60Si2Mn热卷弹簧纵向裂纹的原因分析

针对60Si2Mn圆钢在卷簧淬火后出现纵向开裂的问题，分析了试样裂纹形貌、裂纹分布特征及裂纹贯穿情况；结合金相显微镜、扫描电镜对60Si2Mn圆钢金相组织、脱碳情况及高温氧化物进行了分析研究。结果表明，该纵向裂纹是由于连铸坯表面存在缺陷而导致的，在圆钢轧制过程中暴露和扩展，在组织应力的作用下，裂纹迅速扩展成为沿轧制方向分布的淬火裂纹。

Cause analysis of the quenching-cracking for hot-forging 60Si2Mn spring

For the problem of vertical cracking of 60Si2Mn spring after quenching,the crack morphology,crack distribution and crack penetration of the specimen were analyzed.The metallographic structure,decarburization and high temperature oxides of 60Si2Mn round steel were studied with metallographic microscope and scanning electron microscope.The results show that the longitudinal crack is caused by the defect of the surface of the continuous casting billet,which is exposed and expanded during the round bar rolling process.Under the action of the tissue stress,the crack rapidly expands into a quenching crack distributed along the rolling direction.