Numerical and experimental investigation of probeless friction stir spot welding of a multilayer aluminium alloy compound

Abstract

This paper presents the experimental and numerical results of the influence of dwell time (30, 60, 90 s), down force (2450, 4900, 7350 N), and rotational speed (1000, 1500, 2000 RPM) on microstructure, microhardness, and material flow during solid-state welding. Probeless friction stir spot welding (P-FSSW) with a flat tool shoulder was assisted to form a metal compound of AA2024, AA6082, and AA5754 aluminium plates with different thicknesses in lap configuration. The analysis of the experimental data and numerical results showed that down force had a significant influence on the material flow and the quality of the welds. High friction energy, and subsequent intensive material flow, promoted the vortexes formation, which improve metals mixing and grain refinements.

KEYWORDS:

• Probeless friction stir spot welding
• aluminium alloys
• numerical analysis
• material flow
• microstructure
• multilayer metal compound
• microhardness

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was partly supported by the project ‘Research for Innovation (REFIN)’ POR PUGLIA FESR-FSE 2014/2020. (REFIN)' POR PUGLIA FESR-FSE 2014/2020. CUP D94I20000410008 and partially by the ‘World-class Science Center’ with program: Advanced digital technologies Center' with program: Advanced digital technologies [grant agreement no. 075-15-2020-903].