Numerical and experimental investigation for formability of friction stir welded dissimilar aluminum alloys

Abstract

Automotive manufacturers have been trying to improve fuel efficiency without compromising the structural integrity and one of the ways to resolve the issue is to expand usage of tailor welded blanks (TWBs) in car body structure. Friction stir welding (FSW) is a joining process, which can be well fitted to obtaining aluminum tailored blanks when compared to other conventional joining processes. This paper presents an experimental and numerical study on TWBs produced by FSW with dissimilar aluminum 5083-H32 and 6061-T6 alloy sheets. The quality of the friction stir welded dissimilar joints was evaluated in terms of metallographic observations, hardness studies and tensile tests. Moreover, the local property changes in the weld regions were observed through digital image correlation (DIC) method. Formability of friction stir welded blanks was evaluated in the biaxial stretch forming mode using the limiting dome height (LDH) test. The failure location and the LDH values of the formed blanks were correlated to the hardness and local properties across the welds. The FE simulation of the LDH tests was also conducted incorporating Yld2000-2d anisotropy constitutive properties of the parent metal and further considering the properties of the non-homogeneous welded zone. The Marciniak-Kuczynski model was applied to predict the failure successfully in the FE model, and the results were validated with experimental data.