Hangbo Alloy Group
Shanghai · Est. 2012
UNS N07716 — Precipitation-hardenable nickel-chromium-molybdenum alloy with 1100+ MPa yield strength, the corrosion resistance of Inconel 625, and NACE MR0175 sour gas compliance for critical downhole applications.
Custom Age 625 Plus (UNS N07716) is a precipitation-hardenable nickel-chromium-molybdenum alloy engineered to combine the legendary corrosion resistance of Inconel 625 with the high strength of an age-hardenable alloy. By increasing the titanium and aluminum content above standard Inconel 625 levels, the alloy develops a robust gamma double-prime (Ni3Nb) and gamma-prime (Ni3(Ti,Al)) strengthening response during aging, raising yield strength from approximately 520 MPa in the annealed condition to over 1100 MPa (160 ksi) in the fully aged condition — more than double — while preserving the corrosion profile of the parent alloy. This unique combination has made Custom Age 625 Plus the material of choice for critical oil & gas downhole components where neither annealed Inconel 625 nor high-strength corrosion-resistant alloys like MP35N alone are sufficient.
The driving application behind N07716's development was the oil & gas industry's need for a single alloy that could withstand the aggressive combination of sour (H2S-containing) environments, high mechanical loads, and chloride-rich brines found in modern deep and ultra-deep wells. While standard Inconel 625 (UNS N06625) provides excellent corrosion resistance, its annealed yield strength of ~520 MPa is often inadequate for high-pressure completion tools and downhole hardware. Conversely, precipitation-hardened alloys like Inconel 718 or MP35N either lack NACE MR0175 compliance at the required strength level or are significantly more expensive. Custom Age 625 Plus fills this gap, providing ≥1100 MPa yield strength with full NACE MR0175 sour gas compliance at a cost comparable to standard Inconel 625.
The alloy is melted by vacuum induction melting (VIM) followed by vacuum arc remelting (VAR) or electroslag remelting (ESR) to ensure the cleanliness and homogeneity required for sour service. The standard mill product is supplied in the solution-annealed plus aged condition per ASTM B805, with strict hardness control to meet NACE MR0175 limits. At Hangbo Alloy Group, we produce N07716 round bars, wire, plates, forgings, and custom downhole components for oilfield operators and equipment manufacturers worldwide.
Custom Age 625 Plus retains the nickel-chromium-molybdenum-niobium foundation of Inconel 625 with carefully increased titanium and aluminum content to enable age-hardening response. The chromium (20–23%) and molybdenum (8–10%) levels are virtually identical to Inconel 625, preserving its resistance to pitting, crevice corrosion, and a wide range of chemical media. The increased titanium (1.0–1.6%) and aluminum (0.2–0.5%) drive the precipitation of fine gamma-prime and gamma double-prime during aging, with niobium (3.0–4.5%) supporting the dominant gamma double-prime phase. Carbon is kept very low to minimize carbide formation that could deplete strengthening elements and create corrosion initiation sites.
| Element | Min % | Max % |
|---|---|---|
| Nickel (Ni) | 58.0 | 63.0 |
| Chromium (Cr) | 20.0 | 23.0 |
| Molybdenum (Mo) | 8.0 | 10.0 |
| Niobium + Tantalum (Nb+Ta) | 3.0 | 4.5 |
| Titanium (Ti) | 1.0 | 1.6 |
| Aluminum (Al) | 0.20 | 0.50 |
| Iron (Fe) | — | 5.0 |
| Cobalt (Co) | — | 1.0 |
| Carbon (C) | — | 0.03 |
| Manganese (Mn) | — | 0.20 |
| Silicon (Si) | — | 0.20 |
| Phosphorus (P) | — | 0.015 |
| Sulfur (S) | — | 0.010 |
Custom Age 625 Plus has an FCC austenitic matrix in the solution-annealed condition, with strengthening precipitates (gamma double-prime and gamma-prime) forming during aging. The physical properties are nearly identical to Inconel 625 due to the similar base composition, with only minor variations in thermal expansion and electrical resistivity reflecting the increased precipitate volume fraction. The alloy is non-magnetic in both annealed and aged conditions.
| Property | Value | Unit |
|---|---|---|
| Density | 8.40 | g/cm3 |
| Melting Range | 1290 - 1350 | °C |
| Specific Heat (21°C) | 410 | J/kg·K |
| Thermal Conductivity (21°C) | 12.0 | W/m·K |
| Electrical Resistivity (21°C) | 1.30 | μΩ·m |
| Modulus of Elasticity (21°C) | 200 | GPa |
| Mean CTE (21-93°C) | 13.0 | μm/m·°C |
| Magnetic Permeability | <1.005 | Non-magnetic |
The mechanical properties of Custom Age 625 Plus are dramatically different in the annealed versus aged conditions. The annealed condition is supplied primarily as an intermediate form for fabrication and welding, with tensile strength similar to Inconel 625 (~830 MPa). The aged condition, which is the standard mill delivery state, develops yield strength exceeding 1100 MPa while maintaining adequate ductility (15–25% elongation) for structural reliability. Hardness is controlled to ≤40 HRC to maintain NACE MR0175 sour gas compliance. Values below are typical for bar and forgings per ASTM B805 in the aged condition.
