Influence of friction stir welding parameters on mechanical and electrochemical performance of EN AW-6082-T651 alloy butt joints

Abstract This study investigates the influence of friction stir welding parameters, specifically tool rotational speed and linear speed, on the electrochemical and mechanical properties of EN AW-6082-T651 butt joints. The research encompassed microstructural analysis, surface roughness measurements, potentiodynamic corrosion tests, hardness profile measurement, and static tensile testing. Results revealed that decreasing the linear speed or increasing the rotational speed during welding intensified heat input, leading to grain growth in the weld nugget zone. The smallest grain size of 3.46 ± 1.11 µm was achieved at 1000 rpm and 250 mm/min. Surface roughness was minimized at 1250 rpm and 200 mm/min, as excessive tool feed caused irregularities. Corrosion resistance improved compared to the parent material, attributed to fine-grained structures promoting compact passive layer formation. Hardness profiling indicated the lowest values in the heat-affected zone, particularly for joints produced at 1250 rpm and 200 mm/min due to the highest heat input and precipitate dissolution. Tensile testing confirmed fracture locations in the heat-affected zone, with maximum tensile strength reaching 69% of the base material and elongation approximately 30%.