动力车轴表面坑状缺陷分析

Analysis of Pit Defects on Surface of Powered Axles

为研究动力车轴卸荷槽表面坑状缺陷成因及性质,采用光学显微镜初步检测车轴的微观组织和晶粒度;应用扫描电镜观察车轴内孔表面缺陷处的微观形貌特征;利用能谱分析仪测定车轴化学成分和车轴表面缺陷处的微观组织,确定缺陷处物质类型;通过微量水份测定仪等测定水含量和油脂成分。结果显示,腐蚀坑内含有P,S,K和Ca等元素,Fe的主要形式是Fe2O3。推断表面缺陷为电化学腐蚀造成,属于局部腐蚀,具体为溃疡腐蚀。

To study the contributing factors and nature of pit defects on the compensating groove surface of poweredaxles,an optical microscope is used to preliminarily detect the microscopic structure and grain size number of the ax-le. A scanning electron microscope is applied to observe the microcosmic shape characteristics at the surface defect ofthe inner bore for the axle. With an energy dispersive spectrometer,the chemical compositions of the axle and the mi-croscopic structure at the surface detect of the axle are determined,with the type of materials at the defect also veri-fied. The water content and the grease composition are determined via a micromoisture analyzer. The result indicatesthat,elements such as P. S. K and Ca,etc. are contained in the etch pit,with the main iron form of Fe2O3. It can bededuced that the surface defect is caused by electrochemical corrosion,which is of local corrosion,namely,ulcer-ative corrosion.