Material Family

Nickel-Iron-Chromium-Molybdenum-Copper Precipitation-Hardenable Superalloy

A high-strength variant of the 825 family, designed for age-hardening.

Common Forms (Bar)

Hot Rolled, Forged, or Cold Finished Rounds, Hexagons. Also supplied as Forging Billet or Upset Bar for downhole tool forgings.

Often supplied as round bar for machining high-strength parts or as forging stock.

Common Supply Conditions

1. Solution Annealed (Soft Condition): For all machining, threading, and cold working.

 2. Solution Treated & Aged (STA): Directly supplied in the final high-strength condition.

Most bar for fabrication is supplied Solution Annealed; final aging is done post-machining. STA bar is for parts requiring no further heat treatment.

Chemical Composition (Typical wt.%)

Ni: 42.0 - 46.0
Cr: 19.5 - 22.5
Fe: ≥ 22.0 (Balance)
Mo: 2.5 - 3.5
Cu: 1.5 - 3.0
Ti: 1.9 - 2.4
Al: 0.1 - 0.5

Composition builds on alloy 825, with critical additions of Titanium (Ti) and Aluminum (Al) to form the γ' (Ni₃(Al,Ti)) strengthening precipitates during aging.

Mechanical Properties (Typical)

Solution Annealed (As-Supplied):
• Tensile: 690 - 860 MPa
• Yield: 345 - 550 MPa
• Elongation: 25 - 40%
After Full Aging (Aged - ASTM B805):
• Tensile: 965 - 1170 MPa
• Yield: 690 - 860 MPa
• Elongation: 15 - 25%

The dramatic strength increase after aging is the core value, meeting requirements for high-grade OCTG and downhole tools.

Physical Properties

Density: 8.08 g/cm³
Melting Range: 1345 - 1385 °C
Primary Service Range: Up to ~205°C (400°F) for sour service; higher for non-sour applications.

Strength is maintained in the typical downhole temperature range.

Key Performance Attributes

• High Strength & Excellent Sulfide Stress Cracking (SSC) Resistance per NACE MR0175/ISO 15156.
• Excellent chloride stress corrosion cracking (Cl-SCC) and pitting resistance.

• Good resistance to sour (H₂S/CO₂/Cl⁻) and slightly oxidizing environments.

• Good general corrosion resistance similar to alloy 825.

Engineered specifically for high-stress components in sour oil & gas production where standard CRAs lack sufficient strength.

Key Standards (Bar)

ASTM B805 (Precipitation Hardening Nickel Alloy Bars, Forgings, and Forging Stock), NACE MR0175/ISO 15156 (Mandatory for sour service).

ASTM B805 is the primary specification. Compliance with NACE MR0175 is essential for sour service.

Heat Treatment (Aging)

Standard aging: 720°C for 8hrs, furnace cool at 55°C/hr to 620°C, hold 8hrs, air cool. For Solution Annealed bar, this is performed after all machining/threading is complete.

This two-step aging is essential to develop the full γ' precipitate strengthening and achieve NACE compliance for sour service.

Machinability

Machinability (Annealed): ~35%. Machinable with techniques for nickel alloys. Tough and work-hardening.
Machinability (Aged): Extremely difficult; should be avoided. All heavy machining must be done in the soft, solution-annealed condition.

The "machine soft, then age harden" sequence is critical.

Typical Bar Applications

• Oil & Gas: Sour service tool joints, subs, hangers, valve stems, mandrels, packer parts, high-strength fasteners (bolts, studs).
• General: High-strength shafts, springs, and machined parts for corrosive service requiring high yield strength.

The premier bar material for high-strength, corrosion-resistant components for the sour gas and oil industry.