Peter Nerman, Johan Andersson, Peter Szakalos

Abstract

The properties of FSW joints in different aluminium alloys has been studied as a part of a joint venture project between ESAB, Husqvarna AB, SCANIA, SAPA, The Swedish Welding Commission, Volvo Cars and JTC-SIMR.

The test material consisted of die cast material, extruded profile and sheet. The joint configurations were I-butt joint, T-joint and overlap joint. The thickness of the test material was in the range of 2-4 mm.

The test joints were evaluated mainly with X-ray and static tensile testing. Fatigue testing at two load levels were performed on the I-butt and overlap joints. With a few exceptions all joints showed good homogeneity and high mechanical strength (both static and dynamic).

It has been shown in this study that overlap joints clearly have much lower fatigue strength than I-butt joints which can be disappointing at the first look. This phenomenon is however, very well known and can be found also for joints performed with other methods such as conventional fusion welding, brazing, adhesive joining etc. The low fatigue strength for overlap joints can be explained mainly by an unfavourable geometry of the joint itself.

It has also been in shown in this study that FSW is very tolerant against a base metal, which contains a lot of pores, and/or have a rough and dirty surface.