Effect of nitrogen-containing shielding and backing gas on the pitting corrosion resistance of welded lean duplex stainless steel LDX 2101® (EN 1.4162, UNS S32101)

Westin, Elin M.; Johansson, Mikael; Pettersson, Rachel

doi:10.1007/s40194-013-0046-2

Cited by 45 publications

(20 citation statements)

References 19 publications

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“…By adding nitrogen to the backing gas, localized corrosion was avoided. This is consistent with previous research [8,12] concluding that the presence of nitrogen prevents nitrogen loss and forms a protective thin layer of austenite at the weld root surface, which assists to prevent pitting corrosion. With Ar + 2% N 2 there was still a small weight loss of 1.7 g/m 2 exceeding what is allowed in ASTM A923 (1 g/m 2 ).…”

Section: Discussionsupporting

confidence: 93%

“…100% Ar as backing gas showed localized corrosion attack in the weld metal and corresponding high weight loss. This is correlated to nitrogen loss at the very surface resulting in higher weld metal ferrite content and exposing chromium nitrides to the corrosive medium [8,12]. Pitting takes preference to the ferrite phase.…”

Section: Discussionmentioning

confidence: 99%

“…Nitrogen can be added to the shielding and backing gases to avoid this occurring. The effects of using nitrogen in the shielding and/or backing gas has been investigated by various authors who have reported an increased resistance to pitting corrosion by increased austenite formation and lower levels of chromium nitrides in the weld metal microstructure [3,[6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Effect of nitrogen in backing gas on duplex root weld properties of heavy-walled pipe

Sales¹,

Westin

Colegrove

2016

Weld World

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Duplex stainless steels are increasingly used for offshore subsea components as the technology allows for deeper recovery of oil & gas reserves. Alloy UNS S31803 (EN 1.4462 / UNS S32205) combines high strength with good resistance to pitting and crevice corrosion. This grade is alloyed with nitrogen and has good weldability. For heavy-walled process piping intended for subsea sour service, the properties of the root pass are of high importance. For this reason, the effect of using nitrogen in the backing gas was investigated. Test pieces were manually welded with the gas tungsten arc welding (GTAW) process using ER2209 filler wire. Tensile, bending and hardness testing was carried out and showed acceptable results across all specimens. Higher contents of nitrogen in the backing gas showed more austenite formation and a significant increase in pitting corrosion resistance when compared with pure argon. With Ar + 2% N 2 , there was no pitting, but a small weight loss of 1.7 g/m 2 was measured. 10% N 2 was required to pass both the corrosion tests ASTM G48 Method A (4 g/m 2 ) and ASTM A923 (1 g/m 2 ). The highest average impact toughness was achieved with pure nitrogen as the backing gas.Heavy-walled pipe used for the collection of hydrocarbons subsea are increasingly exposed to harsh conditions and the internal root welds are exposed to high levels of H 2 , H 2 S, and CO 2. The expectation for a lengthy service

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of nitrogen in backing gas on duplex root weld properties of heavy-walled pipe

Sales¹,

Westin

Colegrove

2016

Weld World

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“…This finding can be important when using nitrogen or nitrogen-containing mixtures as backing gas (Refs. 13,32,33) and requires more attention in the case of multipass welding, where the root pass is continuously reheated.…”

Section: Pseudo-nitriding Simulations In a Gleeble ® Physical Simulatmentioning

confidence: 99%

Weldability of Duplex Stainless Steels - Thermal Cycle and Nitrogen Effects

2019

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“…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%

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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Effect of nitrogen-containing shielding and backing gas on the pitting corrosion resistance of welded lean duplex stainless steel LDX 2101® (EN 1.4162, UNS S32101)

Cited by 45 publications

References 19 publications

Effect of nitrogen in backing gas on duplex root weld properties of heavy-walled pipe

Effect of nitrogen in backing gas on duplex root weld properties of heavy-walled pipe

Weldability of Duplex Stainless Steels - Thermal Cycle and Nitrogen Effects

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

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