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通过金相实验法研究了齿轮钢SAE8620H在950~1150℃、保温时间0~80 min之间奥氏体晶粒的长大规律,并利用Beck、Hillert、Sellars数学模型建立了其奥氏体晶粒长大模型。结果表明:SAE8620H钢奥氏体晶粒尺寸随温度升高逐渐增大,随保温时间延长而增大,在1050℃以上晶粒粗化。通过对3种晶粒长大模型的对比分析,Sellars模型对SAE8620H齿轮钢奥氏体晶粒长大预测精度最高,其晶粒长大激活能为Q=376869.353 J/mol,与根据成分计算出的Q值误差很小,建立了其奥氏体晶粒长大Sellars模型。
The growth regularity of austenite grains of gear steel SAE8620H at 950 ~ 1150 ℃ and holding time of 0 ~ 80 min was studied by metallographic method. The austenite grains were established by the Beck, Hillert and Sellars mathematical models. Growing grain model. The results show that the grain size of austenite in SAE8620H steel increases with increasing temperature, increases with the holding time, and coarsens the grain above 1050 ℃. Based on the comparison of the three grain growth models, the Sellars model has the highest prediction accuracy for the austenite grain growth of SAE8620H gear steel. The activation energy of grain growth is Q = 376869.353 J / mol, which is calculated according to the composition The error of Q value is very small, and its Sellars model of austenite grain growth has been established.