| Property | Annealed | Aged (ASTM B805) |
|---|---|---|
| Tensile Strength | 830 MPa (120 ksi) | 1240 MPa (180 ksi) |
| Yield Strength (0.2% offset) | 415 MPa (60 ksi) | 1100 MPa (160 ksi) |
| Elongation in 4D | 45% | 15 - 25% |
| Reduction of Area | 60% | 30 - 45% |
| Hardness | 25 HRC max | 35 - 40 HRC |
| Charpy V-notch Impact | >150 J | 40 - 80 J |
Custom Age 625 Plus requires a carefully controlled two-step heat treatment to achieve optimum strength and corrosion resistance. The aging step precipitates the strengthening phases, while avoiding over-aging that would degrade properties:
Over-aging above 800°C causes the gamma double-prime to transform to the equilibrium delta phase, resulting in irreversible strength loss. Aging below 700°C is impractical due to the extremely long times required to develop peak strength. Hangbo Alloy Group provides full heat treatment certification with each shipment, including recorded time-temperature profiles, hardness survey results, and mechanical test reports.
In the aged condition, Custom Age 625 Plus retains significant strength at elevated temperatures up to approximately 540°C. Above 600°C, the strengthening precipitates begin to overage, with strength loss accelerating. The alloy is not designed for ultra-high-temperature service (unlike nickel superalloys such as Inconel 718 or Waspaloy), but its temperature capability is more than adequate for downhole oil & gas applications where the maximum service temperature is typically limited to 200–230°C by environmental constraints (NACE MR0175) rather than metallurgical limits.
| Temperature (°C) | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| 21 (Room) | 1240 | 1100 | 20 |
| 93 | 1200 | 1060 | 20 |
| 204 | 1130 | 1000 | 21 |
| 316 | 1100 | 970 | 22 |
| 427 | 1060 | 930 | 22 |
| 538 | 1000 | 880 | 23 |
| 649 | 900 | 790 | 25 |
| 760 | 720 | 620 | 30 |
Custom Age 625 Plus retains the excellent corrosion resistance of Inconel 625 in nearly all media. The chromium content (20–23%) provides a passive oxide film that resists oxidizing acids and pitting, while the high molybdenum content (8–10%) provides exceptional resistance to reducing acids, chloride pitting, and crevice corrosion. The aging treatment has minimal effect on corrosion resistance when properly performed, as the strengthening precipitates are uniformly distributed and do not create galvanic cells with the matrix.
Custom Age 625 Plus is the material of choice for the most demanding high-strength, corrosion-resistant applications in oil & gas, subsea, marine, and chemical processing industries. Its unique combination of properties makes it the preferred alloy in the following applications:
Hangbo Alloy Group manufactures and supplies Custom Age 625 Plus (UNS N07716) in a comprehensive range of mill forms, all supported by material test reports, NACE MR0175 hardness certification, and full traceability documentation:
| Standard | Description |
|---|---|
| ASTM B805 | Precipitation-Hardenable Nickel Alloy Bar and Wire |
| ASTM B872 | Precipitation-Hardenable Nickel Alloy Forgings |
| AMS 5833 | Bar, Wire, and Forging Stock, Solution and Precipitation Heat Treated |
| ASME SB-805 | Boiler and Pressure Vessel Code |
| NACE MR0175 / ISO 15156 | Sour Gas Service (Hardness ≤40 HRC) |
| NACE MR0103 | Sour Service in Refining (Hardness ≤40 HRC) |
| API 6A | Wellhead and Christmas Tree Equipment |
| API 17D | Subsea Production Systems |
Custom Age 625 Plus (UNS N07716) has a density of 8.40 g/cm³ (0.304 lb/in³) at room temperature, virtually identical to standard Inconel 625 (8.44 g/cm³). The slight difference reflects the alloy's modified niobium, titanium, and aluminum content designed to enhance age-hardening response.
The melting range of Custom Age 625 Plus is approximately 1290–1350°C (2350–2460°F), comparable to standard Inconel 625. The alloy retains Inconel 625's high melting point, suitable for high-temperature service and welding.
Custom Age 625 Plus (UNS N07716) nominal composition: Ni 58.0–63.0%, Cr 20.0–23.0%, Mo 8.0–10.0%, Nb 3.0–4.5%, Ti 1.0–1.6%, Al 0.20–0.50%, Fe ≤5.0%, C ≤0.03%, Mn ≤0.20%, Si ≤0.20%, P ≤0.015%, S ≤0.010%, Co ≤1.0%. Compared to Inconel 625, the key difference is higher Ti+Al for age hardening.
