Influence of present phases in corrosion and mechanical behavior of UNS S31803 duplex stainless steel welded by conventional short circuit MIG/MAG process

Abstract

Duplex stainless steel (AID) is an alloy that, by allying both good mechanical properties and excellent corrosion resistance properties, comes increasing industrial interest every day. These attractions make it widely used in the most diverse industrial sectors such as pulp and paper industry, nuclear power, processing, oil and gas, among others. Its wide application in several industrial sectors constantly demands that this material is subjected to some welding process. Its high corrosion and mechanical resistance are attributed to balanced microstructure in approximately 50% ferrite and 50% austenite. In the present work, UNS S31803 AID plates were welded in a 45° bevel by conventional short-circuit MIG/MAG process, using three different weld energies, in the range of 0.5–0.8 kJ/mm. The results showed that the effect of the welding energy on the ferrite volumetric fraction was very marked in the heat affected zone (HAZ) and in the weld metal this effect was not so pronounced. The mechanical properties of hardness and corrosion resistance (intergranular corrosion) were evaluated as a function of the welding energy employed. In general, both hardness and intergranular corrosion resistance were not influenced when the various welding conditions were compared. The toughness were evaluated by the crack tip opening displacement technique, compared to the base metal, and the condition 03 (19 V) had the best result.

Keywords

• MIG/MAG process
• Conventional short circuit
• UNS S31803
• Corrosion
• CTOD