Hastelloy B2 Alloy | N10665 | 2.4617 | Ni-Mo Corrosion Alloy | Fushun Metal

Hastelloy B2 / N10665 / 2.4617 — Introduction

Hastelloy B2, designated UNS N10665 and Werkstoff Nr. 2.4617, is a solid-solution-strengthened nickel-molybdenum wrought alloy engineered specifically for superior resistance to reducing environments. With a nominal 28% molybdenum content and tightly restricted iron and chromium levels, it delivers near-immunity to hydrochloric acid at all concentrations and temperatures, along with outstanding resistance to sulfuric, phosphoric, acetic, and formic acids under non-oxidizing conditions. Unlike precipitation-hardenable grades, Hastelloy B2 derives its corrosion performance and mechanical properties entirely from solid-solution strengthening, making it weldable and fabricable without the risk of strain-age cracking or heat-affected-zone sensitization—provided carbon and silicon are held at the low levels mandated by the specification.

At Fushun Metal, Hastelloy B2 is manufactured through a fully integrated triple-melt route under one roof. VIM primary melting under high vacuum ensures precise control of the ultra-low carbon (≤0.01%) and silicon (≤0.08%) levels that are critical to suppressing beta-phase (Ni₄Mo) precipitation in weld heat-affected zones. The VIM electrode undergoes VAR, where controlled solidification eliminates macro-segregation and produces the chemically homogeneous, low-inclusion microstructure essential for uniform corrosion resistance across large-section components. For the most demanding chemical plant applications—where sulfide-initiated pitting cannot be tolerated—we deploy PESR as the final stage, achieving deep desulfurization and oxide refinement through reactive slag chemistry under inert gas.

Every heat is processed, forged, rolled, and tested within Fushun Metal’s certified quality management system—ISO 9001 for manufacturing process control and AS9120B for aerospace distribution traceability. From initial charge preparation through to the final mill test certificate, each production lot carries full digital traceability linked to melt heat number, remelt sequence, hot-working reduction ratio, and solution-annealing batch. Intergranular corrosion testing per ASTM G28 Method A, ultrasonic inspection, chemical re-verification by optical emission and LECO combustion analysis, and room-temperature tensile testing are standard on every shipment.

Equivalent Grades of Hastelloy B2 Across International Standards

Hastelloy B2 is codified under multiple national and international specification systems. The table below maps its designations and governing standards across major markets. Fushun Metal certifies to all listed specifications and can dual-certify heats where required.

Applications of Hastelloy B2

Hastelloy B2 is the benchmark material for equipment exposed to hot, concentrated reducing acids. It is specified wherever hydrochloric acid, sulfuric acid (non-oxidizing concentrations), phosphoric acid, or aggressive organic acids must be handled at elevated temperatures without risk of pitting, stress corrosion cracking, or general wastage. The alloy is not suitable for oxidizing media—the presence of ferric ions, cupric ions, dissolved oxygen, nitric acid, or chromic acid will cause rapid attack.

Hastelloy B2 — Supply Range by Fushun Metal

Fushun Metal stocks and processes Hastelloy B2 across all major mill forms from a single integrated facility. Our in-house 6000-ton hydraulic open-die press, 1800-ton precision radial forger (GFM), and multi-stand 850/550/350/250 rolling mills enable a broad dimensional envelope without outsourcing—ensuring uninterrupted lot traceability from melt to delivery under ISO 9001 and AS9120B. All material is supplied in the solution-annealed condition per ASTM B335 / B333, fully recrystallized and free of beta-phase embrittlement. Intergranular corrosion testing per ASTM G28 Method A is performed on each heat to confirm freedom from sensitization. Products are accompanied by mill test certificates to EN 10204 3.1 or 3.2 as required.

Chemical Composition of Hastelloy B2 — ASTM B335 / ASTM B333

All heats produced by Fushun Metal are melted via VIM+VAR or VIM+PESR and verified against the composition limits below by optical emission spectrometry and LECO combustion analysis. Full chemical certificates are issued with every shipment under ISO 9001 and AS9120B quality management. The ultra-low carbon and silicon maxima are the critical compositional controls for Hastelloy B2—exceeding these limits promotes beta-phase (Ni₄Mo) precipitation in weld heat-affected zones, which embrittles the grain boundaries and compromises intergranular corrosion resistance in service.

Mechanical Properties of Hastelloy B2 — Per Product Form

Hastelloy B2 is a solid-solution-strengthened alloy; its mechanical properties are developed through controlled hot-working and final solution annealing rather than precipitation hardening. All values below represent minimum guaranteed properties in the solution-annealed condition (typically 1065–1095°C, rapid water quench), per ASTM B335, B333, and B622. Solution annealing dissolves any beta-phase formed during cooling from prior hot-working or welding and restores full ductility and corrosion resistance.

Fushun Metal performs all solution annealing in-house under calibrated furnace controls with rapid water-quench capability. The alloy must not be held or slowly cooled through the 540–815°C temperature range, where beta-phase precipitation kinetics are fastest. For fabricators performing post-weld heat treatment, the same solution-annealing cycle must be applied; stress-relief anneals at intermediate temperatures are explicitly prohibited because they induce embrittlement. Filler metal: ERNiMo-7 (AWS A5.14) for GTAW; electrode: ENiMo-7 (AWS A5.11) for SMAW.

Physical constants: Density 9.22 g/cm³; Melting range 1330–1380°C; Hardness 217–269 HB (≤100 HRB in annealed condition); Modulus of elasticity 217 GPa at 20°C; Thermal conductivity 10.8 W/m·K at 20°C; Coefficient of thermal expansion 11.2 μm/m·°C (20–100°C). The alloy is non-magnetic.