The influence of welding process on size and microstructure of fusion zone then, on mechanical and corrosion properties of duplex stainless steel plates with 3 mm thickness was clarified. In this respect, autogenous butt weld joints were made using both GTA and carbon dioxide laser with a maximum output of 5 kW in the continuous wave mode.

The results achieved in this investigation disclosed that welding process play an important role in obtaining satisfactory weld joint properties. In comparison with GTA, laser beam has produced weld joint with a remarkable decrease in fusion zone size and acceptable weld profile.

The ferrite/austenite balance of both weld and HAZ zones is remarkably influenced by heat input which is a function of welding process. In comparison with laser beam welding, GTA welding has resulted in ferrite/austenite balance close to that of base metal due to the high heat input. However, ferrite/austenite balance of laser welds was improved by solution annealing of welded joints.

Ferrite/austenite balance has little influence on yield and tensile strength of welded joints. However, it has a marked influence on both ductility and pitting corrosion resistance.