Effect of Cu on Microstructures of Manganese Steel by EDXA and SEM

In order to investigate the distribution of Cu and Mg, and the effect of Cu on the microstructure of steels,manganese steels containing various Cu contents were annealed at 1260, 1100 and 1000℃, respectively, for 1 h and subsequently cooled to room temperature in the furnace to simulate the pre-rolling anneal. The results indicate that Cu is not microscopically segregated in the annealed steels. The scanning electron microscopy (SEM) observation shows that the main microstructure consist of ferrite and pearlite; the percentage of pearlite in the steels increases with increasing Cu content. The grain size reduces with the decrease of the annealing temperature. The results of energy dispersive X-ray analysis (EDXA) suggest that Cu content in pearlite is higher than that in ferrite, demonstrating that the microstructure-segregation of Cu occurred. However, the cast specimens show that Cu content in MnS and S-rich phases is high. In addition, Cu of 0.2%-0.4% could improve the distribution of MnS and S-rich inclusions. The optimal Cu content in steels and the optimal annealing temperature between 1100-1200 ℃ were determined.