1. Product Overview
Hastelloy B2 is an improved low-carbon variant of Hastelloy B, belonging to the nickel-molybdenum corrosion-resistant alloy family. With nickel as the matrix, optimized molybdenum content, and ultra-low carbon design, it addresses the potential intergranular corrosion risk of Hastelloy B caused by carbide precipitation at high temperatures. This alloy retains excellent corrosion resistance to reductive acids (e.g., hydrochloric acid, formic acid) and exhibits enhanced thermal stability—maintaining stable mechanical properties and corrosion resistance even in long-term service at 200°C-1250°C. It also features good processability (cold rolling, hot rolling, forging, welding) and is widely used in harsh reductive environments requiring long-term high-temperature stability, such as advanced chemical processing and high-temperature hydrogenation systems.
2. Chemical Composition
The chemical composition of Hastelloy B2 strictly complies with international standards (e.g., ASTM B333/B335/B336 for B2 grade). Its typical element content range, distinguished by ultra-low carbon and optimized alloy ratios, is shown below:
| Element (Chemical Symbol) | Content Range (Mass Fraction) |
| Ni | ≥65% |
| Mo | 26%-30% |
| Fe | 2%-6% |
| C | ≤0.005% |
| Si | ≤0.1% |
| P | ≤0.02% |
| S | ≤0.01% |
3. Physical Properties
Hastelloy B2 maintains stable physical properties at room temperature and high temperatures, with slight optimizations in thermal stability compared to Hastelloy B. Key parameters (test conditions refer to ASTM standards) are listed below:
| Property Item | Value | Test Condition |
| Density | 9.20 g/cm³ | 20°C |
| Melting Range | 1325-1375°C | - |
| Thermal Conductivity | 11.6 W/(m·K) | 20°C |
| Thermal Conductivity | 14.3 W/(m·K) | 500°C |
| Specific Heat Capacity | 430 J/(kg·K) | 20-100°C |
| Coefficient of Linear Expansion | 11.0 ×10⁻⁶/°C | Room Temperature-100°C |
| Coefficient of Linear Expansion | 13.3 ×10⁻⁶/°C | Room Temperature-500°C |
| Electrical Resistivity | 1.36 ×10⁻⁶ Ω·m | 20°C |
| Elastic Modulus | 208 GPa | 20°C |
4. Usage Precautions
Oxidizing Environment Avoidance: Similar to Hastelloy B, Hastelloy B2 has poor corrosion resistance to strong oxidizing media (e.g., concentrated nitric acid, chromic acid). For media with trace oxidizing impurities (e.g., Fe³⁺, Cu²⁺), pre-removal via chemical precipitation is recommended to prevent pitting.
Welding Process Control: Use argon (purity ≥99.99%) for full protection during welding to avoid weld oxidation. Although Hastelloy B2 has low carbon content, post-weld cooling should be controlled (≤500°C/h) to prevent residual stress-induced microcracks; no solution heat treatment is required.
Storage and Transportation: Store in a dry, temperature-stable indoor warehouse (avoid temperature fluctuations >20°C/day) to prevent surface moisture condensation. Use shock-absorbing packaging (e.g., foam-lined wooden crates) during transportation to protect against mechanical damage.
5. Selection Recommendations
For reductive acid scenarios with long-term high-temperature service (≥800°C) or strict intergranular corrosion requirements (e.g., multi-cycle heating/cooling), Hastelloy B2 is preferred over Hastelloy B.
For high-pressure reductive systems (e.g., high-pressure formic acid reactors) or equipment requiring zero carbon 化物 precipitation (e.g., pharmaceutical sterile pipelines), select Hastelloy B2 plates/pipes to ensure material stability.
If the working condition involves both reductive media and occasional temperature spikes (≤1250°C), Hastelloy B2 forgings or thick-walled pipes are recommended for their superior thermal shock resistance; avoid using in mixed oxidizing-reductive media without professional evaluation.
