Hastelloy Alloys
Hastelloy is the nickel-molybdenum family for wet corrosion: 13–30 % molybdenum, 0–23 % chromium and a few percent tungsten in a nickel base, with carbon and silicon held so low that the alloys stay corrosion-resistant as welded. The C grades (Hastelloy C276, Hastelloy C-22, Hastelloy C-2000) handle oxidizing and reducing media alike — wet chlorine, hypochlorite, hot contaminated sulfuric and hydrochloric acid, ferric and cupric chlorides; the B grades (Hastelloy B-3) take pure hydrochloric and sulfuric acid to boiling; Hastelloy X is the high-temperature sheet alloy for combustors to 1,200 °C. Yield strength runs 300–400 MPa annealed with 40–60 % elongation.
Popular Hastelloy grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| Hastelloy C276 | 360 | 790 | 8.89 | Poor | Excellent | The default for mixed and unknown wet chemistry |
| Hastelloy C-22 | 395 | 800 | 8.69 | Poor | Excellent | Oxidizing media and wet chlorine; universal filler base |
| Hastelloy C-2000 | 355 | 760 | 8.5 | Poor | Excellent | Most versatile C grade; also reducing sulfuric acid |
| Hastelloy B-3 | 385 | 830 | 9.24 | Poor | Very good | Hydrochloric and sulfuric acid to boiling, no oxidizers |
| Hastelloy X | 360 | 755 | 8.22 | Poor | Excellent | Combustor cans and ducting to 1,200 °C |
| Hastelloy G-3 | 310 | 690 | 8.31 | Poor | Excellent | Sour gas, phosphoric acid and mixed acids with halides |
| Alloy 59 | 360 | 740 | 8.6 | Poor | Excellent | Copper-free C-2000 equivalent; FGD and pharma plant |
All 49 Hastelloy grades
- Alloy 22
- Alloy 30
- Alloy 31
- Alloy 59
- CU5MCuC
- CW-6MC
- CW-12MW
- CW2M
- CW6M
- CX2M
- CX2MW
- ENiCrMo-1
- ENiCrMo-3
- ENiCrMo-4
- ENiCrMo-7
- ENiCrMo-10
- ENiCrMo-13
- ENiCrMo-14
- ENiMo-7
- ERNiCrMo-1
- ERNiCrMo-2
- ERNiCrMo-3
- ERNiCrMo-4
- ERNiCrMo-7
- ERNiCrMo-10
- ERNiCrMo-13
- ERNiCrMo-14
- ERNiMo-3
- ERNiMo-7
- Hastelloy B
- Hastelloy B-2
- Hastelloy B-3
- Hastelloy B-4
- Hastelloy C-4
- Hastelloy C-22
- Hastelloy C-2000
- Hastelloy C276
- Hastelloy G
- Hastelloy G-2
- Hastelloy G-3
- Hastelloy N
- Hastelloy S
- Hastelloy W
- Hastelloy X
- N-12M-1
- N7M
- N12MV
- N06035
- N10624
Choose Hastelloy for
Chemical reactors, columns and heat exchangers in mixed or contaminated acids; flue-gas desulfurization absorbers and stacks; pulp-bleach and wet-chlorine equipment; pickling tanks and pharmaceutical reactors; sour-gas tubing and valves; and — Hastelloy X only — gas-turbine combustor liners, transition pieces and furnace muffles to 1,200 °C.
Look elsewhere when
A super-austenitic (254 SMO, AL-6XN) or super-duplex (2507) survives the chloride duty at a fraction of the cost; the job is heat with mechanical load (Inconel 718 to 650 °C, Waspaloy above); the acid is hydrofluoric (Monel 400); the medium is hot caustic (Nickel 200 or Inconel 600); or the acid is pure and reducing, where Hastelloy B-3 is the right member and the C grades are more alloy than the job needs. Hastelloy is never chosen for strength.
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Hastelloy by application
- Mixed and contaminated acids
- Hastelloy C276 for reactors, agitators, valves and pumps where sulfuric, hydrochloric, chlorides and oxidizers meet; Hastelloy C-2000 or Hastelloy C-22 where nitric acid or ferric chloride tips the balance toward oxidizing.
- Scrubbers and wet chlorine
- Hastelloy C-22 and Hastelloy C276 sheet and clad plate for FGD absorber outlet ducts, stack liners, wet-chlorine headers and hypochlorite service; Alloy 59 for the same duty on European drawings.
- Pure hydrochloric and sulfuric acid
- Hastelloy B-3 for HCl at every concentration to the boiling point and for hot reducing sulfuric, acetic and phosphoric acid — only when the acid is free of air, ferric and cupric ions.
- Combustors and hot ducting
- Hastelloy X for combustor cans, transition ducts, afterburner parts, furnace muffles and flame holders to 1,200 °C; it forms and welds like a heavy stainless and is not a wet-corrosion alloy.
