Effect of Weld Length on Strength, Fatigue Behaviour and Microstructure of Intersecting Stitch-Friction Stir Welded AA 6016-T4 Sheets

Abstract

Friction stir welding is a promising joining process for boosting lightweight construction in the industrial and automotive sector by enabling the weldability of high-strength aluminum alloys. However, the high process forces usually result in large and heavy equipment for this joining method, which conflicts with flexible application. In order to circumvent this issue, a friction stir welding gun has been developed which is capable of producing short stitch welds—either stand-alone as an alternative to spot welds or merging into each other appearing like a conventional friction stir weld. In this study, the influence of the stitch seam length on the strength properties of intersecting friction stir welds is investigated, and the weld is characterized. For this purpose, EN AW-6016 T4 sheets were welded in butt joint configuration with varying stitch lengths between 2 and 15 mm. Both the static and dynamic strength properties were investigated, and hardness and temperature measurements were carried out. The results show a scalability of the tensile strength as well as the fatigue strength over the stitch seam length, while the substitute proof strength is not affected. Hereby, the tensile strength reached up 80% of the base materials tensile strength with the chosen parameter setup. Likewise, the stitch weld length influences the hardness characteristics of the welds in the transition area.

The Effect of Cooling Temperature on Microstructure and Mechanical Properties of Al 6061-T6 Aluminum Alloy during Submerged Friction Stir Welding

“…Khalafe et al [23] systematically reviewed 150 research studies and highlighted FSW parameters and their influence on the quality of the FSW joints for the aluminum alloys in similar and dissimilar material systems. Walz et al [24] investigated the effect of the stitch seam length on the strength properties of intersecting friction stir welds of EN AW-6016 T4 sheets in a butt configuration. They reported an increase in tensile and fatigue strength over the stitch seam length.…”