Technology of friction stir welding of aluminium alloy 6082 T‐joints and their behaviour under static and dynamic loads

Abstract

The paper deals with an investigation of technological possibilities to produce T‐joints of Al 6082 by friction stir welding technique and mechanical properties of the joints. It was indicated the importance of preparation proper welding stand by showing joints quality, presented on macrostructures, obtained with and without specially designed equipment for welding T‐joints. Different ways of base metal preparation prior to welding (T‐joints welded as two pieces and as three pieces), as well as two various shapes of steel dies directly forming the shape of tee connections, were used in experiments. It was shown how welding conditions influence structure and static properties of friction stir welding joints. Results show that for specified tool speeds significant imperfections, like voids, were formed. The best experimentally defined welding parameters, ensures lack of voids, were used to produce test joints for fatigue test. For the tested friction stir welding T‐joints the fatigue category FAT were determined and compared to FAT categories of equivalent T‐joints welded by conventional fusion welding. The study reveals also metallographic macroscopic and microscopic examination results, indicated typical imperfections arising during friction stir welding process of T‐joints, as well as results of hardness measurement of joints cross section.