Superplastic behavior of the Sn-Pb eutectic in the as-worked state

Superplastic behavior of the Sn-Pb eutectic was studied in the as-worked state by mechanically working the cast material to varying degrees. The flow behavior was explored in the temperature range of 298 to 443 K and metallographic observations of longitudinal and transverse sections were made. The microstructure was inhomogeneous for low degrees of working, while at high reductions the grains were nonequiaxed. There was strain softening or hardening up to some strain depending on the test conditions. The grains became more equiaxed and coarser in size with increasing deformation. Due to these changes in microstructure and the nonunique stress-strain rate relation, the as-worked material is not suitable from the viewpoint of assessing the mechanisms of superplastic flow based on steady state. Strain dependency of flow stress was also observed in specimens specially processed to obtain equiaxed grains in the as-worked state. formerly a graduate student at Indian Institute of Technology, Kanpur, India.