Influenza del gas di protezione sul comportamento e le proprietà  di giunti sa dati di acciai duplex e superduplex : Effect of shielding gas on welding performance and properties of duplex and superduplex stainless steel welds

• The influence of shielding gases on welding performance and on properties of duplex and superduplex stainless steel welds was studied. Using argon as the reference gas, helium, nitrogen and carbon dioxide were added and five mixtures evaluated. Bead-on-plate welds and circumferential pipe welds were produced using mechanised GMA welding in the downhand position. Welding performance, corrosion resistance, mechanical properties, microstructural features and weld imperfections were assessed and related to the shielding gas. Shielding gases containing 30% helium showed excellent results; whilst pure argon showed unstable arc and poor weld pool fluidity and Ar + 2% CO2resulted in underfill and porosity. Mixtures containing helium resulted in higher ductility welds and higher impact toughness values than welds produced with Ar + 2% CO2. Sound and balanced duplex microstructures free from intermetallics were found with suitable ferrite contents for all the shielding gases studied. All the duplex pipe welds passed the corrosion test regardless of the shielding gas used, and the best results in the corrosion test for superduplex pipe welds were found when using Ar + 30%He + 0.5% CO2+ 1.8% N2as shielding gas.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Bearbetnings-, yt- och fogningsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Manufacturing, Surface and Joining Technology (hsv//eng)

Nyckelord

Argon; Atmospheric corrosion; Carbon; Carbon dioxide; Corrosion; Corrosion resistance; Electric arc welding; Gas metal arc welding; Gases; Helium; Intermetallics; Laser beam welding; Mechanical properties; Microstructural evolution; Mixtures; Nitrogen; Shielding; Welding; Welds

Corrosion tests; Duplex microstructures; Duplex stainless steel; Ferrite content; GMA welding; Microstructural features; Shielding gas; Superduplex stainless steels

Stainless steel

Production Technology

Produktionsteknik

Manufacturing and materials engineering

Produktions- och materialteknik

Publikations- och innehållstyp

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