Nickel alloy · high-temperature forgings
Incoloy 800H / Alloy 800H / UNS N08810 Forging Parts
Incoloy 800H (Alloy 800H, UNS N08810, W.Nr. 1.4958) is a nickel-iron-chromium alloy containing nominally 32 % Ni, 21 % Cr and a minimum of 39.5 % Fe. It shares its base chemistry with Incoloy 800 but differs in two decisive ways: carbon is fixed inside a narrow 0.05–0.10 % band, and the material is annealed hot enough to produce an average grain size of ASTM No. 5 or coarser. Those two controls give the alloy the creep and stress-rupture strength that makes 800H the standard grade above 593 °C (1100 °F), in ethylene cracking furnaces, steam reformers, superheaters and heat-treatment plant.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forging UNS N08810 into seamless rolled rings to 2,500 mm OD, discs and tube sheets to Ø1,800 mm, shafts to 8 m, sleeves, flange blanks, blocks and bars Ø25–500 mm, up to 8,000 kg single-piece weight. Parts are supplied solution annealed at approximately 1150 °C with rapid cooling, grain size verified to ASTM E112, and EN 10204 3.1 certification as standard with 3.2 third-party witness on request. Quotations are returned within 24 hours of receiving a drawing at sales@steelforgepieces.com.
- UNS
- N08810
- Werkstoff
- 1.4958
- Density
- 7.94g/cm³
- Tensile min
- 450MPa (65 ksi)
- Yield min
- 170MPa (25 ksi)
- Elongation
- 30% min
- Carbon
- 0.05–0.10% defining limit
- Grain size
- ASTM 5or coarser
- Anneal
- 1150°C + rapid cool
- ASME limit
- 816°C (1500 °F), Sec. VIII-1
Trademark notice. INCOLOY® is a registered trademark of Special Metals Corporation. Material made by Special Metals and sold under that brand is theirs. Material produced by Jiangyin Jiangnan Metal Co., Ltd. is correctly described as UNS N08810 / W.Nr. 1.4958 / X5NiCrAlTi31-20 (alloy 800H), the same generic chemistry, manufactured independently. We are not affiliated with, sponsored by, or endorsed by Special Metals Corporation. HASTELLOY® is a registered trademark of Haynes International, Inc.; all other trademarks referenced belong to their respective owners. Write UNS N08810 on the purchase order and the material cannot be rejected on brand grounds.
What forged products are available in Incoloy 800H / UNS N08810?
Jiangyin Jiangnan Metal produces UNS N08810 through three routes, chosen by geometry and order volume. Open-die forging on 25 MN and 40 MN hydraulic presses covers shafts, blocks, hollow bars and large discs. Seamless ring rolling on radial-axial mills produces 800H rings from 200 mm to 2,500 mm outside diameter, which is the usual route for reformer and cracking-furnace flanges, header rings and tube-sheet blanks. Upset forging handles short, large-cross-section discs and hubs. Because 800H work-hardens quickly and must finish above 870 °C, we plan the pass schedule and reheats around the part rather than chasing the last few millimetres on a falling heat.
- Seamless rolled rings
- Contoured & T-section rings
- Forged discs
- Tube sheets
- Forged shafts & spindles
- Sleeves, bushes & hollow bars
- Flange blanks (WN / SO / BL / LWN)
- Forged blocks
- Valve bodies & seat rings
- Nozzles & headers
- Furnace fixtures & hearth hardware
- Round / square / flat bars
- Custom near-net forgings
What is Alloy 800H?
Alloy 800H is a solid-solution austenitic nickel-iron-chromium alloy built for one job: staying strong and intact for years at temperatures where austenitic stainless steels creep, scale or carburise. It is a high-temperature structural alloy, not a corrosion alloy in the sense that Hastelloy C-276 or Alloy 825 are.
