Laser welding and surface treatment of a 22Cr–5Ni–3Mo duplex stainless steel

A study on improved laser weldability of a type 22Cr–5Ni–3Mo (UNS S32205) duplex steel is presented. To counterbalance the excess of δ-ferrite formed in the as welded joint, samples were surface treated by using the same laser source adopted during welding. An analytical description of the thermal field generated during welding and surface treatment by a CO2 laser source was developed and allowed optimal process parameters to be stated for the experimental investigation. Experimental results demonstrated that both microstructure and elemental distribution between δ-ferrite and γ-austenite could be restored to values close to those of the solution treated parent metal. The capability of achieving a good structural control of the weld bead microstructure by an optimized selection of laser parameters for the post-weld surface treatment was thus demonstrated.