Nickel alloy castings: ASTM A494, A297 and A560 grades

A nickel-base alloy casting is one in which nickel, not iron, is the main element. Two standards families cover most of them. ASTM A494 covers nickel and nickel alloy castings for corrosion-resistant service: cast nickel (CZ-100), nickel-copper (M35-1, the cast Monel 400 type), nickel-chromium (CY-40, cast Alloy 600) and nickel-chromium-molybdenum (CW-6MC, cast Alloy 625). For heat-resistant service, ASTM A297 grades HW and HX and ASTM A560 50Cr-50Ni-Nb are the nickel-base members.

Published 15 Nov 2026 · Updated 15 Nov 2026 · Ni-Chrome Alloy Castings

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Why use a nickel-base casting instead of stainless?

Stainless castings such as CF8M run out in a few well-defined places, and nickel alloys take over there:

Chloride stress-corrosion cracking. High-nickel alloys resist it where 300-series stainless cracks.
Hot caustic. Nickel and nickel-chromium grades are the standard materials for concentrated sodium hydroxide.
Seawater, brine and hydrofluoric acid. Nickel-copper grades are used for pumps and valves in these.
Pitting, crevice corrosion and sour service. Nickel-chromium-molybdenum grades such as CW-6MC handle the most aggressive chloride and sour streams.
Heat with carburisation or thermal cycling. High-nickel heat-resistant grades (HW, HX) hold up in carburising and cyclic furnace duty where lower-nickel H-grades crack or grow.

The price is nickel content. Choose a nickel alloy where it is the cheapest material that survives, not by default.

What is the composition of the ASTM A494 nickel alloy grades?

ASTM A494 covers "nickel, nickel-copper, nickel-copper-silicon, nickel-molybdenum, nickel-chromium, and nickel-molybdenum-chromium alloy castings for corrosion-resistant service." The four most commonly specified grades are below, in weight percent.

Element	CZ-100	M35-1	CY-40	CW-6MC
Nickel	95.0 min	Balance	Balance	Balance
Chromium	-	-	14.0 to 17.0	20.0 to 23.0
Molybdenum	-	-	-	8.0 to 10.0
Niobium	-	see note	-	3.15 to 4.50
Copper	1.25 max	26.0 to 33.0	-	-
Iron	3.0 max	3.5 max	11.0 max	5.0 max
Carbon	1.00 max	0.35 max	0.40 max	0.06 max
Silicon	2.00 max	1.25 to 2.00 max	3.00 max	1.00 max
Manganese	1.50 max	1.50 max	1.50 max	1.00 max
Wrought counterpart	Nickel 200 type	Monel 400 type	Alloy 600 type	Alloy 625 type

Source: ASTM A494/A494M Table 1 as compiled by MakeItFrom for each grade. Phosphorus and sulphur limits are omitted here. For M35-1, sources differ on silicon (1.25 max in the standard text we compiled, 2.00 in one foundry listing) and on whether a niobium limit applies (0.5 max in the standard text, not shown in foundry listings), so confirm both against the edition on your order. A494 also lists further grades (M35-2, M30C, M25S, N-12MV, N-7M, CW-12MW, CW-6M, CW-2M, CX2MW, CU5MCuC and others). The edition named on your purchase order governs.

Carbon is the clearest difference from the wrought alloys. CZ-100 allows up to 1.00% carbon and CY-40 up to 0.40%, far above the wrought equivalents, because carbon and silicon help the metal flow and feed in the mould. CW-6MC keeps carbon at 0.06% maximum to protect corrosion resistance, which makes it the hardest of the four to cast sound.

What are the heat-resistant nickel-base grades?

Three heat-resistant grades have nickel as the largest element. They are bought for furnace duty, not wet corrosion.

Grade	Standard	UNS	Chromium, wt %	Nickel, wt %	Carbon, wt %
HW (12Cr-60Ni)	ASTM A297	N08001	10.0 to 14.0	58.0 to 62.0	0.35 to 0.75
HX (17Cr-66Ni)	ASTM A297	N06006	15.0 to 19.0	64.0 to 68.0	0.35 to 0.75
50Cr-50Ni-Nb	ASTM A560	R20501	47 to 52	Balance	0.10 max

Sources: ASTM A297/A297M-21a Table 1 (HW, HX; Mn 2.00 max, Si 2.50 max, Mo 0.50 max); ASTM A560 grade 50Cr-50Ni-Cb, also with niobium 1.4 to 1.7. See the 50Cr-50Ni-Nb grade page.

HW and HX are used for heat-treatment fixtures, retorts, muffles and parts in carburising and cyanide-hardening service, where their high nickel resists carbon pick-up and the cracking that comes with repeated heating and quenching. 50Cr-50Ni-Nb is the fuel-ash grade for fired heater tube supports.

What properties do nickel alloy castings have?

Typical room-temperature values published for the A494 grades are below. They are typical figures, not specification minimums, and they depend on heat treatment and section size.

