Welding duplex stainless steel: heat input, interpass temperature and ferrite balance

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duplex · welding · heat input · ferrite

Duplex welding is mainly about heat input and cooling rate to keep the ferrite/austenite balance. Too much or too little heat input both raise corrosion and toughness risks.

Welding duplex stainless steel is more sensitive than austenitic grades. The core objective is to control the ferrite/austenite balance in the weld and HAZ (typically 35%–65% ferrite).

Key controls:

1) Heat input: typically 0.5–2.5 kJ/mm depending on thickness and procedure qualification. Too high causes coarse grains and nitride precipitation; too low leaves insufficient austenite and lower corrosion resistance.
2) Interpass temperature: usually below 150°C to avoid overheating.
3) Shielding gas: Ar + N₂ mixtures or nitrogen backing gas help austenite formation.
4) Filler metal: use matching duplex consumables (e.g. ER2209), not 316L.
5) Post-weld: solution annealing is usually not required, but pickle and passivate to restore surface corrosion resistance.
6) Inspection: ferrite content measurement (magnetic/metallographic), pitting and bend tests per code.

Purchasing and construction advice: require WPS/PQR and ferrite test reports; control heat input and interpass temperature on site instead of rushing continuous welding.

本文由 SteelWe 编辑与行业专家整理，内容仅供行业交流参考，不构成交易或投资建议。引用请注明来源。

Welding duplex stainless steel: heat input, interpass temperature and ferrite balance

Duplex welding is mainly about heat input and cooling rate to keep the ferrite/austenite balance. Too much or too little heat input both raise corrosion and toughness risks.

Welding duplex stainless steel is more sensitive than austenitic grades. The core objective is to control the ferrite/austenite balance in the weld and HAZ (typically 35%–65% ferrite).

Key controls:

1) Heat input: typically 0.5–2.5 kJ/mm depending on thickness and procedure qualification. Too high causes coarse grains and nitride precipitation; too low leaves insufficient austenite and lower corrosion resistance.
2) Interpass temperature: usually below 150°C to avoid overheating.
3) Shielding gas: Ar + N₂ mixtures or nitrogen backing gas help austenite formation.
4) Filler metal: use matching duplex consumables (e.g. ER2209), not 316L.
5) Post-weld: solution annealing is usually not required, but pickle and passivate to restore surface corrosion resistance.
6) Inspection: ferrite content measurement (magnetic/metallographic), pitting and bend tests per code.

Purchasing and construction advice: require WPS/PQR and ferrite test reports; control heat input and interpass temperature on site instead of rushing continuous welding.

本文由 SteelWe 编辑与行业专家整理，内容仅供行业交流参考，不构成交易或投资建议。引用请注明来源。