轧机导辊用白口铸铁热处理工艺的研究

Study on the Heat Treatment Process of White Cast Iron for Guide Roller of Mill

利用金相分析、硬度测定和X射线衍射技术,对轧机导辊用白口铸铁的热处理工艺进行了系统的研究。结果表明:铸态下的白口铸铁硬度值较高,基体组织主要为奥氏体,难以进行切削加工;采用适当的退火热处理,改变其基体组织、降低硬度后,切削加工性能大大改善;为保证轧机导辊的工作性能,采用980℃空淬+250℃回火热处理可得到最佳的组织与宏观硬度,即回火马氏体、一次碳化物以及少量的二次碳化物,硬度值达到HRC 63.7。

By means ofmetallographic microscope,Rockwell hardness test and X-ray diffraction method,the heat treatment process of white cast iron for guide roller of mill were studied.The results show that the hardness of the as-cast white cast iron was higher,the primary microstructure was the austenitic matrix,and it was difficult to cut and machine.By the appropriate annealing heat treatment,the matrix microstructure was changed and its hardness was decreased,the machinability was greatly improved.In order to guarantee the performance of guide roller of mill,the best tempering microstructure and hardness were obtained by air quenching at 980 ℃ and tempering at 250 ℃.The microstructure consisted of tempered martensite,eutectic carbides,and a small amount of secondary carbides.The hardness reached HRC 63.7.