本文用定量金相法分析和讨论了奥氏体热作工具钢的晶粒粗化行为.结果表明,在钢中加入Nb可提高MC的稳定性,增加MC的体积分数.Nj/Mn比对晶粒粗化也有较大的影响,随Ni/Mn比的增加,钢中M_(23)C_6和MC质点的体积分数增加。两者均提高晶粒粗化温度。比较了已有的晶粒粗化模型,在晶界面为凸凹不平的曲面前提下,对Gladman模型做了修正,提出了如下的修正Gladman公式: R_0=πr/3f_v(3/2-2/Z) 该公式能较好地预测晶粒的实际尺寸。 In this paper, the quantitative metallurgical analysis and discussion of austenite hot work tool steel grain coarsening behavior.The results show that the addition of Nb in steel can improve the stability of MC, increase the volume fraction of MC.Nj / Mn ratio of grain The roughening also has a greater impact. With the increase of Ni / Mn ratio, the volume fraction of M_ (23) C_6 and MC particles in steel increases. Both increase grain coarsening temperature. The Gladman model is modified based on the existing grain coarsening model. The Gladman’s formula is modified as follows: R_0 = πr / 3f_v (3 / 2-2 / Z ) This formula predicts the actual grain size better.