Key standards for Custom Age 625 Plus include ASTM B805 (precipitation-hardenable nickel alloy bar and wire), ASTM B872 (forgings), AMS 5833 (bar, wire, and forging stock, solution and precipitation heat treated), ASME SB-805 for pressure vessel applications, and NACE MR0175 / ISO 15156 for sour service. The alloy is also widely specified by oil & gas operators under proprietary designations.
The standard heat treatment is: solution anneal at 1093–1204°C (typically 1150°C) for 1–2 hours, water quench or rapid air cool; then age at 700–760°C for 6–10 hours, air cool. The aging step precipitates gamma double-prime (Ni₃Nb) and gamma-prime (Ni₃(Ti,Al)) strengthening phases, increasing yield strength by approximately 60–80% over the annealed condition. Over-aging above 800°C causes strength loss.
Custom Age 625 Plus (UNS N07716) is an age-hardenable variant of Inconel 625 (UNS N06625) with the same corrosion resistance but nearly double the yield strength. Key differences: N07716 has higher Ti (1.0–1.6% vs ≤0.4% in N06625) and Al (0.2–0.5% vs ≤0.4% in N06625) for age hardening; N07716 is supplied in aged condition to develop ~1100 MPa yield strength vs ~520 MPa for annealed N06625. Both have similar corrosion resistance to a wide range of media. N07716 is preferred when higher strength and NACE MR0175 sour gas compliance are required at the same time.
Custom Age 625 Plus is priced similarly to Inconel 625 in the annealed condition, with a 10–15% premium for the aged condition due to additional heat treatment. Rough price range: $30–50/kg for round bar in standard sizes, depending on form, size, and specification. Forging stock and large-diameter bar are at the higher end. Contact Hangbo Alloy Group for current pricing and NACE MR0175 certification costs.
Custom Age 625 Plus is available as round bars (10–300 mm dia), wire (0.5–10 mm), plates and sheets (0.5–50 mm), forgings (custom open-die and ring-rolled), and welding wire (ERNiCrMo-3 modified for matching strength). All forms are supplied in the aged condition per ASTM B805 and AMS 5833. Hangbo Alloy Group supplies N07716 with full material test reports, hardness certification per NACE MR0175, and optional ultrasonic testing.
Custom Age 625 Plus has limited weldability in the aged condition. It is best welded in the annealed condition using GTAW with matching filler metal ERNiCrMo-3 (Inconel 625 filler) or slightly over-matched filler, then post-weld aged. The high niobium, titanium, and aluminum content can cause strain-age cracking in the HAZ if welded in the aged condition. For most downhole applications, the alloy is machined from bar rather than welded. When welding is required, electron beam and laser welding are preferred to minimize HAZ width.
Custom Age 625 Plus is designed for service temperatures up to approximately 540°C (1000°F) in the aged condition for long-term applications. Above 600°C, the gamma double-prime and gamma-prime precipitates begin to overage and transform to the equilibrium delta phase, causing strength loss. For sour gas service per NACE MR0175, the alloy is typically limited to 232°C (450°F) due to environmental restrictions, far below its metallurgical limit.
Custom Age 625 Plus is the alloy of choice when both high strength and excellent corrosion resistance are required: (1) Oil & gas downhole — side-pocket mandrels, gas-lift valves, flow control devices, completion tools, and packer components in sour (H₂S-containing) wells. (2) Subsea — tieback connectors, manifolds, and high-strength fasteners for subsea production systems. (3) Marine — high-strength fasteners, pump shafts, and valve stems for seawater service. (4) Chemical processing — high-pressure reactor bolts, agitator shafts, and pump casings. (5) Aerospace — structural fasteners and high-strength corrosion-resistant components.
Yes, Custom Age 625 Plus is one of the most widely used nickel alloys for NACE MR0175 / ISO 15156 sour gas service. The alloy is approved for use in all SSC (sulfide stress cracking) regions when hardness is controlled to ≤40 HRC (typically 35–38 HRC in the aged condition). It is approved for use with H₂S partial pressures up to the highest severity levels in the standard, making it the preferred material for critical downhole components in sour wells. Many operators have approved it for use in environments where Inconel 625 (annealed) is inadequate due to strength requirements.
Hangbo Alloy Group supplies Custom Age 625 Plus (UNS N07716) in bar, wire, plate, forging, and welding wire forms in both solution-annealed and solution-annealed + aged conditions per ASTM B805, ASTM B872, and AMS 5833. We provide full NACE MR0175 / ISO 15156 hardness certification, optional ultrasonic testing, and metallurgical support for oil & gas, subsea, and chemical processing applications.
For quotations, material certifications, or technical consultation, contact our sales team or call +86-136-1165-6360. We typically respond within 10 minutes.
Request a quotation for N07716 round bars, forgings, plates, or welding wire in solution-annealed or aged conditions. We supply ASTM B805, AMS 5833, and NACE MR0175 compliant material with full certification.