Y15易切削钢孔洞分析及其预防

Hole analysis of Y15 free-cutting steel and its precautions

采用体视显微镜(SM)、金相显微镜(OM)、扫描电子显微镜(SEM)及能谱仪(EDS)等对Y15易切削钢孔洞形成的原因进行了分析。结果表明,孔洞两边的裂纹呈应力裂纹特征,是最后一次热轧后方坯冷速过快所致,而孔洞则产生于随后的冷拔过程中。通过将方坯轧后空冷改为进缓冷坑缓冷后,制作的零件再无孔洞出现。

The forming reactions of holes in Y15 free-cutting steel were analyzed by stereomicroscope( SM),optical microscopy( OM),scanning electron microscope( SEM) and energy disperse spectroscopy( EDS). The results showed that the cracks on both sides of the hole had characteristics of stress cracking,which were caused by too fast cooling rate of the square billet after the last hot rolling. The hole was formed during the subsequent cold drawing process. By modifying the air cooling of the square billet to slow cooling in burial pit,no holes were found in the parts anymore.