TWI Digital Library

Optical microscopy, SEM and electron backscattering diffraction techniques were employed to investigate the microstructural evolution and solid-state phase transformations during friction stir spot welding (FSSW: also known as friction spot joining) of DP-590 dual-phase steel (0.06%C, 0.49%Si, 1.23%Mn). FSSW experiments were performed at a rotational speed of 3000 rpm using a Si₃N₄ threaded tool. Three distinct microstructural regions were identified and their microhardness and martensite morphology characteristics were examined. Issues discussed include the orientation relationships governing the austenite-to-martensite phase transformation and plastic deformation in the austenite phase.

7th International Symposium, 20-22 May 2008, 7A: Spot 2 (Mg/Fe/Al), Paper 04