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Nickel Alloy Specs Guide: Composition, Properties & ASTM Standards

Complete technical reference for nickel alloy specifications: UNS numbers, chemical composition, mechanical properties, ASTM standards, and international equivalents.

📅 Updated: June 2026 ⏱️ 16 min read 👨‍🔧 Reference
AC

Aaron Cui

Nickel Alloy Expert · 30+ Years · Oil & Gas + Petrochemical

Nickel Alloy UNS Number Quick Reference

UNS NumberTrade NameFamilyKey Application
N04400Monel 400Ni-CuSeawater, HF acid
N06022Hastelloy C22Ni-Cr-MoMixed acid, FGD
N06022Hastelloy C276Ni-Cr-MoHCl, chlorides
N10675Hastelloy B3Ni-MoHCl, reducing acid
N06002Hastelloy XNi-Cr-Fe-MoHigh-temp oxidation
N06625Inconel 625Ni-Cr-Mo-NbHigh-temp + corrosion
N07718Inconel 718Ni-Cr-FeHigh-temp strength
N08020Alloy 20Ni-Fe-Cr-Mo-CuSulfuric acid
N08367254 SMO / AL-6XNSuper austeniticWarm seawater
N08904904LSuper austeniticWarm seawater
S31803Duplex 2205Duplex SSModerate seawater
S32750Super Duplex 2507Super duplexWarm seawater
S31254254 SMOSuper austeniticHigh chloride

Chemical Composition Comparison (wt%)

Hastelloy Family

GradeNiCrMoWFeCuOther
C27657161645
C2256221333
B3651.528.51.5
X4722918Co: 1.5

Inconel and Specialty Alloys

GradeNiCrMoNbFeCuOther
625582193.6Ti: 0.4
718531935.218Ti: 0.9, Al: 0.5
Monel 400671.531Mn: 2
Alloy 2036202.5383.5
254 SMO182060.7N: 0.2

Mechanical Properties

Room Temperature Minimum Properties (Annealed Plate)

GradeYield 0.2% (MPa)Tensile (MPa)Elongation (%)Hardness (HB)
C27631069040≤220
C2231069045≤220
B335076040≤235
X31072035≤220
Inconel 62541583030≤220
Inconel 7181030127512≤331
Monel 40024055035≤180
Alloy 2024055030≤160
254 SMO30065035≤230
Duplex 220545065525≤293
Super Duplex 250755080015≤310

Note: These are minimum values per ASTM specifications. Actual values from mill certificates may be higher. Inconel 718 properties shown are minimum (solution + age treated); solution annealed only: yield ~420 MPa.

ASTM Standards by Product Form

Plate, Sheet, Strip

B575 (Ni-Cr-Mo alloys)

B621 (Ni-Fe-Cr-Mo-Cu)

B424 (Ni-Fe-Cr-Al-Si)

Seamless Pipe & Tube

B622 (Ni-Cr-Mo-Nb alloys)

B677 (UNS N08366/N08904)

B165 (Monel 400)

Welded Pipe & Tube

B619 (welded Ni-Cr-Mo)

B626 (welded tube)

B673/674 (welded tube)

Bar, Rod, Wire

B574 (rod/bar Ni-Cr-Mo)

B164 (Monel rod)

B980 (Inconel rod)

Forgings

B564 (Ni alloy forgings)

B425 (Ni-Fe-Cr forgings)

B366 (fittings)

Castings

A494 (corrosion-resistant)

A743 (general steel castings)

A351 (austenitic)

International Equivalents

UNSEN / DIN / NWJIS / JapanGB / China
N044002.4360 / NiCu30FeNW 4400NS 312 (NCu30)
N060222.4602 / NiCr21Mo14WNS 3403
N06022 (C276)2.4819 / NiMo16Cr15WNW 0276NS 334
N066252.4856 / NiCr22Mo9NbNW 6625NS 336
N077182.4668 / NiCr19Nb5Mo3GH 4169
N083671.4529 / X1NiCrMoCuN25-20-7SUS 836L015Cr20Ni18Mo6CuN
N089041.4539 / X1NiCrMoCu25-20-500Cr20Ni25Mo4.5Cu
S318031.4462 / X2CrNiMoN22-5-3SUS 329J3L022Cr23Ni5Mo3N
S327501.4410 / X2CrNiMoN25-7-4SUS 327L022Cr25Ni7Mo4N

Nickel Alloy Mill Certificate: What to Check

EN 10204 3.1 Mill Certificate — Required Checks

Heat number matches stamped marking on product

Chemical composition within ASTM B575/B622 limits for each element

Mechanical properties: yield, tensile, elongation all ≥ ASTM minimums

Heat treatment condition: must be solution annealed for corrosion resistance grades

Intergranular corrosion test: required for some grades (verify if specified)

PMI verification: use XRF to independently verify composition — do not rely solely on mill cert

Specification Tips

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