Abstract
This research work is focused on laser beam and GTA welding processes and their effect on the size and microstructure of the fusion zone then, on the mechanical and corrosion properties of 3 mm thick JIS SUS329J4L duplex stainless steel plates. In contrary to GTA welding, laser beam welding with its lower heat input has resulted in a pronounced decrease in distortion level as well as a remarkable decrease in fusion zone size with much better weld profile.
On the other hand and in comparison with laser beam welding, GTA welding with its higher heat input has resulted in better ferrite/austenite balance in fusion zone due to slower cooling rate. However, laser beam welded joint with its improper ferrite/austenite balance has demonstrated better tensile, impact and corrosion properties due to the remarkable decrease in its fusion zone size. This means that properties of the welded joints are influenced not only by the ferrite/austenite balance but also by the fusion zone size as a function of the welding process. The remarkable reduction of fusion zone size in case of laser welding is more effective for maintaining tensile, impact and corrosion properties, compared to the effect of ferrite/austenite balance that could be pronounced for fusion zones having similar sizes.