Embrittlement and corrosion decay of a cast duplex stainless steel

Abstract

Duplex stainless steels (DSS) are Fe-Cr-Ni-Mo alloys, with low carbon content, which have a favorable combination of mechanical properties and corrosion resistance. These characteristics are mainly attributed to a dual phase and refined microstructure, typical of these alloys, consisting of similar amounts of ferrite and austenite. For this reason, DSS are widely used in various segments of industry, especially in offshore applications. However, DSS components may have a decrease of their properties when they are exposed high temperatures, often due to incorrect manufacturing processes. Intermetallic phases may precipitate causing embrittlement and corrosion resistance decrease. This work presents the effects of short time aging at 475 °C on the mechanical properties and localized corrosion resistance of a cast DSS. The results show that mechanical properties, such as toughness and hardness, are more susceptible to aging, having already been affected during the first 4 hours of heat treatment, while the corrosion was affected in 12 h of aging.