Progress in weldability research of duplex stainless steels

Duplex stainless steels (DSSs) show better corrosion resistance with higher strength than traditional austenite stainless steels in many aggressive environments, and can be welded properly with almost every welding processes, if proper heat input is provided. Progresses of research works on weldability of DSSs in recent years are reviewed in this paper. Balance control of ferrite/austenite phases is most important for DSSs welding. The phases balance can be controlled with filler materials, nitrogen addition in shielding gas, heat input, post weld heat treatment, and alternating magnetic field. Too high cooling rate results in not only extra ferrite, but also chromium nitride precipitation. While too low cooling rate or heating repeatedly results in precipitation of secondary austenite and intermetallic compounds. In both situations, mechanical properties and corrosion resistance of the DSS joints deteriorate. Recommended upper and lower limits of heat input and maximum interpass temperature should be observed.