Laser-arc welding of duplex stainless steel

Abstract

Duplex stainless steels are used in shipbuilding industry to build chemical and oil tanker vessels. The use of these steels is justified to ensure good corrosion behaviour during lifetime.The main limitation of traditional welding processes when welding duplex stainless steel is that the level of distortion reached is very high, so the global rework time of the construction is increased.Laser hybrid welding process is of great interest for high coefficient of expansion steels like duplex stainless steels as the reduction of the heat input introduced in the material compared to traditional processes would permit an important reduction of the distortion level.However, one of the technical challenges when welding these steels consists of achieving austenite/ferrite grains repartition around 50/50 - as it is in the base material - to keep good corrosion properties. The problem is even more accused when using laser processes as high cooling rates favour the formation of ferrite grains.This paper presents results concerning laser hybrid welding of duplex stainless steel in butt and fillet joint geometries. Experiments will be reported for 12mm thick 2205 stainless steel in similar and dissimilar joints. The welds were characterized by microstructural inspection to determine the ferrite and austenite content.Duplex stainless steels are used in shipbuilding industry to build chemical and oil tanker vessels. The use of these steels is justified to ensure good corrosion behaviour during lifetime.The main limitation of traditional welding processes when welding duplex stainless steel is that the level of distortion reached is very high, so the global rework time of the construction is increased.Laser hybrid welding process is of great interest for high coefficient of expansion steels like duplex stainless steels as the reduction of the heat input introduced in the material compared to traditional processes would permit an important reduction of the distortion level.However, one of the technical challenges when welding these steels consists of achieving austenite/ferrite grains repartition around 50/50 - as it is in the base material - to keep good corrosion properties. The problem is even more accused when using laser processes as high cooling rates favour the formation of ferrite grains.This paper presents resul...