶轮裂纹缺陷的成因及解决方法

Causes and Solutions of Cracking Defect on Cooling Water Pump Impellers in Nuclear Plants

针对冷却水泵叶轮出现裂纹缺陷的问题,以某工厂生产冷却水泵为例,从材料铸造工艺、力学性能、裂纹形貌等方面对裂纹缺陷产生的原因进行了分析,并对比了两种冷却水泵叶轮铸造工艺的区别。研究结果表明,该工厂生产叶轮的力学性能较差,在裂纹周围有沿晶面断裂特征,且其金属结构不均匀,造成叶轮裂纹缺陷的主要原因为铸造工艺存在问题。针对工艺方面存在的问题,分别从铸造工艺和热处理工艺两个方面提出改进方案,以期为相关人员提供参考。

This paper focuses on a case of cracking defect found on the impeller of an actual nuclear plant′s cooling water pump,and conducts causal analysis from the aspects of casting process,mechanical properties,crack morphology,etc.of the impeller material,as well as makes a comparison to reveal differences between two impeller casting processes.It describes in detail the cracking defect of the impeller which is manifested by intergranular fracture characteristics around the cracks and is mainly attributed to problematic-casting-process-induced inferior mechanical properties and uneven metal structure.In response to the existing problems in impeller production process,improvement scheme is proposed from casting process and heat treatment process,which may be helpful for relevant personnel.