冷轧工作辊工频淬火开裂原因分析

Cracking analysis of cold mill work rolls during power frequency induction hardening

利用ZEISS-AXIO金相显微镜、ZEISS-MA10扫描电子显微镜对9Cr2Mo钢冷轧工作辊工频淬火开裂后的断口进行观察,分析了工作辊淬火开裂的原因。结果表明,9Cr2Mo冷轧工作辊淬火开裂断口形貌分别由剪切唇区、放射区以及纤维区3部分组成。断口裂纹源处有明显的白点,其产生原因主要是氢和内应力的共同作用所致。改善方法首先应提高辊坯的冶金质量,降低辊坯中的氢含量;其次应改进锻后热处理工艺,例如采取降低白点敏感性的锻压方法,并对锻后辊坯进行充分的扩氢退火,降低辊坯氢含量和内应力。

By means of OM and SEM the fracture appearance of 9Cr2Mo steel cold mill work rolls during power frequency induction hardening was observed and the cracking cause was analyzed.The results indicate that the fracture appearance of 9Cr2Mo steel cold-roller during quenching mainly consists of three parts： shear lip zone,radical zone and fibrous zone.There is obvious flake spot at cracks source.The cause of flake spot is combined action of hydrogen and internal stress.The measures of preventing flake spot included the improving of metallurgical quality and heat treatment to reduce the content of hydrogen and internal stress in steel are put forward.