采用光学显微镜、扫描电镜以及能谱仪等仪器分析手段对LZ50钢车轴机加工后出现发纹的原因进行了分析。结果表明: 该车轴发纹是由于钢中的氧化铝类夹杂物在机加工时暴露于车轴表面而形成的缺陷; 同时提出了通过氩封浇注的方法来减少二次氧化所带来的氧化物夹杂, 从而提高了车轴的磁粉探伤合格率。

The reasons for hair cracks appearance on LZ50 steel axle surface after machining were analyzed by means of metallographic examination, scanning electron microscope analysis and energy dispersive spectroscopy analysis. The results show that alumina inclusions exposed on surface of the axle steel when machining, which resulted in the formation of hair cracks. Based on the finding, the alumina inclusions in the steel could be reduced efficiently by protecting with argon sealing casting, so the magnetic powders inspection qualified rate of the axle steel was improved.