Hastelloy B3, Alloy B3
Products Description
Hastelloy B-3 (UNS N10675, DIN 2.4600) is a nickel-molybdenum-based solid-solution-strengthened alloy. In the past, many of our customers would ask, "What exactly is the difference between Alloy B-2 and Alloy B-3?" We would typically explain to them: "Alloy B-2 is excellent in every respect, save for one issue-during welding or hot working, if the temperature control is even slightly off, the brittle Ni4Mo phase will precipitate along the grain boundaries, causing the material to become brittle almost instantly. Alloy B-3, through an adjustment to its chemical composition, has essentially remedied this flaw." Simply put, Alloy B-2 is 'delicate,' whereas Alloy B-3 is 'rugged."
Its typical applications include: hydrochloric acid synthesis and concentration equipment, sulfuric acid condensers, acetic acid reactors, flue gas desulfurization systems, nuclear fuel reprocessing equipment, and geothermal brine pipelines.
Characteristic Comparison Operating Conditions
In addition to the points mentioned above, Alloy B-3 possesses three core characteristics. By comparing these material properties against your specific operating conditions, you can determine whether it is the right choice for your application:
1. Molybdenum Content: 28–32%-The "Ultimate Weapon" for Hydrochloric Acid Environments
Molybdenum accounts for fully one-third of this material's composition. While molybdenum is expensive, it is well worth the cost; whereas ordinary stainless steel would become riddled with holes after just a few days of immersion in hydrochloric acid, Alloy B-3 remains unscathed even after years of exposure.
2. Resistance to Localized Corrosion-Withstands Pitting, Crevice Corrosion, and Chloride Stress Corrosion
Alloy B-3 boasts a Pitting Resistance Equivalent Number (PREN) of ≥35, demonstrating exceptional performance in reducing acid environments containing chloride ions. Furthermore, it exhibits virtually no susceptibility to stress corrosion cracking.
3. Prohibited Applications-Important Caveats to Note
Alloy B-3 is not a universal solution. It is vulnerable to oxidizing media-such as nitric acid, hydrochloric acid contaminated with ferric or cupric ions (as these ions transform HCl into an oxidizing acid), and hypochlorite-based bleaching agents. If your application requires a metallic material for use in such environments, Alloy B-3 would not be a suitable choice.
Chemical Composition
(UNS N10675)
|
Elements |
Content (%) |
|
S |
≤0.010% |
|
C |
≤0.01% |
|
P |
≤0.030% |
|
AI |
≤ 0.50% |
|
Co |
≤3.00% |
|
Ta |
≤0.20% |
|
W |
≤3.0% |
|
Fe |
1.0%~3.0% |
|
Cr |
1.0%~3.0% |
|
Si |
≤0.10% |
|
Mn |
≤ 3.00% |
|
Zr |
≤0.10% |
|
Ti |
≤0.20% |
|
Nb |
≤0.20% |
|
V |
≤0.20% |
|
Cu |
≤0.20% |
|
Mo |
27.0%~32.0% |
|
Ni |
65.0%~71.0% |
Mechanical Composition
(Solution-annealed condition)
|
Condition & Size |
Tensile Strength |
Yield Strength |
Elongation |
Reduction of Area |
Hardness |
|
MPa, min |
MPa, min |
%, min |
%, min |
Rockwell, max |
|
| ASTM B335 Requirements | ≥760 MPa (110 ksi) | ≥350 MPa (51 ksi) | ≥40% |
... |
≤230 |
We have identified a point that is easily overlooked: Alloy B-3 will still precipitate harmful phases during prolonged exposure within the 550–800°C range, albeit over a significantly longer timeframe compared to Alloy B-2. If a workpiece is expected to operate within this temperature range for extended periods, a change of material should still be considered.
Hastelloy B3 Bars Performance
Unmatched Corrosion Resistance
One of the key advantages of Hastelloy B3 bars is their ability to maintain structural integrity even in highly corrosive media. Unlike conventional alloys, they perform exceptionally well in reducing environments, where hydrochloric acid and other aggressive chemicals are present. This makes them ideal for reactors, heat exchangers, and piping systems in chemical plants where corrosion resistance is critical.
Mechanical Strength at Elevated Temperatures
In addition to their superior corrosion resistance, Hastelloy B3 bars retain excellent mechanical properties at high temperatures. Their thermal stability ensures reliable performance in applications involving extreme heat, such as furnace components and high-temperature processing equipment. This combination of strength and corrosion resistance makes them a cost-effective solution for industries requiring durable materials.
Machinability and Weldability
While Hastelloy B3 bars have moderate machinability, they can be effectively processed using conventional techniques with proper cooling and lubrication to prevent work hardening. Their weldability is another major advantage-common welding methods like gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) produce strong, corrosion-resistant joints, ensuring structural integrity in critical applications.
Key Points for Technical Communication Prior to Quotation
Prior to issuing a formal quotation, it is absolutely essential-and indeed necessary-that we clarify the following technical points. These details are critical in ensuring that the correct materials are selected and that the quotation provided is both accurate and up-to-date.
- Standards: We offer Hastelloy B3 bars conforming to ASTM B335 (the core standard for bars) and ASME SB-335 (the standard for pressure vessels). Which standard do you require?
- Dimensions: Diameter and Length (Common sizes range from 10–80 mm; larger sizes require custom production.)
- Condition: Solution Annealed (Standard delivery condition)
- Surface Finish: Black/As-rolled? Turned? Ground?
- Application: What are the specific service conditions for these bars? Will they be used in a hydrochloric acid environment, or in the presence of other reducing acids?
- Melting Process: Is a dual-vacuum melting process (VIM + VAR) required? This is typically a requirement for high-end applications.
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