Duplex stainless steel ASTM A182 F51

ASTM A182 F51 is a duplex stainless steel with a 50:50 austenite, ferrite microstructure. The material combines good mechanical strength and ductility with moderate to good corrosion resistance in a variety of environments.

This material is generally supplied in the annealed condition giving yield strengths in excess of 65 KSI (450Mpa), this material cannot be hardened by heat treatment but stronger surface strengths can be achieved by cold working.

Typical applications include pumps,valves, pipework, flanges etc together with various applications in the oil and gas, brewing, power generation and chemical engineering industries. In fact this alloy can be used successfully as an alternative to 300 series austenitic stainless steels in almost all applications where higher mechanical strength/lower weight is required.

Typical Chemical composition
Carbon 0.03% Max
Silicon 1.00% Max
Manganese 2.00% Max
Phosphorous 0.035% Max
Sulphur 0.015% Max
Chromium 21.0 – 23.0%
Nickel 4.5 – 6.5%
Molybdenum 2.5 – 3.5%
Nitrogen 0.10 – 0.20%
PREn >34
Mechanical Property Requirements – Annealed condition
Yield Tensile Strength Elongation CharpyImpact @ Rt J Hardness
>450Mpa (65KSI) 650 – 800Mpa

(94 – 128KSI)

25% 100 270HB Max

Forging temperature for this material should be 1100-1250 ℃. Reheat as often as necessary and cool in still air.

Heat Treatment

Anneal – Heat to 1020 – 1120oC ensuring sufficient time is allowed for the centre to achieve furnace temperature and hold for a time commensurate with the ruling section, followed by water quenching.


Material in the annealed condition is readily machinable by all conventional methods.

F51 is readily weldable using many of the standard electric arc welding processes but oxyacetylene welding is not recommended because carbon pickup in the weld metal may occur.

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