EFFECT OF PREDEFORMATION AND SEMISOLID ISOTHERMAL TREATMENT TIME ON THE GLOBULAR GRAINS IN MRI230 ALLOY DURING SIMA PROCESS

摘要

The effect of predeformation and holding time in the semisolid temperature has been investigated in MRI230 alloy through SIMA process. The following results can be concluded: ⅰ. 4% deformation was not efficient to promote grain globularization, showing the worst shape factor, 0.43 for 20 min holding time and the biggest average grain size, 582um for 60 min SSIT time. ⅱ. 7% deformation was able to promote homogeneous globular microstructure with the best shape factor 0.85 and average grain size 112 urn for 60 min SSIT time.