Effect of laser surface melting and subsequent re-aging on microstructure and corrosion behavior of aged S32950 duplex stainless steel

In the present study, the microstructure and corrosion behavior of duplex stainless steel (DSS, S32950) after aging, laser surface melting (LSM) without and with subsequent re-aging were investigated. After LSM, the pitting corrosion resistance of the aged DSS was restored. It is attributed to re-dissolution and removal of M23C6, σ and γ2 phases. The purpose of re-aging is to investigate the phase balance and hence corrosion performance of the laser-melted DSS after subjected to isothermal aging at 800 °C, a condition which might be encountered during application. Results of the present study show that the laser-melted specimens after re-aging is less susceptible to pitting corrosion because the content of γ2 (the anode) is close to that of σ and δ (the cathodes).