高碳中合金钢DM4的预处理工艺对碳化物转变及形貌的影响

The effect of pre-treatment on carbide transformation and morphology of Cr-W-Mo-V medium-alloy high carbon steel DM4 was investigated in this paper. The results show that there are multiple tapes of carbides (M3C、M23C6、M7C3、M6C、MC) in the steel annealed. The morphology of carbide in the annealing microstructure largely relate to the process before annealing. There are disperse particles of carbides and fine tactic clavicorn carbides in the ferritic matrix or the sheet pearlite at 820-860℃ by annealing. The spherical carbides in the ferritic matrix can be obtained by isothermal annealing at 680-720℃ after heating at 800℃. The morphology of carbides with different pre-treatment process relate to carbide transformation, which can be described accurately by calculating based on phase equilibrium thermodynamic.