中文摘要：

利用Thermo-calc热力学计算软件和TCFE-3数据库，对含Nb高Mo热作模具钢成分进行了优化。探讨了Cr、Mo元素含量对富Cr的M23C。型碳化物固溶温度的影响，得到元素Cr、Mo合适的质量分数分别为4．0％和2．5％。此外，还讨论了元素Nb对（V、Nb）C型碳化物的固溶温度的影响趋势，当添加0．03％Nb时可将固溶温度由1150℃提高至1240℃。热力学计算显示钢中有大量的Mo：C型碳化物生成，计算结果同文献有良好的一致性。提出了质量分数为0．39C-0．6Si-0．4Mn．4．0Cr-2．5Mo．0．9V的热作模具钢具有高热疲劳寿命和抗回火软化能力及高温强度的潜力。

英文摘要：

The chemical composition of hot-work die steel with Nb-microalloyed and high Mo was optimized by using Thermo-calc software and TCFE-3 data base. The influences of the content of elements Cr and Mo on the solution temperature of Mz3C6 type carbide with Cr-rich were discussed, the appropriate mass fi＇action of Cr and Mo is 4.0% and 2.5% respectively. In addition, the influence of Nb on the solution temperature of （V,Nb）C type carbides was discussed too, and the solution temperature was improved fi＇om 1150℃ to 1240℃, when adding content of Nb is 0.03%. The results of thermodynamic calculation indicate that there are large Mo2C type carbides in the steel. The calculation results of Thermo-calc software are agreeable with the literatures. The hot-work die steel which mass fi＇action is 0.39C-0.6Si-0AMn-4.0Cr- 2.5Mo-0.9V has a potential in high thermal fatigue life, against temper softening and high temperature strength.