Influence of the shielding gas composition on the passive film and erosion corrosion of tube-to-tube sheet welds of hyper duplex stainless steel

• Addition of nitrogen gas in shielding gas facilitated reformation of austenite phase.
• Addition of nitrogen gas improved the erosion corrosion resistance in the weld metal.
• Heat affected zones are susceptible to erosion corrosion damage.
• Increase of chemical species related to nitrogen improved stability of passive film.

Resistance to erosion corrosion was determined by degree of repair of passive film under flowing conditions combined corrosive solution. To examine effects of nitrogen addition to argon shielding gas on erosion corrosion of hyper duplex stainless steel welds, stability of oxide film passivity of hyper duplex stainless steel welds was measured through electrochemical tests and X-ray photoelectron spectroscopy analyses. The results indicated the resistance to erosion corrosion was improved due to the increase of austenite phase and the stability of the passive film resulting in change of chemical species as supplemented with the nitrogen gas in the argon shielding gas.