Hastelloy B-2 · UNS N10665 · W. Nr. 2.4617
Hastelloy B-2 (N10665): composition, properties, fittings and flanges
Hastelloy B-2 (N10665, W. Nr. 2.4617) is Nickel-molybdenum alloy for reducing acid service. Hastelloy B-2 is specified at Nickel Balance, Molybdenum 26.0 - 30.0, Chromium 1.00 max. Hastelloy B-2 is the reference alloy for hot hydrochloric and sulphuric acid: with 28 % molybdenum and almost no chromium it resists reducing acids…
- UNS
- N10665
- W. Nr.
- 2.4617
- Density
- 9.22 g/cm³ (0.333 lb/in³)
- Key strength
- 690 MPa / 100 ksi
Identification and standards
| Short form | Hastelloy B-2 · UNS N10665 · W. Nr. 2.4617 |
|---|---|
| Classification | Nickel-molybdenum alloy for reducing acid service |
| UNS | N10665 |
| Werkstoff number | 2.4617 |
| Material family | Hastelloy Alloys |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Nickel (Ni) | Balance | Matrix |
| Molybdenum (Mo) | 26.0 - 30.0 | Resistance to reducing acids |
| Iron (Fe) | 2.00 max | Residual |
| Chromium (Cr) | 1.00 max | Deliberately low - oxidisers attack B-2 |
| Carbon (C) | 0.02 max | Prevents carbide precipitation |
| Silicon (Si) | 0.10 max | Controlled for hot ductility |
| Manganese (Mn) | 1.00 max | - |
| Phosphorus (P) | 0.040 max | - |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min (annealed) | 690 MPa / 100 ksi |
|---|---|
| 0.2 % yield strength, min | 310 MPa / 45 ksi |
| Elongation in 2 in, min | 40 % |
| Typical hardness, annealed | 180 - 230 HB |
| Avoid service with | Oxidising salts, ferric and cupric ions, nitric acid |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 9.22 g/cm³ (0.333 lb/in³) |
|---|---|
| Melting range | 1330 - 1380 °C (2425 - 2515 °F) |
| Modulus of elasticity | 217 GPa (31.5 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 11.1 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 10.3 µm/m·°C |
| Specific heat capacity | 389 J/kg·K |
Specifications by product form
| Forgings & flanges | ASTM B564 / ASME SB-564 (UNS N10665) |
|---|---|
| Butt weld fittings | ASTM B366 / ASME SB-366 (WP grade to order) |
| Seamless pipe & tube | ASTM B622 / B619 / ASME SB-622 |
| Plate / sheet / strip | ASTM B333 / ASME SB-333 |
| Bar / rod | ASTM B335 / ASME SB-335 |
| Welding consumables | ERNiMo-7 or matching B-2 filler |
| UNS / EN / China | UNS N10665 · W. Nr. 2.4617 · GB NS322 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Forged flanges blanks and finished flanges to ASME B16.5, B16.47 Series A/B and B16.36
- Butt weld elbows, tees, reducers, caps and stub ends to ASME B16.9 and MSS SP-43
- Seamless pipe and tube to the applicable ASTM / ASME pipe specification
- Forged rings, discs and hubs machined to your drawing
Typical applications
- Hydrochloric acid pickling, regeneration and distillation plant
- Acetic acid, alkylation and catalyst recovery units
- Sulphuric acid service below the oxidising threshold
- Reactors, columns and piping handling reducing halides
Welding, forming and machining
- Welding
- Weld with matching ERNiMo-7 filler. Keep carbon and silicon low in the weld metal and avoid post-weld heat treatment in the 540 - 760 °C range, where the ordered Ni4Mo phase embrittles the alloy.
- Heat treatment
- Solution anneal at 1065 °C minimum and water quench. Never slow cool - B-2 loses ductility if it dwells between 540 and 760 °C.
- Hot and cold forming
- Hot work in the range stated by the mill for this grade, then re-solution or re-age before final machining so that the delivered condition matches the certificate.
- Machining
- Machine with sharp carbide or high-speed steel tooling, positive rake, constant feed and ample coolant. Never dwell - the surface work-hardens quickly.
Buy Hastelloy B-2 from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.