Effect of Different Nitriding Temperature on Secondary Recrystallization of Hi-B Steel with an Element of Cu

Abstract

In the microstructural evolution, the behavior of inhibitors with different nitriding temperatures during abnormal grain growth (AGG) of the Hi-B steel in the secondary recrystallization was studied in a wide range of annealing temperatures. It is found that the inhibitors are mainly (Al, Si, Mn)N and composite precipitation of Cu2S and AlN after nitriding annealing at 550 °C, whereas the inhibitors are mainly AlN and a small part of composite precipitation of Cu2S and AlN after nitriding annealing at 900 °C. 1000 °C is abnormal growth point of Goss grains at nitriding temperature of 550 °C, whereas the 1040 °C is abnormal growth point of Goss grains at nitriding temperature of 900 °C. The final annealing microstructure of nitriding annealing at 900 °C is better than the microstructure of nitriding annealing at 550 °C. Moreover, the average size and volume percentage of inhibitors, the Zener factor at different annealing temperatures implies that the nitriding technology with 900 °C is more suitable than that of nitriding technology with 550 °C for the AGG of the Hi-B steel in the secondary recrystallization.