Project Description
Incoloy 800 (UNS N08800 / W. Nr. 1.4876 / X10CrNiAlTi32-21) is an austenitic nickel-iron-chromium alloy containing 30–35 % Ni, 19–23 % Cr, and a controlled balance of iron, aluminum, and titanium. This composition produces exceptional resistance to oxidation, carburization, and nitriding at temperatures up to 1,100 °C, combined with metallurgical stability that prevents sigma-phase embrittlement during long-term high-temperature service. In oil and gas processing, Incoloy 800 bar is specified for fired furnace internals, steam reformer components, refinery heater tube supports, and heat exchanger parts where austenitic stainless steels suffer excessive scaling or creep. The 800-series alloy family also includes 800H (N08810 — higher carbon for enhanced creep strength) and 800HT (N08811 — higher Al + Ti for maximum elevated-temperature rupture life), allowing engineers to select the optimal grade for each temperature range. SHUNFU METAL supplies all three variants from VIM-cast heats, grain-size controlled per ASTM B408, with EN 10204 3.1 / 3.2 MTR on every shipment.
Incoloy 800 / N08800 — Introduction
The key differentiator of Alloy 800 versus conventional austenitic stainless steels (e.g. 310S) is its high nickel content — at 30–35 % Ni, the alloy is immune to chloride-induced SCC and resists sigma-phase embrittlement that afflicts iron-based heat-resistant grades after prolonged service above 700 °C. The aluminum and titanium additions (0.15–0.60 % each) strengthen the oxide film and maintain dimensional stability during thermal cycling, which is critical for components in fired heaters and steam generators that experience frequent start-stop cycles. Alloy 800 is approved under ASME Boiler and Pressure Vessel Code Section II and listed in NACE MR0175 / ISO 15156 for sour service environments.
SHUNFU METAL hot-forges or hot-rolls N08800 ingots to bar, then applies a solution anneal at 980–1,050 °C (water quench or rapid air cool) to dissolve carbides and produce a homogeneous grain structure. Grain size is verified per ASTM E112 — ASTM No. 5 or finer for standard 800, and grain size 5 or coarser for 800H/800HT grades per the respective ASTM standards. Each lot is 100 % ultrasonically tested per ASTM E114, and intergranular corrosion tests per ASTM A262 Practice E are available on request.
Equivalent Grades & Applicable Standards
| Standard Body | Alloy 800 (N08800) | Alloy 800H (N08810) | Alloy 800HT (N08811) | Specification / Form |
|---|---|---|---|---|
| ASTM / ASME | N08800 | N08810 | N08811 | B408 / SB-408 (bar), B409 (plate), B407 (tube), B564 / SB-564 (forgings) |
| AMS | — | AMS 5766 | AMS 5871 (sheet/plate) | AMS 5766 (bar & forgings — 800H), AMS 5871 (sheet — 800HT) |
| EN / DIN | X10CrNiAlTi32-21 / 1.4876 | X5NiCrAlTi31-20 / 1.4958 | X8NiCrAlTi32-21 / 1.4959 | EN 10028-7 (pressure vessels), EN 10095 (heat-resistant), DIN 17460 (bar), DIN 17459 (tube) |
| BS | NA 15 | — | — | BS 3076 NA15 (bar), BS 3074 NA15 (tube), BS 3072 NA15 (plate) |
| JIS | NCF 800 | NCF 800H | — | JIS G4902 (bar) |
| AFNOR | Z5 NC 35-20 | — | — | NF A-05-054 |
| ISO | NiFe30Cr21AlTi | — | — | ISO 9723 (bar & rod), ISO 4955A |
| NACE / ASME Code | N08800 | N08810 | N08811 | NACE MR0175 / ISO 15156-3; ASME Code Cases N201, N254, 1325; VdTÜV 412 & 434 |
Oil & Gas Applications — Incoloy 800 Bar Components
Outlet pigtail bar stock and header mandrel forgings for SMR furnaces in hydrogen and ammonia plants operating at 800–950 °C.
Tube support bars, hanger rods, and guide clips in crude oil and vacuum distillation fired heaters exposed to flue gases containing sulfur species.
Shell-and-tube exchanger tie rods, spacers, and baffle plates in high-temperature process streams such as pre-heat trains and effluent coolers.
Quench ring mandrels, transfer line exchanger (TLE) components, and dilution steam injector bars in ethylene and olefin cracking furnaces.
Flare tip retaining rods, igniter brackets, and pilot burner support bars withstanding continuous oxidizing flame exposure above 900 °C.
