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

MICROSTRUCTURE CONTROL AND PREDICTION OF GH738 SUPERALLOY DURING HOT DEFORMATIONⅠ.Construction of Microstructure Evolution Model

采用Gleeble-1500热模拟机对GH738镍基高温合金进行了高温热压缩变形实验,分析了该合金在初始晶粒不同的情况下,变形温度1000—1160℃,应变速率0.01—10 s^(-1),工程变形量15%—70%条件下流变应力的变化规律及晶粒组织演化规律;同时研究了变形温度1040—120℃,应变速率0.1—10 s^(-1),变形量15%—50%,保温时间0—45 s条件下该合金的亚动态(静态)再结晶及保温温度980—1140℃,保温时间0—4 h条件下的晶粒长大行为.通过系统的物理热模拟实验,构建了GH738高温合金在热变形过程中的晶粒组织演化模型及应力-应变模型,所建立的GH738高温合金模型与实验结果相比均表现出较高的相关度.

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,metadynamic 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 GH738 superalloy.