The nickel content stabilises the austenite and confers resistance to chloride stress-corrosion cracking. The chromium forms the adherent, chromium-rich oxide that resists oxidation, carburisation and sulfidation. The iron balance keeps the price a long way below fully nickel-based alloys such as 617 or 230, which is why 800H remains the default choice for large furnace and pressure hardware where the duty allows it.
Three points about this grade regularly catch buyers out. Each is covered in detail further down the page:
- It is not hardenable by heat treatment. Strength comes from the solid solution, the carbon level and the coarse grain, not from ageing or quench-and-temper.
- Grain size is a specification requirement, not a nicety. A fine-grained forging can meet every chemistry limit and still be correctly rejected as 800H.
- Below about 593 °C there is no reason to pay for it. Alloy 800 or a 300-series stainless does the same job cheaper. 800H earns its price only in the creep range.
Rule of thumb. If the design temperature is above 593 °C and the component is pressure-retaining or load-bearing for years rather than hours, alloy 800H is the right family. Below that temperature it is usually an over-specification.
Equivalent designations for Incoloy 800H
Buyers write this grade a dozen different ways on the same drawing package. Every designation in the table is the same alloy and we can quote against any of them. The generic UNS number is the one to put on the purchase order.
| System | Designation | Note |
|---|---|---|
| UNS | N08810 | The correct wording for a purchase order |
| Werkstoff / DIN | 1.4958 | German material number |
| EN designation | X5NiCrAlTi31-20 | European name for the same chemistry |
| Trade name | Incoloy® 800H | Special Metals Corporation trademark |
| Common shorthand | Alloy 800H · 800H · incoloy 800h | All refer to N08810 |
| Dual certification | 800H/HT · N08810/N08811 | Meets both 800H and 800HT limits |
| British | BS NA15 | Legacy drawings |
| French | AFNOR Z8NC33-21 | Legacy drawings |
| Japanese | JIS NCF 800H | Regional equivalent |
| Forging spec | ASTM B564 / ASME SB-564 | Our main supply route |
| Bar spec | ASTM B408 / ASME SB-408 | Rod and bar |
| Plate spec | ASTM B409 / ASME SB-409 | Plate, sheet, strip, tube-sheet blanks |
| Tube spec | ASTM B407 / B163 | Seamless pipe and tube |
| Reforging stock | ASTM B472 | Billets and bars for reforging |
| Fittings | ASTM B366 | Elbows, tees, reducers |
| Code approval | ASME Code Case 1325 | Higher design stresses for 800H |
Related grades on this site: Incoloy 800 (N08800) · Incoloy 800HT (N08811) · Inconel 617 · Hastelloy X
Chemical composition of UNS N08810
Limits below follow ASTM B564 for nickel alloy forgings, weight percent. Every heat is verified by ladle and product analysis on a daily-calibrated optical emission spectrometer, and the certificate reports the measured values, not the specification range.
| Element | Min | Max | Why it is there |
|---|---|---|---|
| Nickel (Ni) | 30.0 | 35.0 | Stabilises austenite; resists chloride stress-corrosion cracking |
| Chromium (Cr) | 19.0 | 23.0 | Forms the protective oxide for oxidation, carburisation and sulfidation resistance |
| Iron (Fe) | 39.5 | balance | Base element; keeps cost well below nickel-based alloys |
| Carbon (C) | 0.05 | 0.10 | The defining limit. Carbide precipitation is what raises creep strength over alloy 800 |
| Aluminium (Al) | 0.15 | 0.60 | With titanium, stabilises the structure at temperature |
| Titanium (Ti) | 0.15 | 0.60 | Ties up carbon and nitrogen |
| Al + Ti combined | 0.30 | 1.20 | Narrowed to 0.85–1.20 when dual certified to 800HT |
| Manganese (Mn) | none | 1.50 | Deoxidiser; sulfur control |
| Silicon (Si) | none | 1.00 | Deoxidiser; assists oxidation resistance |
| Copper (Cu) | none | 0.75 | Residual limit |
| Sulfur (S) | none | 0.015 | Held low for hot workability |
On this grade carbon is a controlled addition, not a residual. For most alloys a lower carbon result is a better result. For 800H, a heat that analyses at 0.03 % C is out of specification. It is alloy 800, and it will not deliver the creep life the design assumed. This is the most common reason a mill certificate gets rejected on this grade.
