GCr15轴承钢叶片环热处理后磁粉探伤异常的原因

Causes of abnormal magnetic particle detection of a GCr15 bearing steel blade ring after heat treatment

GCr15轴承钢叶片环经热处理后,进行磁粉探伤检查,发现其侧面沿轴向发生磁粉聚集现象,擦拭磁粉后表面恢复平整。采用化学成分分析、宏观观察、金相检验及能谱分析等方法,分析了该叶片环外表面发生磁粉聚集的原因。结果表明:该叶片环采用多只叠加及夹具紧固的方式进行淬火处理,淬火介质易残留在叶片环之间的间隙中且较难清洗,淬火介质中的氯离子诱发腐蚀,进而在距离叶片环外表面8.9μm处形成点蚀坑,点蚀造成磁粉聚集现象。

After heat treatment, magnetic particle testing was perofrmed on GCr15 bearing steel blade ring, it was found that the magnetic particle aggregation along the axial direction occurred on its outer surface. The surface returned to normal after wiping the magnetic powder. Using methods such as chemical composition analysis, macro observation, metallographic inspection and energy spectrum analysis, the reasons for the accumulation of magnetic particles on the outer surface of blade ring were analyzed. The results showed that the blade ring was quenched with multiple stacks and clamps. The quenching medium was easy to remain in the gap between blade rings and was difficult to clean. The chlorine ions of quenching medium induced corrosion, and then pitting pits were formed at a distance of 8.9 μm from the outer surface of the blade ring, magnetic particle aggregation was caused by pitting corrosion.