Project Description
Incoloy G-3 (UNS N06985 / W. Nr. 2.4619 / NiCr22Mo7Cu) is a nickel-chromium-iron alloy engineered with precisely controlled additions of molybdenum (6.0–8.0 %), copper (1.5–2.5 %), cobalt (≤ 5.0 %), and an ultra-low carbon ceiling of ≤ 0.015 % to deliver broad corrosion resistance under both oxidizing and reducing conditions. The combination of high Ni and Cu content imparts outstanding resistance to reducing acids — sulfuric, phosphoric, and hydrochloric — while the high Cr and Mo levels simultaneously provide excellent resistance to pitting, crevice corrosion, and chloride-induced SCC. Classified as a Type 4d alloy under NACE MR0175 / ISO 15156-3, Alloy G-3 bar is extensively deployed as OCTG and as machined downhole components in hot, sour high-pressure / high-temperature (HPHT) wells where partial pressures of H₂S would rapidly degrade conventional stainless steels. SHUNFU METAL supplies N06985 bar from VIM+VAR-refined heats, solution-annealed, 100 % ultrasonically tested, with EN 10204 3.1 / 3.2 MTR on every shipment.
Incoloy G-3 / N06985 — Introduction
Alloy G-3 was developed as an improved version of Alloy G, with tighter control over minor elements — particularly tungsten (≤ 1.5 %), niobium (≤ 0.5 %), and carbon (≤ 0.015 %) — to minimise heat-affected-zone (HAZ) sensitisation during welding and to enhance weldability without post-weld solution annealing. The nickel-matrix base (balance Ni, ≈ 44 %) combined with high chromium (21–23.5 %) and molybdenum (6–8 %) yields a PREN (Pitting Resistance Equivalent Number) typically above 45, placing it well above duplex stainless steels in pitting resistance in seawater and acid brine. When cold-worked to OCTG grades, G-3 achieves tensile strengths up to 896 MPa (130 ksi) while remaining within NACE MR0175 hardness limits, making it uniquely suited to HPHT sour wells where both corrosion resistance and mechanical strength are paramount.
At SHUNFU METAL, G-3 billets are VIM-melted to achieve ultra-low sulphur and phosphorus, then VAR or ESR re-melted for enhanced segregation control. Hot forging at 1,000–1,150 °C followed by solution annealing at 1,100–1,150 °C and rapid water quench ensures a fully austenitic microstructure free of sensitisation. Finished bar is 100 % ultrasonically tested per ASTM E114, with intergranular corrosion (IGC) screening available per ASTM A262 Practice C. Hardness verified at ≤ 35 HRC per NACE MR0175 requirements. Third-party inspection by SGS, Bureau Veritas, or TÜV available on request.
Equivalent Grades & Applicable Standards — N06985
| Standard Body | Designation | Applicable Specification / Form |
|---|---|---|
| ASTM / ASME | UNS N06985 | B581 / SB-581 (billet, rod & bar), B582 / SB-582 (plate / sheet / strip), B619 / SB-619 (welded pipe), B622 / SB-622 (seamless pipe & tube), B626 / SB-626 (welded tube), B366 / SB-366 (fittings), B564 / SB-564 (forgings) |
| EN / DIN | 2.4619 / NiCr22Mo7Cu | DIN 17752 (bar), DIN 17750 (plate / sheet / strip), DIN 17751 (seamless pipe & tube), DIN 17744 (general wrought), ISO 6208 (plate / sheet) |
| Trade Names | INCONEL® G-3 / HASTELLOY® G-3 / Nicrofer® 4823hMo | All names refer to the same UNS N06985 / 2.4619 composition |
| AWS (Welding) | ERNiCrMo-9 / ENiCrMo-9 | AWS A5.14 (filler metal), AWS A5.11 (welding electrode) |
