Hastelloy / UNS N10665
Hastelloy® B-2 is a nickel-molybdenum alloy for strongly reducing environments such as hydrochloric acid at all concentrations and temperatures. It must not be used where oxidising species are present.
- UNS N10665
- W.Nr. 2.4617
- Spec ASTM B333
- Density 9.22 g/cm³
Also known as / equivalents
| System | Designation |
|---|---|
| UNS | N10665 |
| W.Nr. | 2.4617 |
| EN | NiMo28 |
| Also known as | B2, B-2, Alloy B-2, 2.4617, NiMo28 |
Chemical composition
| Element | Min % | Max % |
|---|---|---|
| Ni | Bal. | — |
| Mo | 26.0 | 30.0 |
| Fe | — | 2.0 |
| Cr | — | 1.0 |
| Co | — | 1.0 |
| C | — | 0.02 |
| Si | — | 0.10 |
| Mn | — | 1.0 |
| P | — | 0.04 |
| S | — | 0.03 |
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength (min) | 760 MPa (110.2 ksi) |
| Yield strength, 0.2% offset (min) | 350 MPa (50.8 ksi) |
| Elongation in 50 mm (min) | 40 % |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 9.22 g/cm³ | 0.333 lb/in³ |
| Magnetic response | Non-magnetic | — |
Available forms & specifications
| Form | Specification | Size range |
|---|---|---|
| Sheets & plates | ASTM B575 / ASME SB575 (C-family), ASTM B333 (B-family) | 0.3 mm – 6 mm |
| Welded pipe | ASTM B619 | 1/8" – 24" NB |
| Seamless pipe & tube | ASTM B622 | 1/8" – 24" NB |
| Welded tube | ASTM B626 | 1/8" – 24" NB |
| Bars & rods | ASTM B574 (C-family), B335 (B-family) | 3 mm – 500 mm |
| Flanges & forgings | ASTM B564 / B462 | 1/2" – 48" NB (larger on request) |
| Buttweld fittings | ASTM B366 | 1/2" – 48" NB |
Corrosion & temperature resistance
The C-family resists pitting, crevice corrosion and stress-corrosion cracking in chlorides, wet chlorine, hypochlorite and mixed acids. The B-family is for pure reducing acids (HCl, H₂SO₄) and must not be used where ferric or cupric ions or oxidisers are present.
Applications
Hastelloy® B-2: HCl, sulphuric and phosphoric acid service. Chemical reactors, scrubbers and flue-gas desulphurisation, pulp and paper bleaching, pharmaceutical process equipment and acid handling.
Hastelloy® B-2 vs Hastelloy® B-3
| Hastelloy® B-2 | Hastelloy® B-3 | |
|---|---|---|
| UNS | N10665 | N10675 |
| Key property | Hydrochloric-acid resistant | More thermally stable B-alloy |
| Typical use | HCl, sulphuric and phosphoric acid service | HCl processing, acetic acid, vessels |
| Cr (wt %) | ≤ 1.0 | 1.0–3.0 |
| Ni (wt %) | Bal. | 65.0 |
| Mo (wt %) | 26.0–30.0 | 27.0–32.0 |
| C (wt %) | ≤ 0.02 | ≤ 0.01 |
| Tensile / yield (min, MPa) | 760 / 350 | 760 / 350 |
Frequently asked questions
What is the UNS number of Hastelloy® B-2?
Hastelloy® B-2 is designated UNS N10665 (W.Nr. 2.4617, EN NiMo28).
What is Hastelloy® B-2 used for?
Hydrochloric-acid resistant. Typical uses: hcl, sulphuric and phosphoric acid service.
Is Hastelloy® B-2 magnetic?
Non-magnetic.
In which forms can I buy Hastelloy® B-2 from Rajkamal Metals?
Coils & Strips, Sheets & Plates, Pipes & Tubes, Round Bars & Rods, Flanges, Buttweld Fittings, Socket Weld & Threaded Fittings, Fasteners, Ferrule / Instrumentation Fittings. Sizes as per standard; other sizes on request.
Do you supply a Mill Test Certificate with Hastelloy® B-2?
Yes. Actual values are given in the Mill Test Certificate (EN 10204 3.1) supplied with each order.
What is the difference between Hastelloy® B-2 and Hastelloy® B-3?
Hastelloy® B-2: hydrochloric-acid resistant. Hastelloy® B-3: more thermally stable b-alloy. See the comparison table on this page.
Last updated: 30 October 2026. Grade names identify the supply range; designations are not engineering equivalents. Availability, make, origin and documentation are confirmed at quotation.
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