摘要
The solidification characteristics and segregation behavior of solute elements Nb,Ni,Mn,Si,Cr and C in 0.3 wt.%Nb-310S steel were investigated using the isothermal solidification quenching experiment and Thermo-Calc calculation.The phase transformation for 0.3%Nb-310S steel under equilibrium condition can be summarized as follows:liquid(L)→L+γ(1406℃)→γ(1334℃)→γ+NbC(1322℃)→γ+NbC+M_(23)C_(6)(1006℃)→γ+NbC+M_(23)C_(6)→σ(755℃).The results showed that the solidification began with the formation of primary austenite dendrite.The volume fraction of the liquid phase decreased rapidly as the temperature decreased in the initial solidification stage,and then,the liquid phase fraction decreased slowly.When austenite formed,Mn and Ni were enriched in the solid phase,while Nb and C were rejected into the liquid.Nb was present the highest segregation coefficient in 0.3%Nb-310S austenitic stainless steel.The segregation of Nb was the most serious,followed by Mn,Ni and C.Cr and Si exhibited slight segregation during the solidification.The solidification was terminated by the formation of NbC phase.
基金
supported by Joint Fund of National Natural Science Foundation of China and Liaoning Province (No.U1708252)
Industrial Strong Foundation Project (TC190A4DA/35)
the Scientific Research Project of China Three Gorges Corporation (No.JD-YJ-05006).
