Flow instability criteria in processing map of superalloy GH79

GH79合金加工图的流变失稳准则(英文)

Hot compression tests were conducted on a Gleeble-1500D thermal simulating tester.Based on the deformation behavior and microstructural evolution of superalloy GH79,different types of instability criteria of PRASAD,GEGEL,MALAS,MURTY and SEMIATIN were compared,and the physical significance of parameters was analyzed.Meanwhile,the processing maps with different instability criteria were obtained.It is shown that instability did not occur when average power dissipation rate was larger than 60%in the temperature range of 900-930°C and 960-1080°C,corresponding to the strain rate range of 5×10 -4 -1.8×10 -1 s -1 and 5×10 -4 -1.5×10 -1 s -1 ,respectively.The two domains are appropriate for the processing deformation of superalloy GH79.

在Gleeble-1500D热模拟实验机上对GH79合金进行热压缩模拟实验。在对于GH79合金热变形行为及微观组织演变研究的基础上,分析比较Prasad,Gegel,Malas,Murty和Semiatin5种不同失稳判据,并绘制不同失稳判据的热加工图。从不同失稳判据的热加工图中可以看出,在温度900~930°C、应变速率5×10-4~1.8×10-1s-1和温度960~1080°C、应变速率为5×10-4~1.5×10-1s-1的两个范围内该合金的功率耗散率值大于60%,上述两个区域为GH79合金的适合成形区域。