| 1. |
- Svensson, Lars-Erik, 1951-, et al.
(författare)
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Strength and Impact Toughness of High Strength Steel Weld Metals : Influence of Welding Method, Dilution and Cooling Rate
- 2015
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Ingår i: Proceedings of IIW International Conference, High-Strength Materials. - Helsingfors. ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- Producing welds with properties matching those of the steel is a challenge at high strength levels. The present study has investigated how the choice of welding method affects weld metal mechanical properties through effects on dilution and cooling rate. Butt welds were produced in 12 mm plates in 777 MPa and 1193 MPa yield strength steels. Conventional arc welding methods including manual metal arc, gas metal arc welding, rapid arc welding and submerged arc welding were used as well as laser-gas metal arc hybrid welding. Filler materials with nominal yield strengths between 810 and 1000 MPa were used. Cooling times between 800 C and 500 C were varied between 5s and 15s and measured by insertion of thermocouples into the weld pool.High quality welds were produced efficiently with all welding methods even though dilution varied between 3%, for manual metal arc welding, to 73% for laser-hybrid welding. Low dilution, rapid cooling and single pass welding contributed to higher strength. Overmatching weld metal strength was achieved for the less strong steel and weld yield strengths of >1000 MPa were recorded for the stronger steel. Fracture in transverse tensile testing was always located in base material or HAZ. Impact toughness was higher for lower strength and low dilution. Results are discussed relating choice of welding method and cooling rate to weld metal properties for different steel strength levels.
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| 2. |
- Valiente Bermejo, María Asunción, 1972-, et al.
(författare)
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Effect of shielding gas on welding performance and properties of duplex and superduplex stainless steel welds
- 2015
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Ingår i: Welding in the World. - : Springer Science and Business Media LLC. - 0043-2288 .- 1878-6669. ; 59:2, s. 239-249
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Tidskriftsartikel (refereegranskat)abstract
- The influence of shielding gases on welding performanceand on properties of duplex and superduplex stainlesssteel welds was studied. Using argon as the reference gas,helium, nitrogen and carbon dioxide were added and fivemixtures evaluated. Bead-on-plate welds and circumferentialpipe welds were produced using mechanisedGMAwelding inthe downhand position. Welding performance, corrosion resistance,mechanical properties, microstructural features andweld imperfections were assessed and related to the shieldinggas. Shielding gases containing 30 % helium showed excellentresults; whilst pure argon showed unstable arc and poorweld pool fluidity and Ar+2 %CO2 resulted in underfill andporosity. Mixtures containing helium resulted in higher ductilitywelds and higher impact toughness values than weldsproduced with Ar+2 %CO2. Sound and balanced duplexmicrostructures free from intermetallics were found with suitableferrite contents for all the shielding gases studied. All theduplex pipe welds passed the corrosion test regardless of theshielding gas used, and the best results in the corrosion test forsuperduplex pipe welds were found when using Ar+30 %He+0.5 %CO2+1.8 %N2 as shielding gas.
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| 3. |
- Valiente Bermejo, María Asunción, 1972-, et al.
(författare)
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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
- 2016
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Ingår i: Rivista Italiana della Saldatura. - : Istituto Italiano della Saldatura. - 0035-6794. ; 68:5, s. 635-650
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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