TWI

An experimental investigation was undertaken to examine the effect of a TIG welding torch assisted heating source on the microstructure, mechanical properties and fracture mechanism of dissimilar Cu/austenitic stainless steel butt joints fabricated by friction stir welding (FSW). Welding experiments were conducted at a feed rate of 31.5 mm/min, tool rotational speed of 1500 rpm and tilt angle of 2 deg. Additional cooling comprised compressed air or water cooling at the trailing side of the tool and additional TIG heating (current 20-60 A) at the leading side of the tool. Microstructures of parent metal, HAZ and thermomechanically affected zone as well as tensile fracture surfaces were observed by optical microscopy and SEM. Mechanical properties were characterised by Vickers microhardness measurements and tensile tests. The occurrence of ductile fracture in the case of assisted heating and brittle fracture with additional cooling is discussed.

11th International Symposium, 17-19 May 2016, Session 7B: Dissimilar, Paper 02