1. Product Overview
Hastelloy B3 is an advanced improved variant of the Hastelloy B series, developed to address the limitations of Hastelloy B2 in long-term cyclic high-temperature service and complex reductive media. As a nickel-molybdenum alloy, it retains the core advantage of excellent resistance to reductive acids (e.g., hydrochloric acid, formic acid) while achieving breakthroughs in three key areas: enhanced intergranular corrosion resistance (even after repeated heating-cooling cycles), superior stress corrosion cracking (SCC) resistance in chloride-containing reductive environments, and better tolerance to trace harmful impurities (e.g., sulfur, phosphorus) in media. With stable mechanical properties at 20°C-1300°C and good processability (cold/hot rolling, forging, precision welding), it is the preferred material for ultra-harsh reductive scenarios such as high-temperature cyclic hydrochloric acid processing and high-pressure hydrogenation with impurity fluctuations.
2. Chemical Composition
Hastelloy B3 strictly complies with international standards (e.g., ASTM B333/B335/B336 for B3 grade). Its chemical composition is optimized for improved corrosion resistance and thermal stability, with stricter control of trace elements compared to Hastelloy B2:
| Element (Chemical Symbol) | Content Range (Mass Fraction) |
| Ni | ≥65% |
| Mo | 27.0%-30.0% |
| Fe | 2.0%-5.0% |
| C | ≤0.003% |
| Si | ≤0.05% |
| P | ≤0.015% |
| S | ≤0.005% |
| Co | ≤0.2% |
3. Physical Properties
Hastelloy B3 exhibits enhanced thermal stability and mechanical consistency compared to Hastelloy B2, with physical properties finely tuned for cyclic high-temperature service. Key parameters (test conditions per ASTM standards) are listed below:
| Property Item | Value | Test Condition |
| Density | 9.21 g/cm³ | 20°C |
| Melting Range | 1320-1380°C | - |
| Thermal Conductivity | 11.7 W/(m·K) | 20°C |
| Thermal Conductivity | 14.6 W/(m·K) | 500°C |
| Specific Heat Capacity | 432 J/(kg·K) | 20-100°C |
| Coefficient of Linear Expansion | 11.1 ×10⁻⁶/°C | Room Temperature-100°C |
| Coefficient of Linear Expansion | 13.4 ×10⁻⁶/°C | Room Temperature-500°C |
| Electrical Resistivity | 1.37 ×10⁻⁶ Ω·m | 20°C |
| Elastic Modulus | 209 GPa | 20°C |
4. Usage Precautions
Oxidizing Media Avoidance: Similar to other B-series alloys, Hastelloy B3 has limited resistance to strong oxidizing media (e.g., concentrated nitric acid, chromate solutions). Even trace oxidizing ions (e.g., Cr⁶⁺) can accelerate corrosion—pre-treat media with reducing agents (e.g., sodium sulfite) if needed.
Welding & Heat Treatment: Use argon with purity ≥99.995% for full weld protection (including root pass) to prevent weld oxidation. For thick-walled components (>20mm), post-weld solution heat treatment (1100-1150°C, water quenching) is recommended to eliminate residual stress and further enhance intergranular corrosion resistance.
Storage & Contamination Control: Store in a sealed, chloride-free warehouse to avoid surface pitting from ambient moisture. Avoid contact with carbon steel during transportation (to prevent iron contamination, which may reduce corrosion resistance in reductive acids).
Cyclic Temperature Management: When used in cyclic heating-cooling scenarios, control the temperature rise/fall rate ≤300°C/h to avoid thermal fatigue damage—especially for thin-walled pipes (thickness <5mm).
5. Selection Recommendations
Cyclic High-Temperature Reductive Scenarios: Prioritize Hastelloy B3 over B2 for equipment with repeated heating-cooling cycles (e.g., batch reactors, cyclic evaporators), as it resists intergranular corrosion better under thermal cycling.
Impurity-Containing Reductive Media: For reductive acids with trace sulfur, phosphorus, or heavy metal impurities (e.g., industrial-grade hydrochloric acid), B3 is more tolerant than B2—reducing the risk of localized corrosion.
High-Stress Applications: In high-pressure reductive systems (e.g., high-pressure hydrogenation pipes) requiring resistance to stress corrosion cracking (SCC), select B3 rods/forgings to leverage its superior SCC resistance.
Cost vs. Performance Balance: B3 has a slightly higher cost than B2 but lower than C276. For simple static reductive scenarios (e.g., low-temperature hydrochloric acid storage tanks), B2 remains cost-effective; reserve B3 for cyclic, impurity-rich, or high-stress reductive 工况.
