Tensile strength analysis of friction stir welded joints of AlMg6 obtained using additional heating of the parts

Abstract

During friction stir welding a structure of a material in the welding zone undergoes significant changes: recrystallization occurs with the formation of three different zones: the weld nugget zone, thermomechanically affected zone and heat affected zone. It is known that a significant change in microstructure that observes on the boundaries between the above mentioned zones creates dangerous areas in the weld, and when testing specimens the fracture mostly occurs in these areas. In this study, the tensile strength analysis of friction stir welded joints of aluminum plates of AlMg6 of 3.85 mm thickness obtained using additional heating of the parts was conducted. The macrostructure of the welds was investigated; the fracture line of specimens is shown; the reasons that lead to decrease in durability of welds are identified. The tensile strength of welded joints amounted to 85-93% of the tensile strength of the base metal.