Material Family

Nickel-Molybdenum Alloy (Thermally Stable, Low Iron, Low Carbon) Coil/Strip

The coiled form of the modern successor to B-2, with optimized chemistry for stability.

Common Forms & Tempers

Forms: Cold Rolled Coil (Strip), Annealed Pickled Coil.
Temper: Typically supplied in Annealed (Soft) temper for optimal formability and corrosion resistance.

The annealed condition is standard, offering the best combination of properties for stamping and forming.

Chemical Composition (Typical wt.%)

Ni: ≥ 65.0 (Balance)
Mo: 27.0 - 32.0
Cr: 1.0 - 3.0
Fe: 1.0 - 3.0
Al: ≤ 0.50
Ti: ≤ 0.20
C: ≤ 0.010
Si: ≤ 0.10

High Mo for reducing acid resistance. Controlled, low levels of Cr & Fe and additions of Al/Ti dramatically improve thermal stability over B-2.

Mechanical Properties (Annealed Coil, Room Temp)

Tensile Strength (Rm): 827 - 1034 MPa
Yield Strength (Rp0.2): 414 - 690 MPa
Elongation (A): 40 - 55%

Exhibits higher typical strength than B-2 while maintaining excellent ductility for forming.

Coil Physical Specifications (Typical)

Thickness: 0.20mm - 2.5mm (0.008" - 0.100")
Width: 10mm - 600mm (0.4" - 24")
Coil I.D.: 300mm, 405mm, 508mm (12", 16", 20")
Coil Weight: 50kg - 1000kg

Supplied with precise dimensional tolerances suitable for progressive die stamping.

Key Corrosion Resistance

• Equal or superior resistance to B-2 in pure hydrochloric acid (HCl) across all concentrations and temperatures.• Excellent resistance to sulfuric (H₂SO₄), phosphoric (H₃PO₄), and acetic acids under strictly reducing conditions.• ⚠️ Same Major Limitation: Poor resistance to oxidizing agents (e.g., Fe³⁺, Cu²⁺ ions, HNO₃, oxygen). Oxidant contamination must be avoided.

Matches B-2's legendary reducing acid performance. The primary difference is not corrosion, but fabricability.

Primary Advancement: Thermal Stability

Dramatically improved resistance to embrittlement caused by precipitation of intermetallic phases when held in or slowly cooled through the 550-1050°C range. This makes it far less sensitive during welding and heat treatment than B-2.

This is the single most important reason to choose B-3 over B-2 for new designs. It enables safer, more reliable fabrication.

Key Standards (Strip/Coil)

ASTM B333 / ASME SB-333 (Grade UNS N10675), DIN 2.4600

Procured under the same ASTM standard as B-2 coil, but to the N10675 composition.

Fabrication Note

Significantly easier and safer to weld and fabricate than B-2. While controlled procedures are still recommended, the risk of forming brittle phases in the heat-affected zone (HAZ) is greatly reduced. Post-weld heat treatment is less frequently required.

Enables the production of more complex stamped-and-welded assemblies for reducing acid plants.

Typical Coil Applications

• HCl & Reducing Acid Systems: Gaskets, bellows, pump diaphragms, valve trim, heat exchanger plates for high-temperature service.
• Chemical Processing: Components for acetic anhydride, alkylation, and other oxygen-free processes.
• Parts requiring welding or complex forming in reducing acid service, where B-2 would be risky.

Used for high-volume parts in the same severe reducing processes as B-2, but where fabricability, weld integrity, and long-term thermal stability are critical.