Investigation of microstructural evolution, mechanical and corrosion properties of keyhole tungsten inert gas (K-TIG) welded S32101 duplex stainless steel joints

Keyhole tungsten inert gas welding of 8 mm-thick S32101 duplex stainless steel was conducted. Increasing welding speed refined ferrite and increased austenite fraction. Electron backscatter diffraction revealed dispersed ferrite {100} pole intensity, Kurdjumov–Sachs (K–S)-related multivariant austenite, and non-monotonic Σ3 boundary evolution. The joint achieved the highest mean tensile strength of 684 MPa. The joint showed the lowest kernel average misorientation and the highest mean impact energy. It also exhibited the most favourable pitting and interfacial electrochemical response, with the highest mean breakdown potential versus saturated calomel electrode and charge-transfer resistance.