Microstructural evolution of high manganese steel solidified under superhigh pressure

The microstructure of high manganese steel solidified under 6 GPa was examined by using OM, FEGSEM and TEM for analysis of influences of high pressure on phase transformation and the morphology of carbides. The results indicate that the microstructure consisting of complete equiaxed dendrites, the mean dendrite arm spacing of which was ~ 18 μm, was remarkably refined under 6 GPa. The change of the morphology of carbides from needle-like and rhombic carbide (M3C) to nodulized cubic carbide (M23C6) was observed by TEM, which is associated with the undercooling and distribution of trace elements of manganese. The diameter of spheroidal carbides is approximately between 150 nm and 200nm.