Where a project standard imposes tighter limits, such as restricted cobalt for nuclear work or restricted residuals for high-purity process gas, state them on the enquiry and we will melt or source to those limits.
Mechanical properties of alloy 800H forgings
Room-temperature acceptance values
ASTM B564 sets the minimums a UNS N08810 forging must meet. Typical production values sit well above them; both are shown so the margin is visible.
| Property | ASTM B564 minimum | Typical, as forged & annealed |
|---|---|---|
| Tensile strength | 450 MPa (65 ksi) | ≈ 520 MPa (75 ksi) |
| Yield strength, 0.2 % offset | 170 MPa (25 ksi) | ≈ 205 MPa (30 ksi) |
| Elongation in 4D | 30 % | 40–50 % |
| Reduction of area | not specified | 50–65 % |
| Hardness | not specified | 120–180 HB |
| Average grain size | ASTM No. 5 or coarser | ASTM No. 2–5 |
Indicative short-term strength versus temperature
Typical published values for annealed 800H, given for material selection only.
| Temperature | Tensile strength | Yield strength (0.2 %) | What governs here |
|---|---|---|---|
| 20 °C (68 °F) | ≈ 520 MPa | ≈ 205 MPa | Tensile |
| 540 °C (1000 °F) | ≈ 425 MPa | ≈ 160 MPa | Tensile |
| 650 °C (1200 °F) | ≈ 360 MPa | ≈ 150 MPa | Creep begins to govern |
| 760 °C (1400 °F) | ≈ 230 MPa | ≈ 145 MPa | Creep governs |
| 870 °C (1600 °F) | ≈ 140 MPa | ≈ 110 MPa | Creep governs |
Do not use Table 4 as design allowables. For pressure-retaining design take allowable stresses from the current ASME Boiler and Pressure Vessel Code, Section VIII Division 1, Table UNF-23.2, which tabulates values for 800H / 800HT up to 816 °C (1500 °F). Above roughly 593 °C the short-term tensile number carries little weight, because the part fails by creep rather than by yielding.
Physical properties
Typical values for alloy 800H in the solution-annealed condition. Note the expansion coefficient: at roughly 14–19 µm/m·K it is lower than the 300-series stainless steels, which is one of the quieter reasons 800H is chosen for hardware that cycles between ambient and furnace temperature. Less growth means less distortion and less bolt-load loss at the flange.
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.94 g/cm³ | 0.287 lb/in³ |
| Melting range | 1357–1385 °C | 2475–2525 °F |
| Specific heat at 20 °C | 460 J/kg·K | 0.11 Btu/lb·°F |
| Thermal conductivity at 20 °C | 11.5 W/m·K | 80 Btu·in/ft²·h·°F |
| Mean expansion 20–100 °C | 14.4 µm/m·K | 8.0 µin/in·°F |
| Mean expansion 20–500 °C | 16.8 µm/m·K | 9.3 µin/in·°F |
| Mean expansion 20–900 °C | 18.3 µm/m·K | 10.2 µin/in·°F |
| Modulus of elasticity at 20 °C | 196 GPa | 28.5 × 10³ ksi |
| Electrical resistivity at 20 °C | 0.99 µΩ·m | 596 Ω·circ mil/ft |
| Curie temperature | ≈ −115 °C | ≈ −175 °F |
| Magnetic response at 20 °C | Essentially non-magnetic, austenitic FCC, permeability ≈ 1.01. MT inspection is not possible; specify PT. | |
Creep and stress-rupture behaviour
The features that distinguish alloy 800H all trace back to creep. Above roughly half the absolute melting temperature, which for this alloy means from about 590 °C upward, a metal under constant load deforms slowly and permanently and eventually ruptures. The design question is no longer whether the part will yield, but how many hours it will last at a given stress and temperature.
