HASTELLOY B-2 Alloy
HASTELLOY B-2 Nickel-Molybdenum Alloy Supplier in Tunisia
HASTELLOY B-2 is a nickel-molybdenum alloy developed for applications requiring excellent corrosion resistance in strongly reducing chemical environments. Identified by UNS N10665 and commonly associated with Werkstoff Number 2.4617, this alloy is particularly suitable for chemical processing equipment exposed to hydrochloric acid and other compatible non-oxidizing acids.
With its high molybdenum content and low carbon and chromium levels, HASTELLOY B-2 offers excellent resistance to corrosion in suitable reducing environments. It also resists grain-boundary carbide precipitation in the weld heat-affected zone, making it suitable for many welded chemical-processing applications when the correct fabrication procedures are followed.
Emirerri Steel supplies industrial piping products and specialty alloy materials for chemical processing, petrochemical, oil and gas, power generation and other demanding industries. Product forms, dimensions, applicable standards and availability are confirmed according to project requirements.
Key Properties
- Material: Nickel-molybdenum alloy
- UNS Number: N10665
- Werkstoff Number: 2.4617
- Molybdenum Content: 26–30%
- Excellent resistance: Hydrochloric acid and selected reducing chemical environments
- Weldability: Suitable for many welded applications with appropriate procedures
- Corrosion performance: Good resistance to pitting and stress-corrosion cracking in compatible environments
- Typical industries: Chemical processing, petrochemical, acid production and industrial equipment manufacturing
HASTELLOY B-2 Chemical Composition
The following table presents commonly specified composition limits for HASTELLOY B-2. The applicable product standard and material test certificate should be checked before procurement.
| Element | Composition (%) |
|---|---|
| Nickel (Ni) | Balance |
| Molybdenum (Mo) | 26.0–30.0 |
| Iron (Fe) | 2.00 max. |
| Chromium (Cr) | 1.00 max. |
| Cobalt (Co) | 1.00 max. |
| Manganese (Mn) | 1.00 max. |
| Silicon (Si) | 0.10 max. |
| Carbon (C) | 0.02 max. |
| Phosphorus (P) | 0.040 max. |
| Sulfur (S) | 0.030 max. |
Molybdenum is the principal alloying element responsible for the material’s performance in reducing environments. Its relatively low chromium content is an important consideration when selecting this grade for chemical service.
HASTELLOY B-2 Mechanical Properties
The following values are indicative minimum values reported for certain solution-annealed product forms. Actual requirements depend on the applicable specification, dimensions and product type.
| Property | Indicative value |
|---|---|
| Tensile strength | 760 MPa minimum |
| 0.2% yield strength | 350 MPa minimum |
| Elongation | 40% minimum |
| Hardness | Depends on product form and specification |
These figures should not be treated as universal guaranteed values for every HASTELLOY B-2 product. Confirm the relevant ASTM or ASME specification and material test certificate for the ordered material.
HASTELLOY B-2 Physical Properties
| Property | Typical value |
|---|---|
| Density | Approximately 9.22 g/cm³ |
| Melting range | Approximately 1,330–1,380°C |
| Modulus of elasticity at room temperature | Approximately 217 GPa |
| Thermal conductivity | Approximately 11 W/m·K |
Physical values are indicative and may vary slightly between technical references and testing conditions.
Material Standards
HASTELLOY B-2 is covered by several ASTM and corresponding ASME specifications, depending on the product form.
| Product form | Common specification |
|---|---|
| Sheet, plate and strip | ASTM B333 / ASME SB-333 |
| Bars and rods | ASTM B335 / ASME SB-335 |
| Welding fittings | ASTM B366 / ASME SB-366 |
| Welded pipe | ASTM B619 / ASME SB-619 |
| Seamless pipe and tube | ASTM B622 / ASME SB-622 |
| Welded tube | ASTM B626 / ASME SB-626 |
| Forgings | ASTM B564 / ASME SB-564, where applicable |
Always confirm that the selected specification covers the required product form, manufacturing route, dimensions and inspection requirements.
