Hangbo Alloy Group
Shanghai · Est. 2012
UNS N10675 / W.Nr. 2.4600 — Nickel-molybdenum alloy with superior resistance to hydrochloric acid at all concentrations and temperatures, plus improved thermal stability and fabricability over B-2.
Hastelloy B-3 (UNS N10675 / W.Nr. 2.4600) is a nickel-molybdenum alloy in the same family as Hastelloy B-2 but with substantially improved thermal stability, fabrication characteristics, and resistance to stress-corrosion cracking. It was developed to maintain the excellent hydrochloric acid resistance of B-2 while overcoming that alloy's tendency to form deleterious intermetallic phases (Ni4Mo and Ni3Mo) during exposure in the 650-870°C range. These phases had caused premature failure in welded fabrications and heat-affected zones of B-2 equipment.
The alloy contains approximately 65% nickel and 27-32% molybdenum, with carefully controlled additions of iron, chromium, cobalt, tungsten, and manganese. Unlike Hastelloy C-type alloys, B-3 contains only 1-3% chromium, which means it has very limited resistance to oxidizing media. For this reason, Hastelloy B-3 should be used only in reducing environments or in systems where chlorides, hydrogen chloride, or reducing acids are the primary concern.
Hastelloy B-3 exhibits exceptional resistance to pure hydrochloric acid across the entire concentration range, from dilute solutions to the gaseous hydrogen chloride environment above boiling concentrated acid. It also resists sulfuric acid, phosphoric acid, acetic acid, formic acid, and many non-oxidizing chloride salts. Its performance in hydrochloric acid is generally superior to that of zirconium in certain temperature-concentration regimes and is unmatched among commercially available nickel alloys. When selecting materials for hydrochloric acid service, engineers should verify that no oxidizing species such as ferric or cupric ions are present, as these can dramatically accelerate attack on low-chromium alloys.
The improved thermal stability of Hastelloy B-3 is achieved by reducing the iron content and carefully balancing chromium, cobalt, and tungsten compared with B-2. This composition minimizes the precipitation of ordered Ni-Mo intermetallic phases that embrittle B-2 during intermediate-temperature exposure. As a result, B-3 retains better ductility in the weld heat-affected zone and is less prone to cracking during repair welding or after brief overheating during service. The alloy still requires low heat input welding and rapid cooling through the 650-870°C range, but its process window is significantly wider.
Fabrication of Hastelloy B-3 is similar to other austenitic nickel alloys. Cold forming requires more force than stainless steel due to the high molybdenum content, and the alloy work-hardens rapidly. Annealing between forming operations is typically performed at 1066°C followed by rapid cooling. Welding should use matching ERNiMo-10 filler metal and gas tungsten arc welding with argon backing gas to prevent oxidation. Because of the low chromium content, surface cleanliness is critical; iron contamination from carbon steel tools or fixtures can cause severe galvanic corrosion in service.
At Hangbo Alloy Group, Hastelloy B-3 is supplied as plates, sheets, bars, seamless and welded pipes, fittings, and welding consumables for chemical processing, pharmaceutical manufacturing, and specialty acid-handling equipment. We provide material with full chemical and mechanical certification and can perform non-destructive testing on request.
The chemistry of Hastelloy B-3 is optimized for thermal stability without sacrificing corrosion resistance. Molybdenum is the dominant alloying element and is responsible for resistance to reducing acids. Chromium is intentionally limited because high chromium would form oxides that degrade performance in strongly reducing conditions. Iron and tungsten provide solid-solution strengthening, while carbon and silicon are kept extremely low to minimize carbide and intermetallic phase formation.
| Element | Min % | Max % |
|---|---|---|
| Nickel (Ni) | 65.0 | Balance |
| Molybdenum (Mo) | 27.0 | 32.0 |
| Iron (Fe) | 1.0 | 3.0 |
| Chromium (Cr) | 1.0 | 3.0 |
| Cobalt (Co) | — | 3.0 |
| Tungsten (W) | — | 3.0 |
| Manganese (Mn) | — | 3.0 |
| Silicon (Si) | — | 0.10 |
| Carbon (C) | — | 0.01 |
| Phosphorus (P) | — | 0.03 |
| Sulfur (S) | — | 0.01 |
| Titanium (Ti) | — | 0.20 |
| Copper (Cu) | — | 0.20 |
| Tantalum (Ta) | — | 0.20 |
| Nickel + Molybdenum | 94.0 | — |
Hastelloy B-3 has a face-centered cubic austenitic structure in the annealed condition. Its physical properties are typical of high-molybdenum nickel alloys: relatively high density due to the molybdenum content, low thermal conductivity, and moderate thermal expansion. These properties should be considered during welding and thermal processing to minimize distortion and residual stress.