The two mechanisms that decide 800H's life
Grain-boundary sliding and cavitation
At high temperature grain boundaries are weaker than grain interiors. They slide, and voids nucleate on them. Fewer boundaries means fewer places for damage to start. That is why 800H is annealed hot enough to grow the grain to ASTM No. 5 or coarser, and why fine grain is a rejection condition rather than a bonus.
Carbide precipitation
The 0.05–0.10 % carbon precipitates as fine chromium-rich carbides that pin dislocations and grain boundaries. Alloy 800 with 0.03 % carbon simply does not have enough carbon to do this, which is why its allowable stresses fall away above 593 °C while 800H's continue.
Code position
Data generated on controlled-carbon, coarse-grained alloy 800 was presented to ASME and approved as Code Case 1325, giving higher design stresses for Section I and for Section VIII Divisions 1 and 2. Allowable stresses for 800H / 800HT are tabulated in Section VIII Division 1, Table UNF-23.2 up to 816 °C (1500 °F), a higher tabulated ceiling than almost any other alloy in that table. Alloy 800H is also covered for nuclear construction under Section III.
What to ask for. If your component is pressure-retaining and hot, request the creep and stress-rupture data package with your enquiry, and state the design temperature, design pressure and intended design life in hours. We will confirm what test data can be supplied with the heat and whether stress-rupture testing needs to be added to the order.
🌡️ Service screening: is 800H the right alloy?
ExclusivePick the service temperature and the dominant environment. The tool returns a first-pass verdict for UNS N08810 and names the grade we would quote instead when 800H is the wrong choice.
Screening only. Real behaviour depends on gas composition, carbon and sulfur activity, dew point, cycling frequency, section thickness, stress level and design life. Use this to shortlist, then confirm against the ASME allowable-stress tables and published isocorrosion or carburisation data. Jiangyin Jiangnan Metal Co., Ltd. supplies material to specification and does not accept design responsibility for alloy selection.
800 vs 800H vs 800HT, and when to leave the family
These three grades share one base chemistry and are separated only by carbon, the aluminium plus titanium total, and the anneal and grain size that follow. Material meeting both the 800H and 800HT limits is supplied dual certified as 800H/HT, which is common practice and usually the most economical way to buy.
| Property | Alloy 800 | Alloy 800H | Alloy 800HT |
|---|---|---|---|
| UNS | N08800 | N08810 | N08811 |
| Werkstoff | 1.4876 | 1.4958 | 1.4959 |
| EN designation | X10NiCrAlTi32-21 | X5NiCrAlTi31-20 | X8NiCrAlTi32-21 |
| Carbon, % | 0.10 max | 0.05–0.10 | 0.06–0.10 |
| Al + Ti, % | 0.30–1.20 | 0.30–1.20 | 0.85–1.20 |
| Grain size | not specified | ASTM 5 or coarser | ASTM 5 or coarser |
| Anneal | ≈ 980 °C | ≈ 1150 °C | ≈ 1150 °C |
| Normal service | up to 593 °C | above 593 °C | above 593 °C |
| Governing property | corrosion resistance | creep & rupture | creep & rupture |
| Relative cost | baseline | + small premium | + small premium |
When 800H is not enough
| Situation | Grade to consider | Why |
|---|---|---|
| Above ~1000 °C in air, structural | Inconel 617, Haynes 230 | Solid-solution Ni-Cr-Co / Ni-Cr-W with far higher rupture strength |
| Severe carburisation, cracking-tube service | HP-Nb cast alloys, Inconel 601 | Higher Ni + Si, or a cast microstructure designed for carbon pick-up |
| Oxidation above 1100 °C, unloaded | Alloy 602 CA, 601 | Aluminium-bearing chemistry forms a more stable scale |
| Combustion / gas-turbine hot section | Hastelloy X, N155 | Better strength and fabricability in thin hot-gas-path hardware |
| Wet acid or chloride corrosion, not heat | Incoloy 825, Hastelloy C-276 | 800H contains no molybdenum, so it is a heat alloy rather than an acid alloy |
| Below 593 °C, cost matters | Alloy 800, 321H / 347H stainless | 800H's creep advantage is not being used; you are paying for nothing |
🎯 800 / 800H / 800HT selector
ExclusiveThree questions decide which member of the family belongs on your drawing.
