Effect of welding parameters on mechanical and microstructural properties of AL 2024 joints produced by friction stir welding

Results of Friction Stir Welding (FSW) of aluminium 2024 are presented in this paper. Investigations were conducted on the welding machine, built on the base of the conventional, vertical milling machine. The quality assessment of joints was done on the grounds of the visual inspection, tensile and fatigue tests, the analysis of the welds structure and hardness. Heat treatment was not done after the welding process. The goal of the research was to know the relationship between welding parameters and mechanical and microstructural properties of 2024joints. Results indicate that weldability of aluminium alloys of Al 2024 4 mm in thickness with FSW method is good. Properties ofjoints with the FSW method on the milling machine eąuipped with LOWSTIR device fulfil requirements of this kind of joints. The structure is correct and the tensile properties are higher than properties of arc welded joints. With wide range of welding parameters the high quality of joint is possible. Joints welded with the different tools and in different conditions had characteristic shape of nugget, heat affected zone and thermo-mechanically affected zone. The kind of tool is not affected on properties of FSW joint at the same parameters. The proper quality at four different kind of tool is possible to achieve. Fatigue properties of the FSW joints made in correct way are very high, higher than properties of arc welded joints. Hardness profile of welds had characteristic run, typical for joints welded with the FSW method. The LOWSTIR device is not getting worse the quality of FSW joints.