GH738高温合金热加工行为

Hot Deformation Behaviour of Superalloy GH738

摘要:

采用Gleeble-1500热模拟机对GH738镍基高温合金进行高温热压缩变形实验，分析该合金在变形温度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。确定GH738合金热变形方程，建立热加工图(Processing map)，并通过组织观察对热加工图进行解释。GH738合金热变形激活能Q为499 kJ/mol；热加工图随不同变形量而变化，在应变速率较低，温度较高的状态下，能量耗散效率较高。综合应变量为0.2，0.4，0.6和0.8应变量下的热加工图，确立了该合金最佳热加工“安全通道”，为GH738高温合金热加工工艺优化提供理论依据。

Abstract:

Hot deformation behavior of GH738 superalloy was studied in the temperature range of 1000~1160 oC, strain rate range of 0.01 ~10 s-1 and engineering strain range 15%~70% by the Gleeble-1500 simulator. The hot deformation equation was determined to characterize the dependence of peak stress on the temperature and strain rate. Processing maps for hot working were established on the basis of the variations of efficiency of power dissipation with temperature and strain rate, and interpreted according to the microstructure observation. The apparent activation energy Q of GH738 superalloy is about 499 kJ/mol. The maps obtained in true strain range from 0.2 to 0.8 are essentially different, and the efficiency of power dissipation increases gradually with the increase of temperature and the decrease of strain rate. An optimum zone named safe area is obtained for GH738 alloy deformation. The above results can be used as a reference for hot working of GH738 superalloy.