Duplex Stainless Steel
A stainless steel with a roughly 50/50 ferrite-austenite microstructure, giving about twice the yield strength of austenitic grades together with strong chloride stress corrosion resistance.
Why fabricators like it
At 450 MPa minimum yield, duplex 2205 lets a designer take thickness out of a vessel that would otherwise be built in 316L at 200 MPa. The saving is in plate weight, weld volume and handling.
What it demands in return
Heat input has to be controlled between about 0.5 and 2.5 kJ/mm, interpass temperature kept below 150 °C, and the ferrite/austenite balance checked — because sigma phase forming between 600 and 1000 °C will wreck both toughness and corrosion resistance. Form it warm, and solution anneal plus water quench after hot forming.
Related terms
Where this applies
Duplex & Super Duplex Plate
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