Effect of the micro-plasma arc welding technique on the microstructure and pitting corrosion of AISI 316L stainless steels in heavy LiBr brines

The effects of the micro-plasma arc welding technique on the microstructure and pitting corrosion of different zones of an AISI 316L stainless steel were studied using different microscopy and electrochemical techniques. Galvanodynamic measurements and laser scanning confocal microscope were used to evaluate the corrosion evolution in situ. Results show, in general, the worst corrosion behaviour for the heat affected zone. Furthermore, there is a relation between the effects of the micro-plasma arc welding process on the materials microstructure and their pitting corrosion resistance. The weld zone was always in the cathodic position of the possible galvanic pairs.

► Micro-plasma arc welding modifies mechanical and corrosion properties of the alloy.
► The base zone of the welded alloy presents the best corrosion behaviour.
► The pair which presents the worst galvanic behaviour is the base zone/weld zone.
► A relation between pitting corrosion and microstructure of the materials was found.
► A multicorrosion attack is only shown in the weld zone.