Duplex stainless combines higher strength with better stress corrosion resistance. Learn which applications justify its cost and what to watch for in fabrication.
Duplex is an alloy with two metallic phases in similar amounts: austenite and ferrite. This structure gives it roughly twice the yield strength of austenitic grades like 304 and 316, with high resistance to chloride stress corrosion cracking.
The most common grade is 2205, with higher grades (super duplex) for the harshest conditions.
Duplex costs more per tonne, but its higher strength often allows thinner walls, which lowers total weight and the real material cost. Once service life, downtime and replacement costs are counted, duplex is in many cases the more economical choice in the long run.
Welding duplex requires qualified welding procedures, careful control of heat input and interpass temperature, and the right filler metals to keep the two phases balanced. Fabrication should therefore be done by a shop with proven experience and documented tests on this alloy.
Material Selection
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Stainless Steel
A simple comparison of the two most common stainless grades by composition, chloride resistance and cost, and when upgrading to 316 is necessary.
Fabrication
A metal part's journey through the shop step by step: from drawing review and material preparation, through cutting, forming and welding, to inspection and delivery.
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Stainless Steel
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