Cold forming of Al-5251 and Al-6082 tailored welded blanks manufactured by laser and electron beam welding

This work demonstrates applicability of electron beam welding (EBW) and laser beam welding (LBW) techniques for manufacture of tailored welded blanks (TWBs) from Al-5251 (H22) and Al-6082 (T6) sheets. A combination of dissimilar sheets as well as thicknesses (1.5 mm and 2.5 mm) has been used in addition to a similar combination. An optimal post-weld heat treatment (PWHT) was determined that was effective in relieving stresses and impart adequate ductility in the TWBs allowing cold forming (i.e. stamping), into a cruciform geometry, at ambient temperature. Pull tests revealed marked improvement in elongation for all the welds, including all combinations, after PWHT. Micro-hardness mapping of the weld sections showed transition from a non-uniform to a more uniform distribution via slight increase in hardness of the weld region whilst decrease in the hardness of the parent materials. Non-contact optical measurement using GOM camera showed minimal localised thinning in steep angled areas of the cruciform geometry. The dissimilar LBW TWBs, after PWHT, showed noticeable increase in elongation, homogeneous hardness distribution and slightly refined microstructure in the fusion zone (FZ) compared to their EBW counterparts.