1. Basic Information
- Grade: Hastelloy B2 / B3
- UNS:
- B2: N10665
- B3: N10675
- W.Nr.:
- B2: 2.4617
- B3: 2.4600
- Alloy Type: Nickel‑Molybdenum (Ni‑Mo) austenitic corrosion‑resistant alloy
- Key Features:
- Ultra‑high resistance to pure reducing acids (especially HCl)
- Excellent resistance to pitting, crevice corrosion and stress corrosion cracking
- B3 has significantly improved thermal stability compared to B2
2. Chemical Composition (wt%, typical)
Hastelloy B2 (N10665)
- Ni: Balance
- Mo: 26.0 – 30.0%
- Fe: ≤ 2.0%
- Cr: ≤ 1.0%
- Co: ≤ 1.0%
- Mn: ≤ 1.0%
- Si: ≤ 0.08%
- C: ≤ 0.01%
Hastelloy B3 (N10675)
- Ni: Balance
- Mo: 26.0 – 30.0%
- Fe: 1.0 – 3.0%
- Cr: ≤ 1.0%
- Co: ≤ 3.0%
- Mn: ≤ 1.0%
- Si: ≤ 0.08%
- C: ≤ 0.01%
3. Mechanical Properties (Annealed Condition)
| Property | Hastelloy B2 | Hastelloy B3 |
|---|---|---|
| Tensile Strength | ≥ 725 MPa | ≥ 760 MPa |
| Yield Strength (0.2% offset) | ≥ 315 MPa | ≥ 345 MPa |
| Elongation | ≥ 40% | ≥ 40% |
| Hardness (HB) | ≤ 210 | ≤ 210 |
| Modulus of Elasticity | ~210 GPa | ~210 GPa |
4. Corrosion Resistance
- Excellent corrosion resistance in pure reducing environments:
- Concentrated hydrochloric acid (HCl)
- Wet hydrogen chloride gas
- Sulfuric acid (non‑oxidizing)
- Phosphoric acid, acetic acid, and other organic acids
- Excellent resistance to pitting and crevice corrosion.
- High resistance to chloride stress corrosion cracking (SCC).
- B3 > B2:
- Much better thermal stability
- Less prone to intergranular corrosion after welding or high‑temperature exposure
- Not recommended for oxidizing media (nitric acid, ferric/cupric salts).
5. Physical Properties
- Density: 9.22 g/cm³
- Melting Range: 1370 – 1418 °C
- Thermal Expansion (20–100°C): ~10.8 × 10⁻⁶ /°C
- Thermal Conductivity: ~8.7 W/(m·K)
- Magnetism: Non‑magnetic
6. Fabrication & Welding
- Heat Treatment:Solution annealing at 1060–1080°C, followed by rapid water quenching.
- Welding:Good weldability.Recommended filler metal: ERNiMo‑2 (for B2 / B3).
- B3 requires no post‑weld heat treatment for corrosion resistance.
- Good cold formability; moderate work hardening.
7. Typical Applications
- Chemical reactors and piping for hydrochloric acid
- HCl gas scrubbing systems
- Pickling systems in steel and metal processing
- Pharmaceutical production equipment
- Sulfuric acid alkylation units
- Oil & gas production in sour, reducing environments
- Polysilicon and chemical processing equipment
8. Short Description (for Post List Excerpt)
Widely used in chemical processing, acid production, and pharmaceutical equipment.
Hastelloy B2 / B3 (UNS N10665 / N10675)
Nickel‑molybdenum alloys designed for extreme reducing environments, especially concentrated hydrochloric acid.
B3 offers improved thermal stability and better post‑weld corrosion resistance than B2.