MICROSTRUCTURE EVOLUTION OF AL 1060 UNDER DOUBLE-SIDED PRESSURE DEFORMATION CONDITION DURING VISCOUS PRESSURE BULGING (VPB) TEST

摘要

A viscous pressure bulging test (VPB) of an aluminum sheet with stainless steel overlapped outside is developed as a novel method to investigate the effect of the compressive normal stress on the sheet metal formability. Microstructure evolution of aluminum sheet metal under double-sided pressure is studied by optical microscope (OM) and transmission electron microscopy (TEM). It is found that the limiting dome height (LDH) of the double-sided pressure bulging specimen is increased by 57% compared with the single-sided pressure bulging specimen. The substructure of the double-sided pressure bulging specimen at large strain (ε_(eq) =0.803) appears to be equiaxed and has undergone a recovery process. The results indicate that the normal pressure is helpful in improving the deformed microstructure and formability of aluminum sheet metal.