| GB (China) | NS3303 / NS111 | GB/T 15007 (wrought nickel alloy), YB/T 4323 (centrifugal cast tube blank) |
| NACE / ISO Sour | Type 4d alloy | NACE MR0175 / ISO 15156-3; no H₂S partial pressure restriction below 300 °F (150 °C); approved up to 300 psi H₂S at 425 °F (218 °C) |
Oil & Gas Applications — N06985 Bar Components
- OCTG casing & tubing couplings
- Downhole packer mandrels
- Subsurface safety valve (SSSV) bodies
- Perforating gun frames & carriers
- Lock mandrels & nipple profiles
- Wireline & slickline tool bars
- Wellhead spool body bars
- Gate valve stems & seats
- Choke body & bean holders
- Hanger profiles (tubing / casing)
- Christmas tree component bars
- High-pressure flange bolting
- H₂S scrubber internals & shafts
- FGD quencher tower fittings
- Amine absorber trays & downcomers
- HDS reactor thermowell bars
- Sour condensate separator internals
- Acid gas injection (AGI) pump shafts
- Phosphoric acid evaporator internals
- Sulfuric acid pump shafts & impellers
- Chemical injection valve bodies
- Saltwater injection well mandrels
Supply Forms & Dimensions — Incoloy G-3 Bar
| Form | Standard | Size Range | Condition |
|---|---|---|---|
| Hot-rolled Round Bar | ASTM B581 / DIN 17752 | Ø 6 – Ø 250 mm | Solution annealed |
| Cold-drawn Round Bar | ASTM B581 / DIN 17752 | Ø 6 – Ø 100 mm | Annealed or OCTG cold-worked |
| Hot-rolled Flat Bar | ASTM B582 / DIN 17750 | T: 6–150 mm × W: 20–500 mm | Solution annealed |
| Forged Round Bar | ASTM B564 / DIN 17752 | Ø 50 – Ø 700 mm | Forged + solution annealed |
| Forged Flat Bar / Billet | ASTM B564 / DIN 17752 | T: 30–400 mm × W: 50–800 mm | Forged + solution annealed |
Standard length: 1,000–6,000 mm; custom lengths to 8,000 mm available. Centreless-ground finish (h9/h11 tolerance) available for hot-rolled rounds ≤ Ø 200 mm. OCTG cold-worked bars certified per NACE MR0175 / ISO 15156-3 hardness limits.
Chemical Composition — Incoloy G-3 per ASTM B581 / B582
| Ni | Cr | Fe | Mo | Cu | Co | W | Nb+Ta | C | Mn | Si | S | P |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bal. | 21.0–23.5 | 18.0–21.0 | 6.0–8.0 | 1.5–2.5 | ≤ 5.0 | ≤ 1.5 | ≤ 0.50 | ≤ 0.015 | ≤ 1.0 | ≤ 1.0 | ≤ 0.030 | ≤ 0.040 |
| All values in weight %. Ni = balance (nominally ≈ 44 %). Ultra-low C (≤ 0.015 %) minimises sensitisation; controlled Nb+Ta limits HAZ carbide precipitation. | ||||||||||||
Mechanical Properties — N06985 Bar
| Condition | Tensile Strength Rm (MPa / ksi) |
0.2% Yield Strength Rp0.2 (MPa / ksi) |
Elongation A₅ (%) |
Hardness (HRC / HBW) |
|---|---|---|---|---|
| Annealed Sheet & Plate 1,100–1,150 °C, water quench |
≥ 621 / ≥ 90 | ≥ 241 / ≥ 35 | ≥ 45 | ≤ 25 HRC / ≤ 255 HBW |
| OCTG Cold-Worked Bar Cold-work + final anneal, NACE MR0175 |
≥ 896 / ≥ 130 | ≥ 586 / ≥ 85 | ≥ 13 | ≤ 35 HRC / ≤ 321 HBW |
| Hot-Finished Bar (Forged) Solution annealed, air or water cool |
≥ 650 / ≥ 94 | ≥ 255 / ≥ 37 | ≥ 40 | 140–220 HBW |
| At 204 °C (400 °F) — Annealed Elevated temperature properties |
≥ 580 / ≥ 84 | ≥ 220 / ≥ 32 | ≥ 45 | — |
Physical constants at 20 °C: density 8.3 g/cm³; modulus of elasticity 211 kN/mm²; thermal conductivity 11.1 W/m·K; electrical resistivity 1.15 Ω·mm²/m. NACE MR0175 OCTG cold-worked condition restricts hardness to ≤ 35 HRC (≤ 321 HBW) for sour-service compliance.