304不锈钢叶轮后盖板疲劳断裂原因分析

Study on the Fatigue Fracture of 304 Stainless Steel Impeller Rear Cover

叶轮是热水泵关键过流部件,是热水泵能量转换的核心部件,也是运行过程中最容易破坏的部件。某厂橡胶装置后处理热水泵叶轮的后盖板发生了断裂,为寻找断裂原因,进行了宏观检查、材质分析、金相检验、扫描电镜观察和能谱分析,结果表明:铸造缺陷是叶轮后盖板断裂的主要原因。铸造缺陷处发生应力集中从而形成裂纹源,在交变载荷的作用下,裂纹不断扩展,最终导致疲劳断裂。

Impeller is the key flow passage component inside hot water pump,which is the core component for pump energy conversion and the most easily damaged part in operation.Analysis scheme was adopted in response to fractures occurred in impeller rear cover of a rubber unit,such as macroscopic examination,material analysis,metallographic examination,scanning electron microscope and energy spectrum analysis.The results revealed that casting defect is the main cause.Stress concentration initiated from casting defects,resulting in the formation of crack sources.Under the action of alternate load,the cracks continue to expand and eventually lead to fracture.