Effect of cold working and isothermal aging on the precipitation of sigma phase in 2205 duplex stainless steel

A comprehensive understanding of the formation of the sigma phase resulting from the eutectoid reaction (delta ->sigma + gamma(2)) is required. The kinetics necessary for the eutectoid reaction are closely related to the amount of plastic deformation in DSS. This work investigates the microstructural evolution of the sigma phase in a 22Cr-5Ni SAF 2205 DSS after subsequent plastic deformation and isothermal aging. The precipitation of the sigma phase resulted from the higher driving force for precipitating intermetallic compounds and the higher diffusion rate of their elements by cold-rolling, as well as the sufficient supply of molybdenum. The maximum amount of sigma phase precipitation remarkably increased with an increasing cold deformation, as compared with the non-cold-rolled materials. (C) 2012 Elsevier Inc. All rights reserved.