The development of techniques to improve the welding of super duplex
steels is necessary in order to ensure that the phase balance and properties of the material are not affected during this process. Hybrid
arc-
laser welding is a perfect combination of the advantages of both processes, producing deeper weld beads with more balanced phases than the
pulsed laser process. Here, the objective was to improve the corrosion resistance of UNS S32750 weld beads by increasing the volumetric
austenite percentage in the fusion zone (FZ) with a hybrid process of GTAW (gas
tungsten arc welding) and
pulsed laser Nd-YAG (
neodymium-doped
yttrium aluminum garnet). Welds were performed in bead on plate conditions with fixed
laser parameters and a varying heat input introduced through the GTAW process. Additionally, welds within a
nitrogen atmosphere were performed. After base
metal characterization, an analysis of the FZ and heat affected zone were performed with optical microscopy, scanning electron microscopy and critical pitting tests (
CPT). The synergy between the thermal input provided by the hybrid process and
austenite-promoting characteristic of
nitrogen led to a balanced volumetric
austenite/
ferrite fraction. Consequently, the results obtained in
CPT tests were better than conventional welding processes, such as
laser or GTAW solely.