Study of meta-dynamic recrystallization behavior of GH5188 superalloy

Cobalt-based superalloys have good service performance in environments where nickelbased superalloys cannot work. A number of the studies focused on mechanical properties, microstructure evolution and hot deformation characteristics, but studies of metadynamic recrystallization (MDRX) behavior remain lacking. The MDRX behavior of GH5188 superalloy was investigated using two-stage hot compression tests. The kinetic model and grain size model were built to better describe the MDRX process. The good agreement between the predicted values and experimental values was verified. The effects of holding time, temperature, strain rate and intervals time on MDRX microstructure evolution were analyzed and discussed. The results show that by descending order of correlation was: intervals time, holding time, temperature and strain rate. The MDRX fraction and grain size increase with the increase of holding time, temperature, strain rate and intervals time. At low temperatures, MDRX grains grew up in the form of bowed grain boundaries. At high temperatures, the growth of MDRX grains was often accompanied by the generation of twinning bands. Twins were formed in the process of grain growth. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).