Characterization and application of tailored hybrid blanks

Abstract

Unlike mechanical joining processes such as clinching or riveting the challenges in connecting steel and aluminum by the conventional welding method are, on one hand, the different physical characteristics such as density, melting temperature, electrical conductivity and thermal expansion. On the other hand due to high heat input, a thick and brittle intermetallic phase seam (IMP) develops in the welded seam. This strongly distinctive phase seam reduces the formability of the welding line and limits the realization in a technical application. Besides through several well known welding tests a new welding technique called Cold Metal Transfer welding (CMT) was introduced by Fronius (Wels, Austria) which lead to an IMP seam of a few micrometers. The main aim of this study is to determine the characterization of the CMT weld and to prove the feasibility to form an aluminum steel hybrid plate into demonstrator components. Results indicate that joining and forming of the aluminum-steel joints with a thickness of 0.8 mm-1.2 mm and 1.75 mm–3.0 mm in a butt-joint configuration is possible. Furthermore formability tests revealed additional difficulties in the forming of steel combined with a nonhardenable aluminum.