Effectiveness of the indigenously developed static shoulder friction stir welding tool on textural characteristics of Al6061 alloy – A comparison to external cooling media friction stir welds

Abstract

• A novel static shoulder friction stir welding tool has been developed. • Developed tool is both rotating and non-rotating shoulder tool without sub shoulder. • The tool's effectiveness in lowering HAZ width is compared to cooling media FSW. • Texture components reflect different recrystallization types for both processes. A novel in-house friction stir welding (FSW) tool that can act as both static shoulder and rotating shoulder was developed. In this article, two Al6061 plates were subjected to static shoulder FSW (SSFSW) and external cooling media FSW (ECFSW) using the indigenously developed tool. To investigate the effectiveness of the developed tool, microstructural and textural aspects of SSFSW were compared with that of ECFSW. Electron backscattered diffraction results revealed a significant reduction in the percentage of low angle grain boundaries from 61.4% (base material) to 28.4 % (ECFSW), and 8.6 % (SSFSW). The evolved texture components after FSW are completely different from base material and the overall texture strength increased after FSW. Pole figures of SSFSW revealed the presence of A, B components with maximum intensity of 10.489 while in ECFSW, presence of A 2 *, B ¯ components with maximum intensity of 7.913 were observed. Oriental distribution function showed strong orientations of {0 3 1} 〈2 1 3〉, {0 0 1} 〈1 1 0〉,{1 1 2} 〈0 1 1〉, {1 2 3} 〈6 3 4〉 and moderate Cube components in case of ECFSW. In the instance of SSFSW, there was dominant presence of γ fibre. Correlation between the microstructure and texture has revealed the occurrence of meta-dynamic recrystallization in ECFSW and continuous dynamic recrystallization in SSFSW.