Effect of nitrogen in shielding gas of keyhole GTAW on properties of duplex and superduplex welds

Sales, Andrew; Westin, Elin M.; Jarvis, B.L.

doi:10.1007/s40194-017-0486-1

Cited by 21 publications

(10 citation statements)

References 17 publications

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“…This observation has practical importance, because this is the N2 content range, where shielding gases are used for DSS TIG welding. Moreover, many researchers [23,24,54] observed sometimes contradictory results of γ content in the WM, using this shielding gas range for TIG welding, which could originate from this effect of the arc voltage changes. Table 3.…”

Section: Effects Of Shielding Gas Nitrogen Content On the Arc Voltagementioning

confidence: 99%

“…During arc welding of DSSs, the nitrogen loss from the weld metal (WM) leads toward more ferritic microstructures and to the loss of the abovementioned properties [21,22]. In order to balance this nitrogen loss, nitrogen (N 2 )-argon (Ar) (or helium) mixed shielding gases are used in industrial applications for DSS tungsten inert gas (TIG) welding [23][24][25]. The N 2 dissociates at the arc plasma temperature and the atomic nitrogen can dissolve in the molten pool [26].…”

Section: Introductionmentioning

confidence: 99%

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Physical and Theoretical Modeling of the Nitrogen Content of Duplex Stainless Steel Weld Metal: Shielding Gas Composition and Heat Input Effects

Varbai

Májlinger

2019

Metals

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Duplex stainless steels (DSSs) are gaining more and more attention in corrosion-resistant applications and also in the transport and automotive industry. The outstanding mechanical and corrosion properties of DSSs highly depends on the austenite-to-ferrite phase balance (A/F). This phase ratio can shift in a large scale during welding. Thus, the heat input and the shielding gas composition should be optimized. Nitrogen addition to argon shielding is frequently used in DSS welding, because it is a potent austenite former. The dissolved nitrogen content in the heat-affected zone and the weld metal (WM) predetermines the A/F. To determine the effect of heat input and nitrogen content in shielding gas, two different heat inputs and six different gas compositions were used in autogenous tungsten inert gas welding. An improved theoretical model was established in order to simulate the WM dissolved nitrogen content, which calculates it with less error than the initial models. The correlation between nitrogen content and arc voltage was also determined. This improved model delivers the basics for shielding gas selection and the subsequent weld design for optimal A/F for industrial applications.

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Section: Effects Of Shielding Gas Nitrogen Content On the Arc Voltagementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Physical and Theoretical Modeling of the Nitrogen Content of Duplex Stainless Steel Weld Metal: Shielding Gas Composition and Heat Input Effects

Varbai

Májlinger

2019

Metals

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“…Several authors have been mentioning the important role of N 2 in the microstructure evolution by being the strongest austenite forming alloying element 6,9,10,[13][14][15][16][17] . Moreover, N 2 is an economical and efficient substitute for nickel 10,17 .…”

Section: Introductionmentioning

confidence: 99%

“…Nitrogen is added to argon shielding gas in duplex stainless-steel welds to preserve weld metal nitrogen levels 15,16 . According to Zhang et al 15 , there are two ways to compensate for the nitrogen loss during welding: one is directly adding the nitrogen to the BM and filler wires in the originally producing supplies 13,17,23 or a proper proportion of nitrogen gas is added into shielding gas and backing gas during welding 11,14,16,[24][25][26][27][28] .…”

Section: Introductionmentioning

confidence: 99%

Effect of Nitrogen Addition to Shielding Gas on Cooling Rates and in the Microstructure of Thin Sheets of Duplex Stainless Steel Welded by Pulsed Gas Tungsten Arc Welding Process

et al. 2019

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The effect of the nitrogen content in the shielding gas and its effect on temperature distributions at the welded zone of thin sheets of duplex stainless steel have been evaluated. The duplex stainless steels have many features due to unique microstructural combination of austenite and ferrite grains. The phase balance can be easily shifted depending on the welding parameters. Two sheets were welded using pure argon and pure argon plus 2% of nitrogen as shielding gas. The thermal profile had shown that N 2-supplemented shielding gas lead to higher peaks of temperature using similar welding parameters. Microstructural examination showed that the austenite phase in the weld increased with the presence of nitrogen in the shielding gas. The added nitrogen promoted primary austenite formation and slightly increases the microhardness at the solidified zone. Microhardness mapping and metallographic imaging presented information about microstructures, confirming the formation of secondary phases during thermal cycle in the temperature range 850 °C and 950 °C. Control of ferrite amounts in the welds is essential mainly to improve mechanical properties and corrosion resistance of welding zones.

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“…Pure Ar is the most commonly used purging gas in GTA welding of several grades of steels [4]. In addition, at least 2% nitrogen would be recommended in pure argon mixture for shielding gas for optimizing the phase balance and impact toughness do DSS [5]. Taking all aspects into account, Ar + 2%N2 is the preferred shielding gas for welding duplex and super duplex with the GTAW process [5,6].…”

Section: Introductionmentioning

confidence: 99%

Effect of the cooling rates on heat-affected zone of UNS S32304 duplex stainless steel welded by pulsed GTAW process

Betini¹,

Gomes²,

Reis³

et al. 2017

Blucher Physics Proceedings

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Two thin plates of UNS 32304 of duplex stainless steel were joined by pulsed gas tungsten arc welding (GTAW) using a mixture 98% of argon plus 2% of nitrogen as shielding gas or pure argon as purging gas at the bottom of the plate without filler metal. The temperature profile close and away from the weld pool was measured using K type (Ni-Cr) thermocouples, connected to a digital data acquisition system. The thermal cycles was recorded in the heat-affected zone (HAZ) at a distance in between 1 and 3 mm from the joint line. The cooling rate and holding time were studied with respect to the used purging gas. Experimental thermal profiles are in good agreement with literature values. The joints welded without any purging gas revealed high peak temperature and cooling rates. The present investigation showed that temperature peaks are comprised in the phase transformation temperature ranges for the welded duplex stainless steel.

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Effect of nitrogen in shielding gas of keyhole GTAW on properties of duplex and superduplex welds

Cited by 21 publications

References 17 publications

Physical and Theoretical Modeling of the Nitrogen Content of Duplex Stainless Steel Weld Metal: Shielding Gas Composition and Heat Input Effects

Physical and Theoretical Modeling of the Nitrogen Content of Duplex Stainless Steel Weld Metal: Shielding Gas Composition and Heat Input Effects

Effect of Nitrogen Addition to Shielding Gas on Cooling Rates and in the Microstructure of Thin Sheets of Duplex Stainless Steel Welded by Pulsed Gas Tungsten Arc Welding Process

Effect of the cooling rates on heat-affected zone of UNS S32304 duplex stainless steel welded by pulsed GTAW process

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