| Property | Value | Unit |
|---|---|---|
| Density | 9.22 | g/cm3 |
| Melting Range | 1370 - 1418 | °C |
| Specific Heat (21°C) | 377 | J/kg·K |
| Thermal Conductivity (21°C) | 11.1 | W/m·K |
| Electrical Resistivity (21°C) | 1.37 | μΩ·m |
| Modulus of Elasticity (21°C) | 216 | GPa |
| Mean Coefficient of Thermal Expansion (20-100°C) | 10.6 | μm/m·°C |
| Curie Temperature | -196 | °C |
Hastelloy B-3 is normally supplied in the solution-annealed condition. The annealing treatment dissolves any residual secondary phases and restores maximum ductility and corrosion resistance. The mechanical properties listed below are typical for annealed plate and bar per ASTM B333 and ASTM B335.
| Property | Value |
|---|---|
| Tensile Strength | 760 MPa (110 ksi) |
| Yield Strength (0.2% offset) | 350 MPa (51 ksi) |
| Elongation in 2 inches | 40% |
| Reduction of Area | 55% |
| Hardness | 85 - 95 HRB |
| Charpy V-notch Impact (room temp) | 230 J |
Hastelloy B-3 is not a high-temperature alloy. Its useful service range is limited by oxidation resistance and by the need to avoid prolonged exposure in the 650-870°C sensitization range. Equipment should be designed so that operating temperatures remain below 450°C in reducing acid service, and welding repairs should use low heat input to keep the heat-affected zone outside the critical temperature range.
| Temperature (°C) | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| 21 (Room) | 760 | 350 | 40 |
| 100 | 710 | 310 | 42 |
| 200 | 675 | 285 | 43 |
| 300 | 650 | 265 | 44 |
| 400 | 620 | 250 | 45 |
| 500 | 570 | 235 | 46 |
| 600 | 490 | 220 | 48 |
| 700 | 360 | 190 | 52 |
Hastelloy B-3 is the material of choice for severe hydrochloric acid service and offers the best resistance to pure hydrochloric acid of any wrought nickel alloy. It also performs well in other strongly reducing acids and in chloride-bearing environments where oxidizing species are absent or tightly controlled.
Hastelloy B-3 is selected specifically for equipment exposed to reducing acids where other alloys would fail rapidly. Its improved thermal stability has expanded its use to welded fabrications and complex equipment that may experience intermittent elevated temperatures during processing or cleaning cycles.
Hangbo Alloy Group manufactures and stocks Hastelloy B-3 in a wide range of product forms suitable for chemical plant construction and repair. All material is supplied with certified chemical and mechanical test reports and can be inspected to customer-specified NDT levels.
| Standard | Description |
|---|---|
| ASTM B333 | Plate, Sheet, and Strip |
| ASTM B335 | Bar and Rod |
| ASTM B622 | Seamless Pipe and Tube |
| ASTM B619 | Welded Pipe |
| ASTM B626 | Welded Tube |
| ASTM B564 | Forgings |
| ASTM B366 | Fittings |
| AWS A5.14 | Welding Wire (ERNiMo-10) |
| ASME SB-333 | Boiler and Pressure Vessel Code |
Hangbo Alloy Group is a leading supplier of Hastelloy B-3 plates, bars, tubes, pipes, and fittings for severe acid service. We provide technical guidance on material selection, welding procedures, corrosion testing, and export packaging. Our quality system ensures full traceability from melt to final product.
For quotations, material certifications, or technical consultation, contact our sales team or call +86-136-1165-6360. We typically respond within 10 minutes.
Request a quotation for Hastelloy B-3 plates, bars, tubes, or fittings. We stock standard sizes and accept custom orders.