Abstract
The presence of secondary austenite (g 2) can influence both the toughness and pitting corrosion susceptibility of duplex stainless steel welds. Samples from conventional (Alloys 2304 and 2205) and 'super-duplex' (Alloy 2507) stainless steels were cycled in a Gleeble 1500ä to simulate the heat-affected zone and to form varying levels g 2. Metallographic characterisation, and toughness and pitting corrosion testing were conducted. It was found that g 2 formation is associated with the dissolution of the chromium nitride (Cr2N) precipitates. Increasing levels of g 2 in the microstructure promoted an improvement in toughness. The pitting corrosion susceptibility of microstructures containing g 2 was intermediate between that of the base metal and microstructures free of g 2 and rich in Cr2N.