Catalyst support grid bars, thermowell sleeves, and quench distributor spiders in HDT and HDC reactors handling hydrogen at 300–450 °C.
Vessel stud bolting, nozzle flanges, and manway cover bars in NACE MR0175-qualified sour service pressure vessels for H₂S-bearing natural gas processing.
Immersion heater element sheaths, coil support bars, and retention clips in crude oil and produced-water heating tanks on floating production (FPSO) vessels.
Supply Forms & Size Range — Incoloy 800 Bar
| Form | Size Range | Applicable Standard | Condition |
|---|---|---|---|
| Hot-Rolled Round Bar | Ø 6 mm – Ø 250 mm | ASTM B408 | Annealed (hot-finished) |
| Hot-Rolled Flat Bar | Thickness 6–120 mm × Width 20–400 mm | ASTM B408 | Annealed |
| Cold-Drawn Round Bar | Ø 3 mm – Ø 80 mm | ASTM B408 | Annealed or cold-drawn |
| Forged Round Bar | Ø 80 mm – Ø 800 mm | ASTM B564 / EN 10269 | Forged + annealed |
| Forged Flat / Block | Thickness 50–400 mm × Width up to 1,200 mm | ASTM B564 / EN ISO 9723 | Forged + annealed |
Grades 800, 800H, and 800HT available in all forms. Standard lengths: 1,000–6,000 mm; cut-to-length available. SHUNFU METAL stocks annealed round bar in Ø 10–Ø 180 mm for prompt delivery. All surfaces can be supplied black (as-rolled), turned (peeled), or precision-ground to h9/h11 tolerance. Grain size certificates are provided for 800H/800HT lots.
Chemical Composition — ASTM B408 Alloy 800 / 800H / 800HT
| Grade | Ni | Cr | Fe | C | Al | Ti | Al + Ti | Mn | Si | S |
|---|---|---|---|---|---|---|---|---|---|---|
| Alloy 800 N08800 |
30–35 | 19–23 | ≥ 39.5 | ≤ 0.10 | 0.15–0.60 | 0.15–0.60 | 0.30–1.20 | ≤ 1.50 | ≤ 1.00 | ≤ 0.015 |
| Alloy 800H N08810 |
30–35 | 19–23 | ≥ 39.5 | 0.05–0.10 | 0.15–0.60 | 0.15–0.60 | 0.30–1.20 | ≤ 1.50 | ≤ 1.00 | ≤ 0.015 |
| Alloy 800HT N08811 |
30–35 | 19–23 | ≥ 39.5 | 0.06–0.10 | 0.25–0.60 | 0.25–0.60 | 0.85–1.20 | ≤ 1.50 | ≤ 1.00 | ≤ 0.015 |
Bold cells show the key differentiating elements between grades. Alloy 800HT’s higher Al + Ti (≥ 0.85 %) and tighter carbon range provide maximum creep-rupture life above 800 °C. SHUNFU METAL performs ICP-OES on every heat for full 10-element chemistry; Al and Ti are reported individually on every MTR.
Mechanical Properties — Incoloy 800 Bar (Annealed, 20 °C)
| Grade / Condition | Tensile Strength Rm (MPa) |
Yield Strength Rp0.2 (MPa) |
Elongation A₅ (%) |
Hardness HB |
|---|---|---|---|---|
| Alloy 800 — Annealed N08800 / ASTM B408 |
≥ 450 (typ. 520–680) | ≥ 170 (typ. 205–310) | ≥ 30 | ≤ 192 |
| Alloy 800H — Annealed N08810 / ASTM B408, Grain ≥ ASTM No. 5 |
≥ 450 (typ. 490–660) | ≥ 170 (typ. 195–290) | ≥ 30 | ≤ 185 |
| Alloy 800HT — Annealed N08811 / ASTM B408, Grain ≥ ASTM No. 5 |
≥ 450 (typ. 485–650) | ≥ 170 (typ. 190–275) | ≥ 30 | ≤ 185 |
| Cold-Drawn (800 / 800H) No anneal after drawing |
620–860 | 380–550 | ≥ 20 | 180–240 |
Standards: ASTM B408 (bar), EN 10028-7 (pressure vessel plate), DIN 17460 (bar). Density: 8.0 g/cm³. Melting range: 1,357–1,385 °C. Modulus of elasticity: 194 kN/mm². SHUNFU METAL performs full tensile testing and hardness survey on each lot; elevated-temperature tensile data at 400 °C, 600 °C, and 800 °C per ASME BPVC Section II available on request. Creep-rupture data for 800H/800HT is available per ASTM E139 for high-temperature pressure vessel qualification.