Equivalent Grades
| Designation | Reference |
|---|---|
| UNS | N10665 |
| Werkstoff Number | 2.4617 |
| Alloy name | HASTELLOY B-2 |
| Material family | Nickel-molybdenum corrosion-resistant alloy |
These designations identify the same commonly referenced alloy. They should not be confused with other grades in the HASTELLOY B family or assumed to be interchangeable with other nickel alloys without a technical review.
Corrosion Resistance
HASTELLOY B-2 is designed primarily for reducing chemical environments. Its performance makes it a candidate material for equipment handling selected aggressive acids where conventional stainless steels may not provide adequate service life.
Hydrochloric Acid
The alloy is widely used in equipment handling hydrochloric acid across a broad range of concentrations and temperatures, subject to the actual process conditions and contamination levels.
Sulfuric Acid
HASTELLOY B-2 can be suitable for selected sulfuric acid applications. Its performance must be evaluated against acid concentration, temperature, aeration and other oxidizing contaminants.
Phosphoric and Acetic Acids
The alloy may be considered for compatible phosphoric acid, acetic acid and related chemical-processing environments. Process-specific corrosion data should guide material selection.
Important Corrosion Limitations
HASTELLOY B-2 has low chromium content and is not recommended for oxidizing environments or for service involving oxidizing salts such as ferric or cupric salts. Wet chlorine gas and hypochlorite bleach are also unsuitable environments for this grade.
The presence of iron or copper contamination in a hydrochloric acid system can create additional corrosion risks. A corrosion specialist should review the complete process chemistry before the alloy is selected.
Heat Resistance and Temperature Considerations
HASTELLOY B-2 is principally selected for corrosion resistance rather than unrestricted high-temperature service. Exposure to approximately 540–870°C can cause significant loss of ductility and should generally be avoided unless the specific service and material condition have been technically evaluated.
For equipment operating at elevated temperatures, consider the atmosphere, duration of exposure, thermal cycling, mechanical loading and applicable design code. Do not select HASTELLOY B-2 solely on the basis of its melting range.
Heat Treatment and Fabrication
HASTELLOY B-2 is normally supplied in an appropriate annealed condition according to the product specification. Solution heat treatment and rapid cooling may be required after certain fabrication operations to restore the desired material condition.
During forming, machining and fabrication, manufacturers should follow procedures suitable for nickel-based alloys. Tooling, cutting parameters, cleanliness and prevention of contamination are important to achieve the required surface quality and component performance.
Heat exposure during fabrication should be carefully controlled, particularly within temperature ranges associated with reduced ductility.
Welding
HASTELLOY B-2 can be welded using suitable procedures designed for nickel-molybdenum alloys. The selected filler metal, joint preparation, heat input and cleaning procedure should be compatible with the required service environment.
Recommended quality controls include:
Use of qualified welding procedures and welders.
Proper preparation and cleaning of joint surfaces.
Prevention of contamination from carbon steel and other metals.
Control of heat input and interpass temperature.
Appropriate inspection and testing based on project specifications.
Welding consumables and post-weld treatment should be selected by the responsible engineering team in accordance with the governing code and service conditions.
Applications
Chemical Processing Industry
Used in selected reactors, process vessels, heat exchangers, piping systems and equipment exposed to reducing acids.
Petrochemical Industry
Considered for specialized process equipment where the chemical environment is compatible with nickel-molybdenum alloys.
Acid Manufacturing
Suitable for certain hydrochloric acid and other compatible acid-handling systems following corrosion assessment.
Pharmaceutical and Fine Chemical Production
May be used in specialized chemical-processing equipment where corrosion resistance and material purity are important.
Industrial Piping and Equipment
Available product forms can support the manufacture of pipes, tubes, fittings, plates and other components when specified to the appropriate material standard.
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