Material Family

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

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

Common Designations

UNS N09925, Incoloy 925, W.Nr. 1.4532 (similar)

The premier high-strength, corrosion-resistant alloy for sour service. "Incoloy" is a trademark of Special Metals Corporation.

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
C: ≤ 0.03
Mn: ≤ 0.50
Si: ≤ 0.50

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

Mechanical Properties (Solution Annealed & Aged Plate - Typical)

Tensile Strength (Rm): 965 - 1170 MPa
Yield Strength (Rp0.2): 690 - 860 MPa
Elongation (A): 15 - 25%
Hardness: 28 - 38 HRC

Strength is more than double that of annealed 825, meeting the requirements for high-grade OCTG (Oil Country Tubular Goods) and fasteners.

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 corrosion-resistant alloys lack sufficient strength.

Heat Treatment Condition

Supplied in Solution Annealed condition for fabrication. Final properties are achieved by a two-step aging treatment (e.g., 720°C/8hrs, furnace cool to 620°C, hold 8hrs, air cool).

Critical: Like Alloy 718, the final aging is typically performed post-fabrication to develop full strength.

Key Standards (Plate)

ASTM B805 (Standard Specification for Precipitation Hardening Nickel Alloy Plate, Sheet, and Strip), API 6A CRA (for wellhead), NACE MR0175

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

Form Availability

Plate, Bar, Forging Stock, Tubular Products (OCTG), Fasteners

Primarily used for machined components like wellhead parts, valve bodies, hangers, and downhole tools.

Typical Applications

• Oil & Gas: Downhole Tubing & Casing, Wellhead Components (trees, hangers), Valve Bodies, Subsea Equipment in sour fields.
• Fasteners (bolts, studs) for corrosive, high-strength applications.
• High-Strength Shafts and Pumps in Chemical Processing.

The dominant material for critical, high-strength components in sour (H₂S) service where both strength and environmental cracking resistance are mandatory.