On characterisation of local stress-strain properties in friction stir welded aluminium AA 5083 sheets using micro-tensile specimen testing and instrumented indentation technique

Stress-strain property variations in welded joints are frequently characterized by determining local stress-strain curves across the joint. A commonly and widely accepted method is testing of micro-tensile specimens where the specimens have to be mechanically extracted form the joint and subsequently tested and analysed similar to that of a conventional tensile tests. A recently developed procedure for the determination of local stress-strain properties is based on instrumented indentation testing where the force-depth curves are analysed via artificial neural networks in order to derive local stress-strain curves. In order to verify this new method on welded joints, this method has been applied to a friction stir weld in 3 mm thick aluminium AA 5083 sheet material. It turned out that the local stress-strain curves derived by instrumented indentation tests and neural networks are compatible with that obtained from micro-tensile testing. Further on, the article gives advises on a proper tests specimen preparation as well as on the treatment of possible residual stresses.