FSW of aluminum AA5754 to steel DX54 with innovative overlap joint

Abstract

An innovative overlap joint concept was tested to evaluate the quality improvement of welds between aluminum alloy AA5754-H22 (2 mm) and steel DX54 (1.5 mm). The innovation is a wave-shaped interface produced on the steel being directly processed by the tip of the probe, generating localized heat, extensive chemically active surfaces, and additional mechanical interlocking. Welds with different parameters were evaluated by metallographic analysis and mechanical tests. The best set of parameters was then implemented in a conventional overlap joint, plus in two-and three-passes welding, with the innovative overlap joint concept, to evaluate the effect on microstructure and mechanical efficiency. With a single-pass weld, the new concept presented lower strength in tensile shear tests, but higher strength in peeling tests. The main mechanism governing this behavior was the reduction of effective thickness in the aluminum alloy sheet, due to the flow of steel into the aluminum alloy. The characterization and distribution of the intermetallic compounds were evaluated via SEM-EDX. The two-passes weld resulted in the best strength values in tensile shear tests, reaching about 50% of the ultimate tensile strength of the aluminum alloy base material.

Friction Stir Welding of Dissimilar Butt Joints with Novel Joint Geometry

“…The probe filled the aluminum alloy in the cavities of wave shaped geometry resulting in mechanical clamping. It was reported by Sorger et al [14] that the joint strength of about 50% of the ultimate tensile strength of the base aluminum alloy was achieved.…”

A review on friction-based joining of dissimilar aluminum–steel joints

“…71 Wave shaped tool pin base has improved steel flow in the Al material with two passes of processing. 117 However, obtained tensile strength from wave shaped tool pin base is not up to the mark relative to the conventional method. Cutting edge type of the tool is adopted to obtain enhanced distribution of steel particles in Al that in turn resulted into higher strength than the Al base material.…”

“…The FSW process is expanded with different approaches such as application of Zn interlayer between Al and steel base material, 71 scroll tool shoulder without pin, 91 wave shape tool pin base for lap joint configurations, 117 kneed type butt joint configuration, 124 and cutting edge type tool pin. 80 It is recommended to use third material layer as the interlayer between dissimilar materials in the case of FSW.…”

Multiphysical characterization of FSW of aluminum electrical busbars with copper ends

“…This same phenomenon is later emphasized in this paper, based on the results from the monitoring of the temperatures during the FSW of the Al-Cu joints. Good quality FSW bimetallic joints are now feasible for Al to steel [5][6][7] and Al to Cu [8]. Avoiding common problems associated with fusion welding of dissimilar metals, such as mismatch of fusion temperature, formation of extensive brittle intermetallic compounds (IMC's), gas solubility, and high distortion, and residual stress [2], the FSW opened up new possibilities in the design optimization and manufacturing of various products.…”