高铬铸铁过流冷却过程中初生相的细化球化

Refining and spheroidizing of primary phase in high Cr cast iron during inclined plate cooling

采用过流冷却法制备高铬铸铁半固态浆料,对初生相细化球化机理进行研究。结果表明,在冷却体作用下,熔体中大量快速形核长大的初生相通过物理、冶金作用分解和熟化成细小的等轴状颗粒而达到细化球化。树枝状初生奥氏体通过枝晶臂熔断和主干弯曲折断而细化球化,早期以枝晶臂熔断为主,后期以主干在剪切力作用下弯曲折断为主;高硬度的M7C3型初生碳化物通过横向折断和纵向分裂而达到细化球化,早期以横向折断为主,后期以纵向分裂为主。

The refining and spheroidizing mechanism of primary phase in semi-solid slurry of high Cr cast iron during the course of inclined plate cooling was studied. The results show that the primary phase nucleating and growing rapidly in the molten metal is separated or split and ripened to fining and spheroidizing particles under a series of physical and metallurgical processes. The refinement and spheroidization of primary austenite grains are accomplished by melting off of dendritic arms and bending off of trunk stems from the dendritic primary austenite grains. Mechanism of melting off of dendritic arms operates dominantly at the early stage during the inclined plate cooling, but bending off of trunk stems prevails at the late stage. The refinement and spheroidization of primary M7 C3 carbides are accomplished by cross breaking off and splitting off from the coarse carbide bars. Mechanism of cross breaking off operates dominantly at the early stage and the mechanism of splitting off prevails at the late stage for the high Cr cast iron during the inclined plate cooling.