CrMn铸钢锤头是竖井式粉煤机主件,直接由22千瓦异步电机(π=1740转/分,V=380伏)带动。启动时无爬行速度,工件条件恶劣,技术要求严格。因此,精铸后热处理的好坏是产品工作可靠性与使用期限的关键环节。过去采用连续冷却转变工艺,淬火后及最后退除“耳部”高硬度时,均出现热处理逾限应变裂纹。使用中亦不断发生脆断现象,最长不过十几天,最短只有几小时,严重影响了机组的正常运转。后来我们经分析研究与试验,采用了预淬等温强化处理,获得了 CrMn cast steel hammerhead is the main shaft of the shaft-type coal pulverizer, driven directly by a 22 kW asynchronous motor (π = 1740 rpm, V = 380V). Start without crawling speed, poor workpiece conditions, strict technical requirements. Therefore, the quality of heat treatment after casting is the key to product reliability and service life. Over the past continuous cooling transformation process, quenching and the final removal of the “ear” high hardness, there are heat treatment over the limit strain cracks. The use of brittle break occurs, the longest but a dozen days, the shortest only a few hours, seriously affecting the normal operation of the unit. Later, we analyzed and experimented, using pre-quenching isothermal treatment, obtained