Material Family

Nickel-Copper-Aluminum-Titanium Alloy (Precipitation-Hardenable)

A high-strength version of the Monel family, gaining properties via heat treatment.

Common Supply Conditions

1. Solution Annealed (Soft Condition): For all forming, machining, and welding. 

2. Solution Treated & Aged (STA): Supplied in the final high-strength condition for direct assembly.

Most pipe for fabrication is supplied Solution Annealed; final aging is done post-fabrication.

Chemical Composition (Typical wt.%)

Ni: ≥ 63.0 (Balance)
Cu: 27.0 - 33.0
Al: 2.30 - 3.15
Ti: 0.35 - 0.85
Fe: 2.0 max
Mn: 1.5 max
C: ≤ 0.25

The additions of Aluminum (Al) and Titanium (Ti) enable age-hardening by forming the γ' (Ni₃(Al,Ti)) strengthening precipitates.

Mechanical Properties (Typical)

Solution Annealed (As-Supplied):
• Tensile: 620 - 790 MPa
• Yield: 210 - 480 MPa
• Elongation: 35 - 45%
After Full Aging (Aged):
• Tensile: 965 - 1200 MPa
• Yield: 690 - 965 MPa
• Elongation: 20 - 30%

The dramatic strength increase after aging is the core value. Achieves strength similar to alloy steel while being corrosion-resistant.

Physical Properties

Density: 8.44 g/cm³
Melting Range: 1315 - 1350 °C
Useful Service Range: Cryogenic to about 480°C (900°F), beyond which overaging occurs.

Maintains its enhanced strength in typical marine and downhole environments.

Key Performance Attributes

• High Strength-to-Weight Ratio, Excellent Fatigue Strength, and Low Magnetic Permeability.

• Excellent resistance to seawater and marine atmospheres (similar to Monel 400). Resists chloride stress corrosion cracking.
• Good resistance to hydrofluoric acid, alkalis, and many organic acids.

• Poor resistance to oxidizing acids (e.g., nitric acid).

Combines marine-grade corrosion resistance with the strength of steel.

Key Standards (Pipe)

Seamless Pipe: ASTM B865 / ASME SB-865 (for Solution Heat Treated material), ASTM B564 (Forged or Rolled Fittings) can also apply.
NACE MR0175/ISO 15156 compliance for sour service.

ASTM B865 is the primary specification for solution-annealed pipe and tube.

Heat Treatment (Aging)

Standard aging: 595°C (1100°F) for 16-20 hours, air cool. Sometimes a two-step age is used. For Solution Annealed pipe, this is performed after all fabrication/welding is complete.

This aging treatment is essential to develop the high strength and hardness.

Common Sizes & Forms

OD Range: Typically from small tubing (~1/4") to larger pipe for shafts and sleeves (up to 8" NPS).
Wall Thickness: Varies widely; heavy walls are common for machined shafting.
Forms: Primarily Seamless (SMLS).

Often used as hollow bar stock for machining into components rather than as long process piping runs.

Typical Applications

• Marine Engineering: Propeller shafts, pump rods, fasteners (bolts, studs), valve stems for seawater systems, boat shafting.
• Oil & Gas: Non-magnetic drill collars, wellhead components, springs, and instruments for sour service.
• Aerospace & Defense: High-strength fasteners, precision springs.
• Chemical Processing: High-strength shafts, impellers, and wear sleeves for corrosive services.

The go-to material for critical, high-strength rotating components and fasteners in seawater and sour service environments.