Deep drawing of Ir-0.3%W alloys

Cold-worked 0.65 mm thick Ir-0.3%W alloy sheet was deep drawn 45% into 28 mm diameter cups at temperatures below 600 °C using a single draw process, BN powder for lubrication, and electrically heated H-12 steel tooling. A ductile-brittle transition temperature was observed near 550 °C. Below this temperature failures occurred at the bend radius. The failure mechanism can be understood in terms of the tensile properties of the alloy. The frequency of cracks caused by tensile stress decreased with increasing drawing temperature above the ductile/brittle transition temperature. The strain ratio r was determined to be 0.6 for alloy sheets tested at 500 °C. © 1994.