Discover the latest trends and innovations in the nickel alloy industry. We provide expert insights and in-depth analysis on the newest developments in nickel alloys.
Incoloy 925 (UNS N09925) is an age-hardenable (precipitation hardening) Ni–Fe–Cr–Mo–Cu alloy based on the Incoloy 825 composition, with increased Ti (1.8–2.4 %) and added Al (0.10–0.50 %) to form γ′ precipitates—Ni₃(Ti,Al)—during aging at 620–720 C. Its defining mechanical feature is a minimum yield strength of 758 MPa (110 ksi) in the aged condition, combined with NACE MR0175 / ISO 15156 SSC resistance, which makes it the standard choice for sour-oilfield downhole load-bearing components (packer mandrels, safety-valve stems, hanger parts).
It is not a solid-solution alloy like Incoloy 825—omitting the aging treatment leaves it soft (~380 MPa YS). The data below are for the solution-annealed + aged (precipitation hardened) condition per ASTM B805 / ASME SB805, which is the design-intent state.
Room-Temperature Tensile & Yield Strength (Aged Condition)
Values shown are ASTM B805 minima and typical mill ranges for 110 ksi yield class material.
|
Property |
ASTM B805 Minimum |
Typical Mill Range |
Test Standard |
|---|---|---|---|
|
Tensile Strength, Rm |
≥ 965 MPa (140 ksi) |
1000 – 1170 MPa |
ASTM E8 |
|
Yield Strength, Rp0.2 (0.2 % offset) |
≥ 758 MPa (110 ksi) |
790 – 930 MPa |
ASTM E8 |
|
Elongation, A₅₀ |
≥ 12 % |
15 – 20 % |
ASTM E8 |
|
Reduction of Area, Z |
≥ 45 % |
50 – 60 % |
ASTM E8 |
Common grade supplied: 110 ksi yield (≥758 MPa); 120 ksi yield (≥827 MPa) can be produced by selected mills with tighter process control.
These values are obtained after aging at 650–680 C for 8–16 h, following solution anneal at 910–930 C + water quench.
Material supplied in solution-annealed-onlycondition will show roughly:
Rm ≈ 690–830 MPa / Rp0.2 ≈ 380–480 MPa / A₅₀ ≥ 30 % — suitable for machining prior to customer aging.
Hardness, Toughness & Shear-Related Data (Aged Condition)
|
Property |
Typical / Specified Value |
Note |
|---|---|---|
|
Brinell Hardness (HBW) |
285 – 360 HB |
Corresponds to aged condition |
|
Rockwell Hardness (HRC) |
28 – 38 HRC (typical 30–34 HRC) |
Often used as incoming inspection check |
|
Charpy V-Notch Impact @ −46 C (−50 F) |
≥ 34 J (25 ft‑lbf); typical 40–60 J |
Meets NACE MR0175 low-temp toughness requirement |
|
Shear Modulus, G (RT) |
~76 GPa |
— |
|
Poisson's Ratio, ν (RT) |
0.30 – 0.31 |
— |
Hardness is frequently specified on the purchase order as a receipt-inspection check (e.g., "30–35 HRC after aging"). Excessively high hardness (> 38–40 HRC) may indicate over-aging or improper quench and cancorrelate with reduced SSC margin in sour service—verify compliance with project NACE doc.
Elastic Modulus & Physical Constants (Affects Stress Calculations)
|
Physical Property |
Value |
Remarks |
|---|---|---|
|
Young's Modulus, E (20 C) |
195 – 200 GPa (typical 197 GPa) |
Slightly decreases with temperature |
|
Density, ρ |
8.14 g/cm³ (use 8.15 kg/dm³ for weight calc.) |
— |
|
Melting Range |
1345 – 1400 C |
— |
|
Coefficient of Thermal Expansion, α (20–300 C mean) |
~14.5 × 10⁻⁶ /K |
Close to 300-series SS |
|
Thermal Conductivity (100 C) |
~11.5 W/(m·K) |
— |
|
Specific Heat, cp(20 C) |
~460 J/(kg·K) |
— |
|
Electrical Resistivity (20 C) |
~1.10 µΩ·m |
— |
|
Magnetic State |
Non-magnetic (fully austenitic) |
Both ST and aged |
Elevated-Temperature Strength Trend (Informational — Not for Creep Design)
Incoloy 925 is not listed in ASME Section I / VIII creep tables. The γ′ phase overages progressively above ~590–650 C:
Yield @ 300 C: ~240–280 MPa (still above many carbon steels but ↓ vs. RT)
Yield @ 450 C: ~210–250 MPa
Yield @ 590 C+: significant softening as γ′ coarsens toward η-phase (Ni₃Ti)
Max. recommended stressed service: ≤ 425–480 C for load-bearing; > 650 C only as unstressed or lightly loaded component.
For high-temperature pressure design > 650 C, use Incoloy 800HT (N08811) or Inconel 600/625 as appropriate.
Solution-Annealed vs. Aged — Why the Difference Matters on MTC
|
Condition |
Heat Treatment |
Rp0.2 (typ.) |
Hardness |
Intended Use |
|---|---|---|---|---|
|
Solution Treated (ST) |
910–930 C → WQ |
~380–480 MPa |
~90–95 HRB |
Machining / final customer aging |
|
Solution + Aged (STA) |
ST + 650–680 C × 8–16 h AC/FC |
≥ 758 MPa |
28–38 HRC |
Final installed component (packer mandrel, valve stem, etc.) |
MTC for aged product shall state:
Heat numbers & solution anneal temp/time
Aging temp/time (e.g., 668 C × 12 h)
Aged tensile (Rm ≥ 965 / Rp0.2 ≥ 758 MPa)
Charpy V-notch @ −46 C
Hardness range
Shanghai COCESS Special Alloys Co., Ltd. supplies Incoloy 925 (UNS N09925) in round bar, forged rod, and custom forgings — available solution-annealed only (for in-house aging) or solution-annealed + aged to 110 ksi (≥758 MPa YS) with full EN 10204 3.1 MTC including aged tensile, impact, hardness, and HT records. UT (ASTM A388 Class A/B), PMI, and third-party inspection (SGS / TÜV / BV / DNV) available per project specification.
Website: https://en.cocessalloys.com
Email: sales@cocessalloys.com