A selection aid, not a design calculation. The controlling document is always the applicable code and the end user's material specification.
Forging and heat treatment of UNS N08810
Alloy 800H is unforgiving of loose thermal control. The forging window is narrow at the bottom end, there is a band in the middle where the alloy must not be worked at all, and the final anneal is not a stress relief. It is the operation that creates the property the customer is paying for. Skip or under-temperature the anneal and the forging will still pass a tensile test and still fail in creep.
Figure 1. Thermal route of an alloy 800H forging. The shaded band is the working window; the anneal peak is what produces the ASTM 5 grain size.
| Operation | Parameter | Reason |
|---|---|---|
| Ingot / billet soak | 1150–1200 °C | Uniform through-heat before the first blow; controlled ramp to avoid cracking |
| Hot working range | 1200 → 870 °C | Heavy reduction taken in the upper part of the range |
| Prohibited working band | 650–870 °C | Cracking risk and poor resulting structure, so reheat rather than continue |
| Finish temperature | > 870 °C | The alloy work-hardens rapidly; finishing cold ruins the part |
| Forging reduction ratio | ≥ 3:1 (4:1 pressure parts) | Closes the as-cast structure and develops grain flow |
| Solution anneal | ≈ 1150 °C (2100 °F) | Dissolves carbides and grows grain to ASTM 5 or coarser |
| Cooling from anneal | Rapid, by water quench or forced air depending on section | Holds carbon in solution; avoids sensitisation on cooling |
| Soak time rule of thumb | 1 h per 25 mm of ruling section | Minimum 30 min; measured at temperature, not from door-close |
| Stress relief after welding | ≈ 900 °C, or full re-anneal | Applied when the customer specifies uniform properties across the weld |
| Descaling | Pickling after annealing | Chromium oxidises readily, so bright annealing is not practical in a normal furnace |
| Hardening response | None by heat treatment | Strengthened only by solid solution, carbon and cold work |
Because chromium oxidises readily in air, carbon dioxide and water vapour, 800H cannot be bright annealed in an ordinary industrial furnace. Annealing is done in box or bogie furnaces under a prepared reducing atmosphere, leaving the thin green-black oxide film that is then pickled off.
Grain size, the requirement most orders forget
On alloy 800H, grain size is a specification requirement with the same standing as the chemistry. ASTM B564 requires an average grain size of ASTM No. 5 or coarser for N08810, measured to ASTM E112. Two forgings from the same heat, with identical certificates on chemistry and tensile, can differ several times over in creep life purely on grain size.
What goes wrong
- Annealing at 980 °C, the alloy 800 recipe, instead of 1150 °C. The part recrystallises fine and never grows.
- Heavy finish reduction at low temperature followed by a short anneal.
- Thin sections cooling below the working range before the last pass, then being annealed on the standard stainless cycle.
How we control it
- Bogie-hearth furnace with ±5 °C uniformity and chart recording on every anneal cycle.
- Soak time set from the ruling section, not from the nominal drawing thickness.
- Grain size measured to ASTM E112 on a mounted, etched section and reported on the certificate as a number, not as "satisfactory".
Put it on the order. "Average grain size ASTM No. 5 or coarser per ASTM E112, reported on the certificate" is one line, and it is the line that separates a real 800H forging from a cheaper one that will pass incoming inspection and disappoint in year three.
📏 Thermal-expansion calculator for alloy 800H
ExclusiveFurnace hardware, reformer headers and hot flanges all grow. Enter the cold dimension and the operating temperature to get the growth and the hot dimension, using published mean expansion coefficients for alloy 800H.
