The effect of phase transformation route on the intergranular corrosion susceptibility of 2205 duplex stainless steel

Two types of austenite morphologies, equiaxed and Widmanstätten, were produced through different phase transformation routes to evaluate the critical factors affecting the intergranular corrosion susceptibility in a 2205 duplex stainless steel. These distinct austenite morphologies behaved quite differently in secondary phase precipitation on exposure to sensitization temperature. Although the Widmanstätten microstructure was found to have a larger degree of coherent ferrite/austenite interface area compared with the equiaxed one, it showed a higher degree of sensitization. It was clarified that, in addition to the ferrite/austenite interface coherency, the extent of an interface area and presence of un-stable ferrite also play prominent roles in intergranular corrosion susceptibility.