A Study on the Implication of Modified Joint Configuration in Friction Stir Welding

Abstract:

The current investigation is a preliminary approach proposing the feasibility of a modified joint configuration namely double-butt-lap (DBL) in the field of friction stir welding (FSW). The main scope of adopting this kind of joint configuration is to essentially eliminate the irregularities in material flow and defects (root gap, kissing bond) that are observed while joining by using the commonly followed simple square butt joint configuration (SSB) technique. Two different geometries of the joint configuration are fabricated on 6 mm thick AA6061-T6 plates. FSW is carried out at a parametric combination of 1100 rpm, 75 mm/min and 1.5° tilt angle. The comparison of the macrographs of DBL with SSB reveals a quite distinct cross-sectional macrostructure of DBL from SSB in terms of material flow in the nugget zone (NZ). Sharp material flow lines without any macro defects are observed in the case of DBL 2. Mechanical test analysis reveals remarkable enhancement in the mechanical properties of some joint configuration of DBL over SSB. The current research work may act as a foundation for future research work in the utility of such configurations in the diverse field of FSW.

Key-words:
Friction stir welding, joint configuration; Macrostructure; Weld defects; Microstructure; Mechanical properties