Alloy31

Stainless Steel

Alloy31

Super-austenitic stainless steel. (UNS N08031; equiv Alloy 31 / UNS N08031). Nominal values—confirm mill certificate.

Chemical Composition (%)

C0.02
CR19
NI24
MO6
N0.15
CU0.5

Mechanical Properties

Tensile:≥650 MPa;Yield:≥300 MPa

Equivalent Grades

UNS N08031 Alloy31 / Alloy 31 / UNS N08031

Applications

超级奥氏体（同1.4529）。,"Plate

Available Forms

Tube"

Uses

Austenitic stainless steel with excellent corrosion resistance, formability and weldability; non-magnetic in annealed condition. High nickel (≈25%) stabilises the austenite and improves toughness and pitting resistance. Molybdenum (≈6.5%) enhances resistance to chloride pitting and crevice corrosion — suited to marine and chemical service. Used in food processing, chemical plant, architecture, heat exchangers, kitchenware and medical devices.

Heat Treatment

Solution anneal 1010–1150 °C followed by rapid water quench to retain austenite; not hardenable by heat treatment. Sensitization avoided by low carbon or stabilizers (Ti/Nb).

Precautions

Weld with low-carbon or stabilized filler (e.g., 316L, 347) to avoid sensitization; passivate after fabrication. Not hardenable, but work-hardens rapidly — use sharp tools and rigid setups. Avoid chloride contact for 304 in warm service; specify 316/317 for marine or aggressive media.

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