凝固速度对高铬铸铁M_7C_3型初生相的影响

Effect of Solidification Rate on Primary Phase M_7C_3 of High Chromium Cast Iron

采用液态金属冷却的定向凝固设备,研究了凝固速度对3.35wt%C-27.5wt%Cr高铬铸铁原位生长复合材料初生M7C3型碳化物的影响。结果表明,凝固速度较高时初生M7C3型碳化物为空心或实心的六边形,随着凝固速度的降低,出现了U形和L形M7C3型碳化物;实心六边形、U形和L形初生相M7C3型碳化物横截面的硬度值为HV 2500左右,而空心六边形碳化物的硬度值为HV 1550左右;初生相M7C3型碳化物在定向凝固过程中具有两种生长方向。

The effect of solidification rate on the primary M7C3 phase of high chromium cast iron insitu composite with the composition of Fe-3.35wt%C-27.5wt% Cr was studiedby the unidirectional solidification of liquid metal cooling. The results show the cross section morphology of primary phase MTC3-type carbides is hexagonal and hollow hexagonal at high solidification rate, and with decrease of solidification rate, the cross section morphology of primary phase tends to be in U and L shape. The hardness of hexagonal, U and L shape primary phase MTC3-type carbides is about HV 2500, but the hollow hexagonal is about HV 1550, which indicates that the primary carbide M7C3 has two growth directions during the process of unidirectional solidification.