白点缺陷的检验方法及微观形貌介绍

The Introduction of Test Method and Micro Morphology of Flakes Defect

本文介绍了白点的几种常用检验方法,即低倍酸侵检验、探伤检验、低倍断口检验、扫描电子显微镜下微观断口检验,提出检验白点要按照不同需求选择适合的方法。又详细介绍了几种钢调质态白点微观形貌,钢种42CrMoS4调质态白点以颗粒状夹杂物或微裂纹为核心扩展形成,微观形貌为碎条状解理;钢种G20Cr2Ni4白点区域无夹杂物,微观形貌为冰糖状沿晶断裂;钢种5CrNiMo调质态白点区域有条状夹杂物,微观形貌为浮云状断裂,白点边缘可见鸡爪纹。由此可见,热处理状态相同的不同钢种,白点的微观形貌不一定相同。

This paper introduces several common inspection methods of flakes,namely low power acid invasion inspection,flaw detection inspection,low power fracture inspection and micro fracture inspection under scanning electron microscope.It is proposed that suitable methods should be selected according to different needs.The micro morphology of quenched and tempered flakes of several steels is introduced in detail.The quenched and tempered flakes of steel 42CrMoS4 are formed with granular inclusions or microcracks as the core,and the micro morphology is broken strip cleavage;There is no inclusion in the flakes area of steel G20Cr2Ni4,and the micro morphology is crystal sugar intergranular fracture;There are strip inclusions in the quenched and tempered flakes area of steel 5CrNiMo,the micro morphology is floating cloud fracture,and chicken claw patterncan be seen at the edge of the flakes.It can be seen that the micro morphology of flakes is not necessarily the same for different steel grades with the same heat treatment state.