Grade	Tensile strength, MPa	Yield strength, MPa	Elongation, %	Condition
CZ-100	390	140	11	As cast
M35-1	500	190	28	As cast
CY-40	540	220	34	As cast
CW-6MC	540	310	28	Heat treated

Source: MakeItFrom typical values for each A494 grade. Specified minimums are lower: for CZ-100, for example, 345 MPa tensile, 125 MPa yield and 10% elongation, and for M35-1 450 MPa tensile and 25% elongation (Total Materia). Order to the minimums in the edition of A494 on your purchase order.

A494 requires the castings to be heat treated, with grade-specific rules. CY-40, for example, is supplied as cast when Class 1 is ordered and solution treated when Class 2 is ordered, so the class must be on the order.

Where are nickel alloy castings used?

CZ-100: pumps, valves and fittings in hot concentrated caustic soda and other alkali service, and in food and chemical processing where iron contamination must be avoided.
M35-1: seawater and brine pump casings, impellers and valve bodies, and hydrofluoric acid service.
CY-40: caustic and high-purity-water service, and parts that need resistance to chloride stress-corrosion cracking.
CW-6MC: severe chloride, seawater, acid and sour service, and parts that combine corrosion with elevated temperature.
HW and HX: heat-treatment furnace fixtures, trays, retorts and muffles, carburising and cyanide-hardening equipment.
50Cr-50Ni-Nb: fired heater tube supports, hangers and tube sheets exposed to fuel-oil ash.

What are the castability limits of nickel alloys?

Gas and contamination. Molten nickel alloys pick up gas and are sensitive to tramp elements such as sulphur and lead, which cause porosity and hot cracking. Clean charge materials and controlled melting matter more than for steel.
Shrinkage and feeding. Low-carbon grades such as CW-6MC are less fluid and need careful risering to avoid shrinkage in heavy sections.
Heat treatment. Several A494 grades must be solution treated after casting to reach their corrosion resistance and ductility.
Weld repair. Repairs need procedures qualified for the grade, with matching nickel-alloy filler.
Air melting versus vacuum. The grades on this page are air-melted and cast in sand moulds. Precipitation-hardened gas-turbine superalloys (IN-713, IN-738, Mar-M and similar) are a different family, vacuum-melted and investment cast.

Is MP35N available as a casting?

MP35N is a wrought cobalt-nickel-chromium-molybdenum alloy (UNS R30035), nominally 35% cobalt, 35% nickel, 20% chromium and 10% molybdenum. Producers make it by vacuum induction melting followed by vacuum arc remelting, and supply it as bar, wire and strip that is cold worked and aged for strength. It is not a sand-casting alloy. Where a cast cobalt-chromium-molybdenum part is needed, see the cobalt alloy castings page.

Which casting route suits nickel alloys?

Valve bodies, pump casings, impellers, fixtures and supports are cast statically in sand moulds. Round parts such as sleeves, rings and bushes can be cast centrifugally.

We cast the A494 grades CY-40, CW-6MC and M35-1, the A297 high-nickel grades HW and HX, and A560 50Cr-50Ni-Nb, in sand moulds and centrifugally.

What should an RFQ for nickel alloy castings include?

The standard and grade, for example ASTM A494 CW-6MC, and the class or heat-treatment condition where the standard offers a choice.
If the drawing names a wrought alloy or trade name, the cast grade you accept as its equivalent, or the full chemistry you require.
The drawing with tolerances, machining and finished weight if known.
Service: the fluid, its concentration, temperature and chlorides for corrosion duty, or temperature and atmosphere for heat duty.
Testing: chemistry and tensile certificates, radiography or penetrant extent and acceptance level, PMI, any corrosion test, and third-party inspection.
Quantity, delivery needs and any end-user or EPC contractor approval required.

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Nickel alloy questions

Is CW-6MC the same as Inconel 625?

CW-6MC is the cast grade in ASTM A494 with nominal Alloy 625 chemistry. Inconel is a trade name of its owner. Wrought 625 and cast CW-6MC are bought to different standards and differ in properties, so order the cast grade by its A494 name.

Is CY-40 the same as Alloy 600?

CY-40 is the cast counterpart of Alloy 600, with more carbon and silicon allowed so it casts well. It is ordered to ASTM A494, and Class 1 (as cast) or Class 2 (solution treated) has to be stated.

What is M35-1?

The ASTM A494 nickel-copper grade with 26 to 33% copper, the cast form of Monel 400 type alloy, used for seawater and hydrofluoric acid service.

Are HW and HX nickel-base alloys?

Yes. Both carry about 60 to 68% nickel. They sit in ASTM A297 with the iron-base H-grades because they were developed as heat-resistant castings.

Can nickel superalloys for gas turbines be sand cast?

Generally not. Turbine-blade alloys contain aluminium and titanium that oxidise in air, so they are vacuum-melted and investment cast. The air-melted nickel grades on this page cover corrosion and furnace duty.