电渣重熔H13钢中一次碳化物形成机制

 H13热作模具钢在电渣重熔过程中会在凝固末端形成粗大的碳化物及氮化物，由于生成温度高，热稳定性好，会保留到最终热处理状态，对钢材的性能产生严重影响。应用偏析模型计算并说明了凝固过程生成粗大的共晶碳化物和氮化物的可能，当固相率达到0.82时由残余液相生成TiN，随着温度进一步下降在接近凝固终点时生成VC0.88，由于碳化物中固溶了其他合金元素，认为生成的VC0.88的活度不为1，试验检测的碳化物合金元素含量与理论假设基本吻合。对粗大的碳氮化物的特点及细化减少碳化物进行简单讨论。

Formation Mechanism of Primary Carbide in H13 Steel During Electroslag Remelting Process

The eutectic carbide and nitride could precipitate the end of solidification during electroslag remelting process. Because of the high precipitation temperature and thermal stability they would finally remain in the product even through heat treatment, resulting in severe effects on mechanical performance for H13 hot work die steel. The segregation model was used to calculate and explain the possibility of forming coarsening eutectic carbide and nitride in the solidification process. When the solid fraction is 0.82, TiN can precipitate from the residual liquid and it is when approaching the end point of solidification that VC0.88 is formed with decreasing temperature. For the other soluble elements in the carbide, the carbide activity can’t be regard as unity, and the EDS analysis agrees well with the theoretical assumption. There is also a simple discussion on the characteristics of large carbide and nitride as well as refining size and reducing the amount of the primary carbide.