螺杆心部空洞形成原因分析

ANALYSES OF CAVITY FORMATION REASON INSIDE A SCREW POLE

经对带有空洞的B7M20螺杆样品的宏观和微观检查和分析,结果表明螺杆心部的空洞为氢致开裂(HIC)所致。空洞是在滚牙至最终热处理之间形成的。螺杆心部具有高的残余应力、较严重的碳偏析及拉拔后的酸洗为螺杆心部出现HIC空洞提供了条件。

The cavities inside a screw pole were studied based on macro and micro observations and analyses. Results show that the cavities were caused by hydrogen-induced cracking (HIC) during cold rolling before last treatment. Residual stress, carbon segregation and acid cleaning after cold drawing played decisive roles in the hydrogen-induced cracking.