Effect of Cooling Rate on the Microstructure and Precipitates of Directional Solidified 50W600 Non-oriented Silicon Steel

摘要

The microstructure, morphologies of precipitates in directional solidified 50W600 non-oriented silicon steel with three cooling rates (0.095, 0.33 and 4.28 ℃/s) were investigated. The results showed that the morphology of solid-liquid interface evolved from cellular to cellular dendritic, and then to dendritic with an increase of cooling rate. The grain size of specimen in the steady-state growth region decreased with increasing cooling rate. The precipitates in the steel were mainly four types as follows: AlN, MnS, AlN-MnS and Fe_3C. The amount and volume fraction of precipitates firstly increased and then decreased with increasing cooling rate, and reached maximum values in the specimen with a cooling rate of 0.76 ℃/s. The average size of precipitates decreased gradually with increasing cooling rate. The relationship between the average size of precipitates and cooling rate was D=75.762·R~(-0.190).