Sigma phase precipitation in duplex stainless steel 2205

Sigma phase precipitation is known to embrittle duplex stainless steel. Accordingly, heat treatment and welding must be performed carefully. Nucleation and diffusional growth of sigma phase in the duplex stainless steel 2205 have been analysed in order to ensure the high toughness shown in previous studies for both base and weld material. A quasi-static growth model has been modified in order to take into account interactions with neighbouring particles due to overlapping diffusion fields (soft impingement). The model gives a satisfactory estimate of sigma phase precipitated both during isothermal aging and continuous cooling.