TWI

A modified Gleeble hot torsion test was used to simulate the stir zone microstructures in types 304L and 310 stainless steels obtained during friction stir welding (FSW). A Gleeble 3800 with a torsion mobile conversion unit was used to perform the tests. Testing was performed in a chamber under 56 Pa vacuum. Annular samples were fitted with three type K thermocouples to monitor and collect the thermal data. Specimens were heated at a rate of 40 deg.C/s to a pre-determined peak temperature and held for 5 s and 15 respectively for the 310 and 304L materials before the torsion was applied. A design of experiments was constructed to perform tests over a range of peak temperatures (975-1250 deg.C for 304L and 900-1200 deg.C for 310) and strain rates (250-1150 rpm). Torque data was acquired during testing in order to generate shear stress-strain curves at various strain rates for each peak temperature, from which estimates of material flow stress during FSW could be determined. Microstructures of the samples were examined optically.

8th International Symposium, 18-20 May 2010, Session 5B: Modelling 2, Paper 01