Duplex Stainless Steel Weld Integrity and Corrosion Resistance

Duplex stainless steels combine roughly equal proportions of ferrite and austenite to deliver high strength, toughness and excellent resistance to general and localised corrosion. Welding these alloys demands precise control of heat input and cooling rates to preserve the duplex balance and to avoid deleterious intermetallic phases such as sigma and chi, which can embrittle the material and undermine its resistance to pitting and stress corrosion cracking. The heat-affected zone (HAZ) is especially vulnerable, as thermal cycles can provoke chromium depletion in ferrite, promote secondary phase precipitation and induce localised acidification in aggressive environments. Optimising welding parameters, filler compositions and post-weld heat treatments is therefore critical to maintain weld integrity for applications ranging from subsea pipelines and chemical process vessels to heat exchangers in power generation plants. Global demand for reliable corrosion-resistant welds continues to drive innovations in thermomechanical processing, non-destructive assessment and alloy design to ensure long service life under harsh operating conditions.

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Duplex Stainless Steel Weld Integrity and Corrosion Resistance publication trend

The graph below shows the total number of articles in duplex stainless steel weld integrity and corrosion resistance across all publications each year (not limited to Nature Index journals).

Technical terms

Duplex microstructure: A two-phase mixture of austenite and ferrite engineered to combine high strength with superior corrosion resistance.

Heat-affected zone (HAZ): The region adjacent to a weld where thermal cycles alter phase balance, grain structure and local chemistry.

Sigma phase: A brittle intermetallic compound rich in chromium and molybdenum that precipitates in duplex steels at 600–900 °C, reducing toughness and corrosion resistance.

Pitting corrosion: Localised attack leading to cavity formation, typically initiated at inclusions, second-phase precipitates or chromium-depleted sites.

Sensitisation: Chromium depletion around grain boundaries or precipitates, which impairs the formation of a protective oxide film and increases intergranular corrosion risk.

References

1. Microstructure and corrosion behavior of welded joint between 2507 super duplex stainless steel and E690 low alloy steel. Corrosion Communications (2023).
2. Micro-electrochemical insights into pit initiation site on aged UNS S32750 super duplex stainless steel. npj Materials Degradation (2023).
3. Time-temperature-precipitation and property diagrams for super duplex stainless steel weld metals. Welding in the World (2018).
4. Effects of Heat Input on Microstructure, Corrosion and Mechanical Characteristics of Welded Austenitic and Duplex Stainless Steels: A Review. Metals (2017).