聚丙烯挤出机螺钉断裂原因分析

Analysis on Fracture Reason of Screw in Polypropylene Extruder

某公司的聚丙烯25线挤出机出现挤出颗粒异常,原因为模板上固定螺钉发生多处断裂,为了探明螺钉出现断裂的过程,通过宏观检查、金相分析、化学成分分析、扫描电镜、能谱分析及硬度测试的分析方法,对发生断裂的螺钉进行了分析,探讨了断裂失效的原因。螺钉开裂为氢脆导致的延迟裂纹,由于电镀过程中氢原子渗入螺钉内部,同时电镀后未及时对螺钉热处理除氢,导致了螺钉的氢脆。

Abnormal extruded polypropylene particles appeared in 25 line extruder in a company which is caused by the fracture of the fixed screws on mould plate.In order to find out the fracture process of the screw,the fracture of the screw was analyzed by macroscopic observation,metallographic examination,chemical composition analysis,scanning electron microscopic analysis,energy spectrum analysis and hardness test,and the reason of the failure was discussed.The results show that the cracking of screw belongs to delayed crack due to hydrogen embrittlement,which is caused by hydrogen permeation into screws during electroplating,and does not dehydrogenated by heat treatment in time after electroplating leading to hydrogen embrittlement in screw.