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1. Basic Introduction
Alloy B-2 (commercial name Hastelloy B-2) is a nickel-molybdenum wrought corrosion-resistant alloy.
UNS N10665: Standard designation for modern Hastelloy B-2
UNS N10001: Old grade Hastelloy B (B-1), the predecessor of B-2, now largely replaced
German standard: 2.4617
2. Alloy B-2 Chemical Composition (wt%)
| Element | Specification Range |
| Nickel (Ni) | Remainder |
| Chromium (Cr) | ≤ 1.0 |
| Molybdenum (Mo) | 26.0 ~ 30.0 |
| Iron (Fe) | ≤ 2.0 |
| Cobalt (Co) | ≤ 1.0 |
| Manganese (Mn) | ≤ 1.0 |
| Silicon (Si) | ≤ 0.10 |
| Carbon (C) | ≤ 0.02 |
| Phosphorus (P) | ≤ 0.04 |
| Sulfur (S) | ≤ 0.03 |
3.2.4617 Key Properties
Superior performance: Excellent resistance to reducing acids, and withstands hydrochloric acid of all concentrations even at boiling point.
Good performance: Maintains stable corrosion resistance in dilute sulfuric acid, phosphoric acid, formic acid and acetic acid.
High resistance: Effectively resists chloride-induced stress corrosion cracking.
Limitation: Not applicable for service in oxidizing environments, such as nitric acid, ferric ion and cupric ion media.
4. Physical Properties Of UNS N10665
| Item | Specification |
| Density | 9.24 g/cm³ |
| Melting Range | 1330 ~ 1380 °C |
| Thermal Conductivity (20 °C) | 10.8 ~ 11.2 W/(m·K) |
| Specific Heat Capacity (20 °C) | 407 J/(kg·K) |
| Mean Coefficient of Linear Expansion | 11.2 × 10⁻⁶ /°C (20~100 °C) |
| Electrical Resistivity (20 °C) | 1.35 μΩ·m |
| Elastic Modulus (20 °C) | 210 GPa |
| Magnetism | Non-magnetic |
5. Mechanical Properties (Solution Annealed) of Hastelloy B-2
| Item | Requirement |
| Tensile Strength | ≥ 690 MPa |
| Yield Strength (0.2% Offset) | ≥ 310 MPa |
| Elongation | ≥ 40 % |
| Brinell Hardness | ≤ 240 HB |
6. Heat Treatment
Solution Annealing
Temperature Range: 1065–1120 °C
Soaking Time: 15–30 minutes per 25 mm of section thickness
Cooling Method: Rapid cooling (water quenching or forced air cooling)
Purpose: To dissolve precipitated phases, eliminate stresses, and restore optimal corrosion resistance and mechanical properties.
Note: Prolonged exposure in the temperature range of 425–870 °C must be avoided to prevent the formation of brittle intermetallic phases, which can cause embrittlement and intergranular corrosion.
Post-Weld Treatment
Service Condition: Alloy B-2 can be used in the as-welded condition without the need for post-weld heat treatment.
Stress Relief (If Required): Re-solution annealing at 1065–1120 °C followed by rapid cooling is recommended.
Prohibited Operations
Avoid long-term exposure at 425–870 °C, as this leads to the precipitation of detrimental phases (e.g., Ni₄Mo), resulting in brittleness and reduced corrosion resistance.
Age hardening is not applicable for this solution-strengthened alloy.
7. Workability
Cold Working: Suitable for conventional cold working processes such as cold rolling, cold drawing, stamping, and bending; however, the work hardening rate is higher than that of stainless steel, so intermediate annealing is required.
Hot Working: The hot working temperature range is 900–1200°C; the final working temperature should not be lower than 900°C; solution annealing is required after processing.
Welding: Can be welded using TIG, MIG, and shielded metal arc welding (SMAW) methods. The use of compatible ERNiMo-7 welding wire and ENiMo-7 welding rods is recommended. During welding, heat input should be controlled to avoid prolonged exposure to the sensitive temperature range.
8. Recommended Applications
Chemical industry: Hydrochloric acid production, pickling systems, acetic acid reactors, heat exchangers and piping.
Petrochemical industry: Sour service environments, flue gas desulfurization systems.
Pharmaceutical & light industry: Equipment in contact with strong reducing process media.
C&N offers a wide range of products made from ALLOY-B, including valves, pumps, fasteners (nuts, bolts, washers, and anchor rods), and machine components.
Contact us for more information and a quote!
