Effect of repeated TIG welding cycles on microstructure evolution and pitting corrosion behavior of UNS 32760 super duplex stainless steel

Abstract

Microstructure evolution and pitting corrosion behavior in repeated TIG welding cycles of UNS32760 super duplex stainless steel were studied. The microstructural evolution was observed through optical electron microscope. Meanwhile, pitting corrosion was investigated by means of potentiodynamic polarization and gravimetric test. The specimens were evaluated to simulate repeated welding cycles of original weld, Repair-1 (R1), Repair-2 (R2) and Repair-3 (R3) respectively. The result show that the chromium nitride precipitates starts appear in heat-affected zone R-2 welding cycles which followed by the growth of metastable pits.