| Because of the unstable quality of the supplied products for Nimonic 80A used for blades materials, and the great influence of grain structure on the creep resistance of materials, analysis of microstructure evolution during processings such as forging and heat treatment was conducted. Through this study, the mechanisms of complex grain size distribution and its related factors were concluded.In this paper, simulation of the processing such as forging and heat treatment were done to examine its influence on the grain structure.Use Gleeble 3500 to simulate the process of forging. Temperature of hot deformation is from 1000℃to 1150℃, and the true strain is from 0.22 to 1.61, with constant strain rate of 1s-1. Investigate the mechanism of dynamic recrystallization (DRX) during hot deformation with optical microscopy (OM) and electron backScatter diffraction (EBSD) in detail; Study the influence of hot-deformed condition on the grain size distribution systematically with EBSD, Image-Pro Plus and Origin. Besides, the behavior of twinning boundary during hot deformation was also studied with EBSD. In the end, the relationship between grain structure and condition of hot deformation was obtained.Study the microstructure evolution after different heat treatments, with temperatures from 1060℃to 1150℃, time from 2 minutes to 60 minutes and then water cooled. Through OM, abnormal grain growth (AGG) was found in the condition 1080℃, 60minutes, 1100℃, 8 minutes and 1120℃, 4 minutes; while at 1060℃, there is no AGG after 60 minutes; grains have shown apparent growth after 2 minutes at 1150℃. Meanwhile, investigation of carbides distribution with the variation of time at 1120℃with backscatter electron image (BSE) was conducted to study its influence on AGG. |
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