Study on primary carbonitrides in H13 steel based on the two-sublattice model
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摘要: 實驗證明H13鋼中存在三類初生碳氮化物，包括富V和C的（Vx，Mo1-x）（Cy，N1-y）、富Ti和N的（Tix，V1-x）（Cy，N1-y）及富V和C的（Tix，V1-x）（Cy，N1-y），部分存在形核核心.基于雙亞點陣模型和凝固偏析模型分析計算H13鋼凝固過程中元素含量變化，考慮初生碳氮化物中元素間的相互作用，根據三類碳氮化物中合金元素含量和C/N比值不同，對各碳氮化物的生成自由能進行分析.理論研究指出富Ti和N的（Tix，V1-x）（Cy，N1-y）在固相率為0.90時即可生成，而富V和C的（Tix，V1-x）（Cy，N1-y）在固相率大于0.96才可生成，兩類碳氮化物的臨界生成固相率fP均隨固溶Ti和N含量的增加而減小.（Vx，Mo1-x）（Cy，N1-y）的臨界生成固相率與x值密切相關，x減小時fP降低，粒子尺寸增加，實驗與理論分析吻合良好.根據錯配度分析氧化物和碳氮化物對H13鋼中初生碳氮化物異質形核的作用.Abstract: Three kinds of primary carbonitrides were classified in H13 hot work die steel through experiment,including (Vx,Mo1-x)(Cy,N1-y) rich in V and C,(Tix,V1-x)(Cy,N1-y) rich in Ti and N,and (Tix,V1-x)(Cy,N1-y) rich in V and C,some having a core in the center.The element variation and Gibbs energy of the carbonitrides during H13 solidification were analyzed based on the solidification segregation model and the two-sublattice model,taking the interaction between components into account as well as the alloying element content and C/N ratio of the three types of primary carbonitrides.It is found that Tiand N-rich (Tix,V1-x)(Cy,N1-y) forms when the solid fraction reaches 0.9,while the other Vand C-rich (Tix,V1-x)(Cy,N1-y) generates when the solid fraction is greater than 0.96 during solidification.The critical solid fraction for the formation of these two (Tix,V1-x)(Cy,N1-y) decreases with increasing Ti and N contents soluted in the carbonitrides.The formation of (Vx,Mo1-x)(Cy,N1-y) during solidification can be affected by the x value.The critical solid fraction decreases as less vanadium is soluted in (Vx,Mo1-x)(Cy,N1-y),leading to larger size carbonitrides demonstrated by the models,which fit well with experimental data.The influence of oxides and carbonitrides on heterogeneous nucleation for the carbonitrides was also researched through lattice misfitting analysis.
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Key words:
- hot die steel /
- carbonitrides /
- segregation /
- sublattices /
- composition
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參考文獻
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