Hastelloy B-2 (N10665)

What is Hastelloy B-2 and its applications?

Hastelloy B-2 (UNS N10665) is a nickel-molybdenum alloy used for reducing-acid chemical service. Selection requires particular attention to oxidizing contaminants and the thermal history of the component.

Reducing-acid processing: Equipment selected against the actual acid concentration and temperature.
Chemical vessels: Wetted components requiring impurity control.
Process piping: Connections with a defined corrosion and mechanical acceptance basis.

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Engineering Application & Selection Guide

High molybdenum and low chromium favor reducing-acid resistance rather than broad resistance to oxidizing media. B-2 can form embrittling Ni₄Mo during certain thermal exposures; its temperature history matters during manufacture and service.

Hastelloy B-2 hex bolts — For acid-pump joints, state oxidizing contaminants and aeration, not only the main acid name.
Hastelloy B-2 stud bolts — For reactor flanges, document heating and cooling operations and any required final anneal.
Hastelloy B-2 hex nuts — For mating nuts, evaluate corrosion compatibility, load capacity and thread engagement as a complete connection.

Compare B-2 and B-3 when fabrication or thermal stability influences the choice. Review the measured fluid chemistry and corrosion data. Do not predict immediate galvanic failure from an alloy mismatch alone.

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Hastelloy B-2 Composition

Selected nominal composition · wt.%

ElementWeight %

Ni: 69 / balance%
Mo: 28%
Cr: ≤1%
Fe: ≤2%
C: ≤0.01%

ASTM / ASME specifications by product form

Finished-product requirements

Specify the finished-fastener mechanical requirements, condition and inspection separately from the starting-stock specification.

Hastelloy B-2 hex bolt requirements ↗

Fasteners · dimensional references

Product	Reference
Hex bolts	ISO 4014 / ISO 4017 · ASME B18.2.1
Threaded studs	DIN 976-1 · ASME B18.31.2
Hex nuts	ISO 4032 · ASME B18.2.2
Socket head screws	ISO 4762 · ASME B18.3
Flat washers	ISO 7089 / ISO 7090 · ASME B18.21.1
Custom fasteners	Customer drawing

Raw-material specifications

Product form / scope	Reference
Rod & bar · Historical reference; specify the required revision.	ASME SB-335

Dimensions do not define material or finished-part compliance. Specify the grade, condition and applicable requirements.

How to specify round bar, plate, wire and strip ↗

Hastelloy B-2 Mechanical Properties

Reference sample and condition

Data basis: Average laboratory reference
Test sample form: Sheet & plate
Sample size: 2.5–8.9 mm thickness
Condition: Solution heat treated
Test temperature: Room temperature
Heat treatment: 1066°C (1950°F), rapid quenched.
Gauge length: 2 in (50.8 mm)

Key properties	Value
Tensile strength	894 MPa
0.2% yield strength	412 MPa
Elongation	61%

Haynes · B-2 (archived bulletin) · H-2006D (1997), pages 3 & 5 · copy hosted by Nickel Systems; archive reference ↗

Procurement and application guide

Specify the material and final condition

Check oxidizing impurities, particularly ferric or cupric salts.

Material forms in the technical reference: Rod & bar · Sheet · Plate.

Define the finished-part acceptance

Include the material or bolting specification, required final condition, dimensions and quantity. State the service medium, temperature and loading where known. Agree the required tests, inspection coverage and acceptance criteria for the finished part.

Start with the information you have

Send a drawing or share the product form and dimensions. Identify any undecided requirements for review rather than copying a typical property value into the purchase order.

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