GH738高温合金热变形过程显微组织控制与预测 I．组织演化模型的构建

The hot deformation behavior of GH738 superalloy with different initial grain sizes was studied using hot compression experiments via Gleeble-1500. Correlations between flow stress, process parameters and microstructure evolution were characterized in the temperature range of 1000— 1160 , strain rate range of 0.01—10 s −1 and engineering strain range of 15%—70%. Besides, meta- dynamic recrystallization and static recrystallization were studied in the temperature range of 1040— 1120 , strain rate range of 0.1—10 s −1 and engineering strain range of 15%—50% with soaking time for 0—45 s; grain growth behavior was researched in the temperature range 980—1140 with soaking time for 0—4 h. The results show that recrystallization behavior of GH738 superalloy was significantly affected by initial grain size, deformation temperature, strain and strain rate. Thermo- mechanical behavior and microstructural evolution models were constructed based on the systematical investigation of dynamic recrystallization, meta-dynamic recrystallization, static recrystallization and grain growth. The analyses indicate that these models shows a high correlation with actual results of