Excellent Corrosion Resistance of Hastelloy B3
Hastelloy B3 is a nickel-molybdenum alloy engineered for superior performance in highly reducing environments. It offers exceptional resistance to hydrochloric acid across all concentrations and temperatures, as well as to other strong reducing agents such as hydrobromic and sulfuric acids. Compared to B2, Hastelloy B3 has improved thermal stability and resistance to stress corrosion cracking and knife-line attack.
This article introduces the composition, properties, and typical applications of Hastelloy B3, helping engineers make better material decisions for aggressive chemical environments.
What is Hastelloy B3?
Hastelloy B3 (UNS N10675) is an advanced corrosion-resistant alloy designed to address the shortcomings of previous Hastelloy B grades, particularly thermal instability. It is highly resistant to pure hydrochloric acid, both hot and cold, and demonstrates improved fabricability and structural integrity in harsh process conditions.
Hastelloy B3 Equivalent Grades
| Standard / System | Equivalent Designation |
| UNS | N10675 |
| ASTM / ASME | ASTM B335, B622, B619, B366 |
| EN / DIN | 2.46 |
| ISO | NiMo29Cr |
| JIS | NW10675 |
Hastelloy B3 Chemical Composition
| Element | Content (%) |
| Nickel (Ni) | Balance |
| Molybdenum (Mo) | 28.5 – 30.5 |
| Iron (Fe) | ≤ 1.5 |
| Chromium (Cr) | ≤ 1.0 |
| Cobalt (Co) | ≤ 3.0 |
| Carbon (C) | ≤ 0.01 |
| Manganese (Mn) | ≤ 3.0 |
| Silicon (Si) | ≤ 0.10 |
| Sulfur (S) | ≤ 0.01 |
Hastelloy B3 Mechanical Properties
| Property | Typical Value |
| Tensile Strength | 760 – 830 MPa |
| Yield Strength | ≥ 320 MPa |
| Elongation | ≥ 40% |
| Hardness (HBW) | ~200 |
Hastelloy B3 Physical Properties
| Property | Value |
| Density | 9.22 g/cm³ |
| Melting Point | 1370 – 1418 °C |
| Thermal Conductivity | ~10 W/m·K |
| Electrical Resistivity | ~1.1 µΩ·m |
| Modulus of Elasticity | ~200 GPa |
| Service Temperature Range | -196 °C to ~425 °C |
Applications of Hastelloy B3
- Hydrochloric Acid Systems: Tanks, piping, and reactors handling HCl at any concentration.
- Chemical Process Equipment: Vessels, heat exchangers, and reactors exposed to reducing agents.
- Pesticide and Dye Manufacturing: Resistant to aggressive organic chemicals and acids.
- Electronics Industry: Suitable for ultra-pure chemical handling systems.
- Pickling Equipment: Withstands severe acid mixtures and high temperatures.
Advantages of Hastelloy B3
- Outstanding resistance to hydrochloric acid, hydrobromic acid, sulfuric acid, and acetic acid.
- Improved thermal stability: Greater resistance to thermal decomposition than B2.
- Reduced sensitivity to knife-line attack and grain boundary precipitation.
- Better fabricability: Easier to form and weld compared to earlier Hastelloy B alloys.
- Excellent resistance to stress corrosion cracking under harsh chemical conditions.
Limitations of Hastelloy B3
- Not suitable for oxidizing environments (e.g., nitric acid or ferric chloride).
- Relatively expensive: High cost due to high molybdenum and nickel content.
- May require special handling during fabrication to maintain corrosion resistance.
- Work hardens quickly, requiring careful machining and forming techniques.
Hastelloy B3 vs Other Alloys
| Feature | B2 | B3 | C276 |
| HCl Resistance | Excellent | Excellent | Good |
| Thermal Stability | Moderate | High | Very High |
| Stress Corrosion Cracking | Moderate | Excellent | Excellent |
| Workability | Good | Improved | Good |
| Oxidizer Resistance | Poor | Poor | Excellent |
| Cost | High | Very High | Very High |
Summary
This article highlights Hastelloy B3 as an advanced solution for extreme reducing acid environments, particularly hydrochloric acid. With enhanced thermal stability and corrosion resistance over previous grades, B3 is ideal for chemical processing, electronics, and pharmaceutical applications.
MT.BOLTS supplies precision components and fasteners in Hastelloy B3, tailored for high-performance use in chemical and industrial systems. Contact us today to request more information or a quote.