Uses mean coefficients from 20 °C, interpolated: 14.4 µm/m·K to 100 °C rising to about 18.7 µm/m·K to 1000 °C. Real growth depends on restraint, gradient and creep relaxation, so treat this as a first estimate for clearance and expansion-joint sizing, not as a stress analysis.
Oxidation, carburisation and sulfidation resistance
Alloy 800H survives hot gas because chromium forms a tight, adherent oxide that slows further attack. What matters in practice is which of the three high-temperature degradation mechanisms your plant actually has.
| Mechanism | 800H behaviour | Practical limit / watch-out |
|---|---|---|
| Oxidation (air, CO₂, steam) | Good, protective Cr-rich scale, green-black film | Used in air to about 1100 °C for unloaded hardware; scale spalls under severe cycling |
| Carburisation (cracking furnaces, endogas, reformers) | Good resistance for a wrought alloy at this price | Carbon pick-up embrittles over time; very severe duty goes to cast HP-Nb or higher-Ni grades |
| Sulfidation (sulfur-bearing flue gas) | Moderate, better than low-nickel steels and worse than high-Cr grades | Nickel sulfide eutectics form at low temperature; keep sulfur activity in mind |
| Nitriding | Moderate | Nitrogen ingress hardens and embrittles the surface layer over long exposure |
| Thermal cycling | Helped by the low expansion coefficient | Less scale spalling than 300-series stainless in batch furnace duty |
| Chloride stress-corrosion cracking (cold end) | Good, and the nickel content is what provides it | Distinctly better than 304/316 in chloride-bearing condensate |
| Wet acid corrosion | Outside its scope, no molybdenum in the chemistry | For acid duty specify 825 or C-276 |
| Molten salt / molten metal | Not recommended | Requires a duty-specific alloy and a separate assessment |
Sigma phase. Unlike many Fe-Cr-Ni alloys, 800H does not form embrittling sigma phase in normal service, which is a large part of why it holds up over decades in reformer and cracking service rather than merely surviving a first campaign.
Welding and machining alloy 800H
Welding
Alloy 800H is readily welded by GTAW, GMAW, SMAW and SAW. Joint cleanliness matters more than technique: sulfur, lead, zinc and low-melting contaminants cause hot cracking in nickel alloys, so degrease and wire-brush with stainless brushes before striking an arc.
| Filler | Spec | Use it when |
|---|---|---|
| ERNiCr-3 (alloy 82) / ENiCrFe-3 (182) | AWS A5.14 / A5.11 | General fabrication, the default choice |
| ERNiCrCoMo-1 (alloy 617) | AWS A5.14 | Maximum elevated-temperature strength required across the joint |
| RA330-04 (N08334) | proprietary | Closer thermal-expansion match, somewhat higher strength |
| ERNiCrFe-11 / matching 800H wire | by agreement | Where the end user requires a matching-composition deposit |
- Heat input: keep it controlled and interpass temperature low; the alloy does not need preheat.
- PWHT: not mandatory for 800H. Apply a solution anneal at ≈1150 °C when uniform properties across weld and base metal are specified, or a ≈900 °C treatment where the fabrication cannot take a full anneal.
- Note for 800HT / N08811: to avoid stress-relaxation cracking at grain boundaries above about 540 °C, welded fabrications are commonly heated to ≈900 °C for one hour per inch of thickness, 30 minutes minimum, then air cooled.
Machining
800H machines much like austenitic stainless grades 302, 303, 410, 420, 430 and 430F, but at higher strength and with faster work hardening. Four rules cover most of it:
- Positive, uninterrupted cuts. Dwelling or rubbing work-hardens the surface and the next pass fights a harder skin than the one before.
- Rigid setups, sharp tooling, slower speeds, heavier feeds, flood coolant.
- Generous finishing stock. Forge skin and residual oxide are abrasive.
- Machine after annealing wherever the sequence allows, so you are cutting stable material.
