Project Description
Hastelloy B-2 (UNS N10665 / W. Nr. 2.4617 / NiMo28) is the second-generation nickel-molybdenum solid-solution alloy, developed specifically to overcome the thermal-stability weaknesses of the original Hastelloy B (N10001). By restricting iron to ≤ 2.0 % and chromium to ≤ 1.0 %, the alloy effectively suppresses the formation of β-phase Ni₄Mo precipitates, delivering a microstructure that remains stable after cooling through the critical 700–870 °C sensitisation range. With molybdenum maintained at 26–30 %, B-2 provides exceptional resistance to hydrochloric acid at all concentrations and temperatures—including the boiling point—as well as to pure sulfuric, phosphoric, acetic, and hydrofluoric acids in reducing conditions. Its virtual immunity to chloride-induced SCC makes it indispensable for acid stimulation services, HF alkylation units, and sour-gas absorption columns in oil and gas processing. SHUNFU METAL supplies N10665 bar from VIM+VAR-refined heats, solution-annealed at 1,150 °C ± 15 °C with rapid water quench, verified by hardness testing and 100 % ultrasonic inspection, with EN 10204 3.1 / 3.2 MTR on every shipment.
Hastelloy B-2 / N10665 — Introduction
Hastelloy B-2 is the refined successor to the original Hastelloy B (N10001), engineered through tighter compositional controls to solve the most critical limitation of its predecessor: susceptibility to Ni₄Mo β-phase embrittlement during welding and slow cooling. By reducing iron from ≤ 4 % to ≤ 2 % and chromium to ≤ 1 %, B-2 maintains a single-phase FCC austenitic matrix through the hazardous 700–870 °C range, enabling safe use in as-welded components without mandatory post-weld annealing. The ultra-low carbon (≤ 0.02 %) and silicon (≤ 0.10 %) controls further minimise grain-boundary carbide and silicide precipitation in heat-affected zones, ensuring weld-zone corrosion resistance equals that of the parent metal.
SHUNFU METAL melts B-2 billets under full vacuum (VIM) with precisely controlled Mo addition to hit the 26–30 % target window, then re-melts by VAR to eliminate macrosegregation and radial composition gradients—critical for large-diameter forged bars used in high-pressure pump shafts and reactor internals. Hot working at 1,020–1,150 °C is followed immediately by solution annealing at 1,150 °C ± 15 °C and rapid water quench to lock in the corrosion-resistant single-phase structure. Each heat undergoes spectrometric composition verification, Brinell hardness check per ASTM E10, and 100 % ultrasonic inspection per ASTM E114. Intergranular corrosion (IGC) testing per ASTM A262 Practice E and third-party inspection (SGS / Bureau Veritas / TÜV) are available on request.
Equivalent Grades & Applicable Standards — Hastelloy B-2 N10665
| Standard Body | Designation | Applicable Specification / Form |
|---|---|---|
| ASTM / ASME | UNS N10665 | B335 / SB-335 (rod & bar), B333 / SB-333 (plate / sheet / strip), B622 / SB-622 (seamless pipe & tube), B619 / SB-619 (welded pipe), B626 / SB-626 (welded tube), B366 / SB-366 (fittings), B564 / SB-564 (forgings), B462 (forged fittings) |
| EN / DIN | 2.4617 / NiMo28 | DIN 17752 (bar & rod), DIN 17750 (plate / sheet / strip), DIN 17751 (seamless tube), DIN 17744 (wrought alloy designations) |
| AMS | AMS 5765 / AMS 5467 | AMS 5765 (bar, rod, wire — solution annealed); AMS 5467 (sheet, strip, plate) |
| BS (UK) | NA 13 | BS 3072 (sheet & plate), BS 3073 (strip), BS 3074 (seamless tube), BS 3075 (wire), BS 3076 (bar) |
| GB (China) | NS3203 / NS322 | GB/T 14992 (wrought nickel alloy designation), GB/T 15007 (bar), GB/T 14995 (plate) |
| GOST (Russia) | ХН65МВ (approximate) | Near-equivalent NiMo alloy; contains additional W not present in B-2; verify composition for critical applications |
| AWS (Welding) | ERNiMo-7 / ENiMo-7 | AWS A5.14 (filler metal), AWS A5.11 (welding electrode); low-heat-input GTAW recommended to minimise HAZ exposure time in 700–870 °C range |
| Trade Names | HASTELLOY® B-2 / Nicrofer® 6628 / Corronel® 220B | Same UNS N10665 / 2.4617 composition. Note: B-3 (N10675) is a further-improved grade with better thermal stability; not interchangeable without engineering review |
Oil & Gas Applications — N10665 Bar Components
- HCl acid pump impellers & shafts
- Acid injection valve bodies & stems
- Matrix acidizing nozzle bodies
- Coiled tubing BHA tool bars
- Acid mixing tank fittings & bars
- Reactor vessel internals
- HF acid settler bars & baffles
- Regeneration column packing supports
- HF stripper reboiler tubes & heads
- Acid rundown line fittings
- Amine absorber tray support bars
- H₂S scrubber column internals
- Sour water stripper agitator shafts
- Acid gas compressor valve bars
- Sour gas separator vessel clips
- HDS unit feed/effluent heat exchanger baffles
- FGD quencher spray nozzles & supports
- Phosphoric acid reactor stirrer shafts
- Sulfuric acid alkylation piping bars
- Crude unit overhead condenser tube sheets
⚠ Important Limitation: Hastelloy B-2 must NOT be used in environments containing oxidising contaminants such as ferric (Fe³⁺) or cupric (Cu²⁺) ions, dissolved oxygen, or nitric acid. Even trace levels (ppm) cause rapid, catastrophic corrosion. For mixed oxidising/reducing environments, specify Hastelloy C-276 (N10276) or C-2000 (N06200).
