TWI

Friction stir welding (FSW) experiments were undertaken on AA 5083 aluminium alloys to investigate the influence of process parameters (rotational and travel speeds) and preheating temperature on abnormal grain growth after PWHT. The experimental specimens incorporated two different initial tempers, joint configurations, thicknesses and compositions; namely, AA 5083-H18 (tailor welds; 1.5 or 2 mm; Al, 4.56%Mg, 0.7%Mn, 0.12%Cr) and AA 5083-H116 (butt welds; 3.2 mm; Al, 4.1%Mg, 0.54%Mn, 0.22%Fe). FSW was performed on an MTS I-Stir PDS machine under force control mode with cup or scroll shoulders and threaded or Triflute pins. The process parameters varied were rotational speed (H18: 1000-2000 rpm; H116: 700-1500 rpm), travel speed (H18: 50-800 mm/min; H116: 75-800 mm/min) and force (H18: 1.3-4.8 kN; H116: 4-7.8 kN). Electron backscattered diffraction was employed to analyse the grain size and grain boundary orientation. Issues discussed include grain growth dependence on weld temperature and subgrain boundary mobility.

9th International Symposium, 15-17 May 2012, Session 7B: Metallurgy, Paper 01