TWI

Bead-on-plate welds were fabricated in S31254 superaustenitic stainless steel (19.82%Cr, 17.78%Ni, 6.13%Mo) plates (thickness 6 mm) using friction stir welding (FSW) and their microstructure and texture evolution were studied by high resolution electron backscattering diffraction (EBSD). FSW was conducted with a polycrystalline cubic BN welding tool, consisting of a convex scrolled shoulder and a step-spiral pin, at tool rotational speeds of 400 or 800 rpm and a travel speed of 30 mm/min. Welded joints were sectioned perpendicular to the welding direction for microstructural examination. EBSD analysis was undertaken in an Hitachi S-4300SE field emission SEM. Grain size measurements were made on EBSD maps by the grain reconstruction method. Issues discussed include microstructure distribution and texture in the stir zone and the contribution of discontinuous recrystallisation to grain structure formation.

9th International Symposium, 15-17 May 2012, Session 7B: Metallurgy, Paper 03