终锻温度对GH4738高温合金热变形行为的影响

采用非持续加热方式设计非等温热模拟压缩实验,模拟不同终锻温度条件下GH4738高温合金的热变形行为,并结合组织观察分析终锻温度对GH4738合金组织均匀性以及后续热处理过程组织遗传性的影响规律。研究结果表明,在相同始锻温度条件下,终锻温度过低会抑制GH4738合金热变形过程中动态再结晶的发生,从组织上表现为再结晶程度较低,从流变曲线上表现为变形抗力明显升高;并且由于终锻温度过低所导致的不充分再结晶组织,在后续热处理过程中易发展为混晶组织,从而影响合金的组织均匀性。为保证锻件组织均匀性,在制备过程中应合理控制终锻温度。

The Effect of Final Forging Temperature on Hot Deformation Behavior of GH4738 Superalloy

In present work, a non-isothermal simulated hot compression test is designed to investigate the effect of final forging temperature on hot deformation behavior of GH4738 superalloy. Microstructure observation is carried out to explore the effect of final forging temperature on homogeneity of microstructure and microstructure heredity in following heat treatment process. The results show that in the condition of same initial forging temperature, the dynamic recrystallization of GH4738 superalloy will be inhibited when the final forging temperature is too low. The fraction of dynamic recrystallization is relatively low and the flow stress keeps increasing during hot compression. The less developed dynamic recrystallization microstructure tends to develop into mischcrystal structure in the following heat treatment process and can influence the homogeneity of microstructure. Hence, the final forging temperature should be rational controlled to improve the microstructure homogeneity of forgings during hot deformation.