Study of damage initiation and fracture in aluminum tailor welded blanks made via different welding techniques

The present paper addresses microstructural evaluation of failure in multi-gauge aluminum alloy tailor welded blanks (TWBs), welded using non-vacuum electron beam and neodymium:yttrium–aluminum–garnet laser techniques. The limiting dome height test is used to evaluate formability of the TWBs. Three gauge combinations utilizing AA5754 sheets are considered (2 to 1 mm, 1.6 to 1 mm and 2 to 1.6 mm). Different weld orientations have been considered: transverse and longitudinal. In general, TWBs show two different types of fracture: weld failure and failure of the thinner aluminum sheet. Interaction of several factors determines the type of failure occurring in a TWB specimen. These factors are weld orientation, morphology and distribution of weld defects as well as the degree of constraint imposed by the thicker sheet on the thin sheet. The last factor usually depends on the difference in thickness of the sheets and is represented here in terms of gauge ratio.