POSSIBILITY OF GRAIN-REFINEMENT FOR SUPERPLASTICITY OF A MG-AL-ZN ALLOY BY PRE-DEFORMATION

For a commercial Mg-Al-Zn alloy sheet, tensile tests are carried out under various strains, strain rates and temperatures to investigate the possibility of grain refinement by dynamic recrystallization during pre-deformation. It is found from the microstructural observations that relatively fine grains of 10-mu-m or so, in diameter are attained under the conditions of 250-degrees-C and 8.3 x 10(-4) s-1. The specimen pre-strained under this condition also exhibits a fairly good superplasticity of total elongation beyond 300%.