H13热作模具钢大尺寸析出相特征及生成机制

Characteristics and generating mechanism of large precipitates in H13 tool steel

针对H13钢中大尺寸析出相的存在形式及形成机制进行研究。研究发现,H13钢中大尺寸析出相包含3类——富钒的(V,Mo,Cr,Fe)C类、富Mo-Cr的(V,Mo,Cr,Fe)C类及硫化锰。富钒的(V,Mo,Cr,Fe)C类大尺寸析出相形状多呈现长条形,尺寸达数十微米,部分依附于硫化锰形核的析出相成类椭圆形;富Mo-Cr的(V,Mo,Cr,Fe)C析出相无规则形貌,钼、铬原子分数比相差不大,钒原子分数稍低。根据复合大尺寸析出相的结合形式,可以推测出大尺寸析出相的析出顺序。硫化物首先析出,富钒类(V,Mo,Cr,Fe)C相随后,富Mo-Cr类(V,Mo,Cr,Fe)C相则最后析出。结合大尺寸析出相的成分特征,Thermo-calc计算结果与试验结果一致。

The characteristics of large precipitates in H13 tool steel were studied and the results were compared with the predicted solidification process calculated by Thermol-calc software to study the generating mechanism.The results showed that three kinds of large phases were existing in the as-cast ingot,which were V-rich（V,Mo,Cr,Fe）C phase,Mo-Cr-rich（V,Mo,Cr,Fe）C phase and manganese sulfide.For the V-rich（V,Mo,Cr,Fe）C phase,the shape of the majority big precipitates was strip and the size could be tens of microns,while a part of ones precipitating on manganese sulfide had an oval shape.For Mo-Cr-rich（V,Mo,Cr,Fe）C phase,the precipitates were irregular phase,the content of Mo was similar to that of Cr and the content of V was slightly lower.The precipitation order could be speculated according to the combining form of complex large phase.Sulfide,V-rich（V,Mo,Cr,Fe）C phase and Mo-Cr-rich（V,Mo,Cr,Fe）C phase were precipitated successively.The calculation results of Thermo-calc were basically consistent with the experimental results combined with the component characteristics of large precipitates.