Effect of the prior cold work on the corrosion resistance of lean duplex stainless steel welded by GMAW process

摘要

>The influence of the prior cold work (0, 10, 30, and 30% thickness reduction) on the microstructure evolution and corrosion resistance of UNS S32304 lean duplex stainless steel (LDSS) welded by gas metal arc welding (GMAW) process was investigated. The cold work promotes flattening of the ferrite and austenite bands, deformed regions in the austenite and increase of the hardness of the material. The welding of the cold‐worked steel generated, besides the typical regions of the welded DSS joints (fusion zone (FZ), heat‐affected zone (HAZ), and base metal zone (BM)), an annealed region around the HAZ, that showed partial recovery of the microstructure and hardness reduction. The HAZ presented excessive ferritization and precipitation of chromium nitrides. The cyclic potentiodynamic polarization tests, in an aqueous solution of 3.5?wt% NaCl at room temperature, showed for the only cold‐worked samples an increase of the pitting corrosion resistance up to a level of 30% thickness reduction and a decrease of the localized corrosion for 50% thickness reduction. The welding of the cold‐worked samples promoted the reduction of pitting corrosion resistance for all levels of thickness reduction evaluated.