QT600球铁等离子弧熔凝温度场数值模拟及组织分析

采用等离子弧对QT600球铁进行了熔凝处理,利用扫描电镜、显微硬度仪对熔凝试样各区域的组织及显微硬度进行测试分析,并且在综合考虑等离子弧的挖掘作用、材料非线性、熔化潜热等对等离子弧熔凝温度场影响的基础上,采用双椭球热源建立了QT600等离子弧熔凝连续三维移动瞬态温度场有限元模型。结果表明,熔凝层显微硬度达到600～1060 HV,熔凝层组织为马氏体+渗碳体+残留奥氏体,模拟熔池最高温度达到1808℃,熔凝区模拟的形状及尺寸与实际基本吻合。

Numerical simulation of temperature field and microstructure of plasma arc remelted QT600 nodular cast iron

Plasma arc remelting treatment was conducted on QT600 nodular cast iron.Microstructure and micro-hardness of the melted zone and heat affected zone were studied by SEM and micro-hardness tester.A FEA model of transient temperature field of three-dimension moving for plasma arc remelting on QT600 nodular cast iron was built up by taking into account of the characteristics of plasma arc and the thermal physical parameters of materials.The results show that the microstructure of the remelted zone consists of martensite,cementite and retained austenite,its microhardness reaches 600-1060 HV,and the simulation results of remelting zone are in accordance with the experimental results.Temperature near the surface of the remelting pool is the highest,and up to about 1808 ℃.