TWI

With regard to the fabrication of closure welds for used fuel containers, a series of experiments was undertaken to demonstrate the feasibility of creating defect-free partial penetration welds by friction stir welding (FSW) in A516 Grade 70 steel (0.15%C, 1.16%Mn, 0.03%Cr, 0.03%Ni, 0.07%Cu) plates and the microstructure and mechanical properties of the weld zone were investigated. The FSW tool was a convex scroll shoulder with a step spiral pin and three flats at the pin tip and was made from Q70 material (70% cubic BN-30%WRe). Welding was performed at a rotational rate of 150 rpm, travel speeds of 0.42-1.27 mm/s and tool temperatures in the range 650-820 deg.C. Process parameter maps were studied for bead-on-plate and butt welds. Weld zone microstructures were observed by optical microscopy and SEM. Mechanical properties were characterised by Vickers hardness measurements as well as tensile and Charpy impact tests. Residual stresses were determined by the ring core method.

10th International Symposium, 20-22 May 2014, Session 2A: Steel I, Paper 04