Study of meta-dynamic recrystallization behavior of GH5188 superalloy

Abstract

Cobalt-based superalloys have good service performance in environments where nickel-based superalloys cannot work. A number of the studies focused on mechanical properties, microstructure evolution and hot deformation characteristics, but studies of meta-dynamic 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.

Keywords

• GH5188 superalloy
• Hot compression
• Meta-dynamic recrystallization
• High-temperature deformation