A study on the effect of cooling on microstructure and mechanical properties of friction stir-welded AA5086 aluminum butt and lap joints

摘要

In this paper, the effect of water cooling on mechanical properties and microstructure of AA5086 aluminum joints during friction stir welding is investigated. For doing so, the mechanical and microstructural behavior of samples welded both in air and in water was analyzed. Tests were performed involving both butt and lap welds and the results were compared. The effect of rotational speed at constant feed rate of 50mm/min and changing rotational speed ranging from 250 to 1250r/min was investigated. The results showed a significant change in the tensile behavior of the butt-welded specimens due to water cooling. In addition, welding was performed at constant spindle speed of 800r/min and various traverse speeds (25mm/min to 80mm/min) to determine the effect of feed rate. The strength increases at first, but then decreases dramatically along with the feed rate which is due to the occurrence of a groove defect. Results showed some generally positive impacts of water cooling which are discussed in terms of tensile results, hardness distributions and microstructure analysis.