Working with Hastelloy
- Machining
- As slow as Inconel 718: 20–30 m/min with coated carbide, instant work hardening, heat into the tool and abrasive chips. Rigid setups, sharp positive inserts, heavy constant feed and flood coolant; never dwell. All grades are machined solution-annealed — there is no hardened state to work around.
- Welding
- Matching filler — ERNiCrMo-4 for Hastelloy C276, ERNiCrMo-10 for Hastelloy C-22 (and as the universal filler for the C family), ERNiMo-7 for Hastelloy B-3, ERNiCrMo-2 for Hastelloy X — by TIG, MIG or SMAW with no preheat, interpass below 100 °C and low heat input to limit molybdenum segregation. C276, C-22, C-2000 and B-3 are used as welded; only heavy sections or the older B-2 need a post-weld anneal. Sulfur and lead embrittle nickel welds.
- Heat treatment
- Solution annealing only — about 1,120 °C for the C grades, 1,065 °C for Hastelloy B-3 and 1,175 °C for Hastelloy X — with a rapid quench. Nothing hardens; long holds between 650 and 1,000 °C precipitate molybdenum-rich phases that cost ductility and corrosion resistance, which is why Hastelloy C-4 and C-22 exist for parts that see heat after fabrication.
- Forming
- Ductile (40–60 % elongation) but stiff: bending and deep drawing take about 30 % more force than 316L with more springback and faster work hardening. Sheet and plate cold-form to normal stainless radii, annealed between severe stages. Hastelloy X sheet forms particularly well, which is why it dominates combustor fabrication.
Other nickel alloy series
Hastelloy Alloys — frequently asked
What is Hastelloy?
Hastelloy is the nickel-molybdenum family for wet corrosion: 13–30 % molybdenum, 0–23 % chromium and a few percent tungsten in a nickel base, with carbon and silicon held so low that the alloys stay corrosion-resistant as welded. The C grades (Hastelloy C276, Hastelloy C-22, Hastelloy C-2000) handle oxidizing and reducing media alike — wet chlorine, hypochlorite, hot contaminated sulfuric and hydrochloric acid, ferric and cupric chlorides; the B grades (Hastelloy B-3) take pure hydrochloric and sulfuric acid to boiling; Hastelloy X is the high-temperature sheet alloy for combustors to 1,200 °C. Yield strength runs 300–400 MPa annealed with 40–60 % elongation.
Which grade of Hastelloy should I use?
Hastelloy C276 when the chemistry is unknown, mixed or contaminated: 16 % Cr, 16 % Mo and 4 % W give the widest tolerance of chlorides, oxidizers and reducers of any common alloy, and every chemical plant and fabricator knows it. Hastelloy C-22 raises chromium to 22 % for oxidizing media (nitric acid, wet chlorine, ferric chloride) and better stability in the weld zone, and its filler (ERNiCrMo-10) joins any of the C alloys. Hastelloy C-2000 adds 1.6 % copper to cover reducing sulfuric acid as well, the most versatile of the group; Alloy 59 is the copper-free equivalent on European drawings. Hastelloy B-3 (28.5 % Mo, almost no chromium) is the hydrochloric-acid alloy — any concentration, to boiling — provided the acid carries no dissolved oxygen or ferric ions; it replaced Hastelloy B-2 by fixing the embrittlement that made B-2 hard to fabricate. Hastelloy G-3 is the sour-gas and phosphoric-acid grade. Hastelloy X (22 % Cr, 9 % Mo, 18 % Fe) is for combustor cans, transition ducts and furnace parts, not wet corrosion. Castings are CW-12MW and CW2M for the C alloys, CX2MW for C-22 chemistry and N7M for B-type service.
Which grade of Hastelloy is the strongest?
ENiCrMo-3 has the highest yield strength in the series at 520 MPa; ENiCrMo-4 follows at 505 MPa. Values are for each grade's default condition.
Which grade of Hastelloy is easiest to machine?
CU5MCuC (machinability poor, 28/100), then Alloy 30 (25/100).
Hastelloy C276 or C-22?
Both cover the same territory and are often interchangeable. C276 has more molybdenum and tungsten and is a little better in reducing and mixed acids and hot chloride pitting; C-22 has more chromium and is better in oxidizing media — nitric acid, wet chlorine, ferric and cupric chlorides, hypochlorite — and more stable in the weld heat-affected zone, so heavy weldments and parts that see 650–1,000 °C after fabrication favour it. Well-characterized reducing process: C276. Oxidizing, unknown or heavily welded: C-22. C-2000 when both conditions occur in the same vessel.
When is Hastelloy B-3 the right choice?
When the acid is hydrochloric or sulfuric, hot and pure. B-3 is 65 % nickel and 28.5 % molybdenum with almost no chromium, so it resists reducing acids that dissolve every chromium-bearing alloy — HCl at all concentrations to boiling is its home. The same lack of chromium means it fails quickly in anything oxidizing: aeration, ferric or cupric ions at parts-per-million levels, nitric acid or wet chlorine. B-3 replaced B-2 because it stays ductile through welding and heat treatment where B-2 embrittled by ordering at 600–850 °C.