A study of duplex stainless steels aged at 325°C under applied tensile load

Paper in proceeding, 2011

Duplex stainless steels (DSS) are widely used due to their good combination of corrosion resistance and mechanical properties. The embrittlement caused by phase separation of ferrite in DSS, however, limits the maximum service temperature. Since weldments have been considered most sensitive it has been speculated whether weld residual stresses contribute to the kinetics of phase separation. A mechanistic study was performed on commercial DSS materials of different alloying levels. Specimens were aged under load and the mechanical properties in terms of hardness and impact toughness were determined. Also weld structures and simulated HAZ structures were tested. Differences in response were observed for the different microstructures, which were characterized by EBSD and TEM. The decomposition was characterized using atom probe tomography and the results seem to support the effect of stress on kinetics.