关键词: 氮, 高导热性奥氏体锰钢, 晶粒度, 细化

Abstract: The effect of solid solution of nitrogen element on crystal grain of developed austenitic manganese steel with high thermal conductivity is studied. The results indicate that the crystal grain of manganese steel in casting is affected by the nitrogen in the interface between crystal and liquid steel as surfactant, and the diffusion of relevant atoms are hindered by nitrogen, so that free energy of critical nucleation will be increased, homogeneous nucleation rate of crystal raised and growing velocity of crystal lowered, and crystal grain will be refined finally in steel casting. The effect degree of nitrogen on crystal grain of steel is affected by nitrogen content. During heat treatment, because of covalent bond between nitrogen and iron and manganese atoms, the diffusion of iron and manganese atoms will be hindered due to the existence of nitrogen at boundary of crystal or the attachment of nitrogen on the face of crystal, so that growing velocity of crystal will be lowered and the crystal grain of steel can be controlled. The new kind of austenitic manganese steel decreases the content of manganese below 8%, the content of carbon to about 1%, and the content of nitrogen about 0.07%, the crystal grain grade of developed steel reaches the class 4, and its mechanical properties meet those required by standard manganese steel Mn13.

Key words: nitrogen, austenitic manganese steel with high thermal conductivity, crystal grain, refining