Supply Forms & Size Range — N10665 Bar
| Form | Size Range | Standard / Condition |
|---|---|---|
| Hot-Rolled Round Bar | Ø 6 – 250 mm | ASTM B335, solution-annealed + pickled, L = 1,000–6,000 mm |
| Cold-Drawn Round Bar | Ø 3 – 80 mm | ASTM B335, bright-drawn + solution-annealed, tight tolerance h9/h11 |
| Hot-Rolled Flat Bar | T: 6–100 mm × W: 20–350 mm | ASTM B335, solution-annealed, L = 1,000–4,000 mm |
| Forged Round Bar | Ø 80 – 700 mm | ASTM B564 / B564M, VIM+VAR melt, solution-annealed + UT per ASTM A388 |
| Forged Flat Bar / Block | T: 50–300 mm × W: up to 800 mm | ASTM B564, rough-machined or as-forged, custom lengths to 2,500 mm |
| Hexagon Bar | AF 6 – 70 mm | ASTM B335, solution-annealed, for valve stems & fastener pre-forms |
| Turned & Ground Bar (TGP) | Ø 10 – 200 mm | ASTM B335, centreless-ground to h6/h8 tolerance, Ra ≤ 0.8 µm; ready for CNC machining |
Non-standard dimensions, custom lengths, and semi-finished machined blanks available on request. Surface finish options: black / pickled / ground / polished. Mill test reports issued per EN 10204 3.1 (standard) or 3.2 (witnessed by third-party inspector).
Chemical Composition — Hastelloy B-2 per ASTM B335 (UNS N10665)
| Element | Ni | Mo | Fe | Cr | Co | Mn | C | Si | V | P | S |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Min (%) | Bal. | 26.0 | — | — | — | — | — | — | — | — | — |
| Max (%) | — | 30.0 | 2.0 | 1.0 | 1.0 | 1.0 | 0.02 | 0.10 | 0.20 | 0.04 | 0.03 |
Fe ≤ 2.0 % and Cr ≤ 1.0 % (highlighted) are the critical improvements over Hastelloy B (N10001), which allowed Fe up to 4–6 % and Cr up to 1.5 %; these tighter limits are the key to suppressing β-phase Ni₄Mo embrittlement. SHUNFU METAL verifies all eleven elements by optical emission spectrometry (OES) on each melt, with a certificate of conformance to UNS N10665 issued for every heat.
Mechanical Properties — Hastelloy B-2 N10665
| Condition | Tensile Strength | 0.2% Yield Strength | Elongation | Hardness | Basis |
|---|---|---|---|---|---|
| Annealed (Solution-Treated) 1,150 °C / rapid water quench |
≥ 690 MPa (100 ksi) |
≥ 310 MPa (45 ksi) |
≥ 40 % | ≤ 99 HRB ≤ 241 HB |
ASTM B335 minimum; standard delivery condition |
| Hot-Finished Bar As-forged + solution-annealed |
≥ 690 MPa | ≥ 310 MPa | ≥ 40 % | ≤ 99 HRB | ASTM B335; same minimums, higher typical values due to finer grain |
| Cold-Drawn Bar Cold-drawn (not final-annealed) |
760–900 MPa (typical) |
480–690 MPa (typical) |
20–35 % | 95–105 HRB | Work-hardened state; final annealing restores full corrosion resistance |
| Typical Annealed (Actual) SHUNFU METAL heat data |
760–830 MPa (110–120 ksi) |
350–420 MPa (51–61 ksi) |
45–55 % | 82–92 HRB | Production test results from VIM+VAR heats; reported in 3.1/3.2 MTR |
B-2 vs B comparison: B-2 (N10665) delivers the same tensile/yield minima as B (N10001) but with superior thermal-cycle stability. The key advance is not higher room-temperature strength but the elimination of age-embrittlement risk during processing and service. For elevated-temperature pressure design, consult ASME BPVC Section II Part D for SB-335 allowable stress values. SHUNFU METAL issues full tensile + hardness test reports with every lot, conforming to ASTM E8/E18.