Calibration of the Elasto-Plastic Properties of Friction Stir Welded Blanks in Aluminum Alloy AA6082

Abstract

In recent years remarkable efforts have been devoted to the study of the formability of tailored blanks processed by friction stir welding (FSW) by means of numerical and experimental approaches. This study aims to perform an inverse analysis to calibrate the constitutive law of FSW blanks produced with different parameters. The evaluated mechanical behavior will be employed in future studies to investigate the formability of such elements by single point incremental forming. This study analyzes friction stir welded blanks in aluminum alloy AA6082-T6 produced with different advancing velocities and tool rotational speeds. Coupons for tensile testing have been cut and collected from the FSW blanks. The longitudinal dimension of the coupons was perpendicular to the tool advancing direction, with the welding centerline located at the middle point of the coupon. From the same welded blanks further coupons have been collected to conduct microhardness testing of the cross-section in the welding zone. Data from digital image correlation (DIC) have been adopted to detect the zones of local variation of the mechanical properties related to the peculiar microstructure determined by friction stir welding. In particular, the data were used as input to feed an iterative numerical routine to calibrate the constitutive law variable as a function of the distance from the welding centerline.