Production capability of an Incoloy 800H forging manufacturer
Jiangyin Jiangnan Metal Co., Ltd. has forged open-die parts and seamless rolled rings at Zhouzhuang Town, Jiangyin since 2008, exporting to more than 40 countries. Nickel alloys including UNS N08810 are run on dedicated tooling and in clean furnace atmospheres to avoid sulfur pick-up and cross-contamination from carbon-steel production.
Equipment used for UNS N08810
| Operation | Equipment | Capability for alloy 800H |
|---|---|---|
| Open-die forging, heavy | 40 MN free-die hydraulic press | Discs to Ø1,800 mm; shafts to 8 m; single pieces to 8,000 kg |
| Open-die forging, medium | 25 MN free-die hydraulic press | Bars, sleeves, blocks; faster cycle, tighter reduction control |
| Ring rolling | Radial-axial ring mill | OD 200–2,500 mm, height to 600 mm, minimum wall 30 mm |
| Reheating | Gas-fired chamber furnaces with recorded cycles | 1150–1200 °C soak; pass schedules planned around reheats, not falling heat |
| Solution annealing | Bogie-hearth furnace, ±5 °C uniformity | ≈1150 °C with chart recording; quench tank alongside the door |
| Chemistry | Optical emission spectrometer | Full product analysis, calibrated daily, including the 0.05–0.10 % carbon window |
| Mechanical testing | Universal testing machine, hardness testers | Tensile per ASTM E8/E8M; elevated-temperature tensile on request |
| Metallography | Mount, polish, etch, image analysis | Average grain size to ASTM E112, reported as a number |
| NDE | Ultrasonic flaw detection, penetrant line | UT per EN 10228-3 / SEP 1921 / ASTM A388; PT per ASTM E165 (MT not applicable, non-magnetic) |
| Machining | CNC lathes, boring mills, machining centres | Rough machining with agreed allowance, or finish machined to drawing |
⚖️ Forging weight calculator for alloy 800H
ExclusiveNickel-alloy forgings are quoted per kilogram, so weight is price. Enter the finished dimensions and the tool returns finished weight, the input weight we would start from, and the buy-to-fly ratio. Density 7.94 g/cm³.
Geometric estimate only. Actual input weight depends on the forging route, test prolongations, crop ends and the ring-mill pre-form. Send the drawing and we will return the real input weight with the quotation.
🔥 Heat-treatment recipe for UNS N08810
ExclusiveEnter the ruling section, meaning the thickest part of the forging that has to reach temperature. The tool returns the anneal cycle we would run, in wording you can paste straight into a purchase order.
Indicative practice for open-die forgings in this alloy. The governing document is the customer's specification or the applicable ASTM / ASME requirement; cycles are agreed before production and recorded on a chart for every batch.
Quality, testing and certification
Every UNS N08810 forging leaves the works with a traceable heat number and a certificate that reports measured values. Standard scope is below; anything in the optional list is added without argument if it is on the purchase order.
Standard scope
- Chemical analysis, ladle and product, element by element
- Room-temperature tensile per ASTM E8/E8M
- Hardness survey
- Average grain size to ASTM E112, reported as a number
- Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388
- Dimensional inspection against the approved drawing
- Heat-treatment chart record
Optional on request
- Liquid penetrant testing per ASTM E165 / E1417
- Elevated-temperature tensile and stress-rupture testing
- Micro and macro examination, replication
- Positive material identification (PMI)
- Impact testing, intergranular corrosion testing
- Third-party witness and release by TÜV, SGS, BV, Lloyd's Register or your own inspector
Documentation. EN 10204 3.1 inspection certificate as standard, or 3.2 countersigned by an independent third party. Certificates state heat number, specification, delivery condition, grain size, all test results, and country of melt and origin.
Magnetic particle inspection cannot be used on this alloy. Alloy 800H is non-magnetic. If your NDE plan says "MT", the order stops at the inspection stage. Specify liquid penetrant testing instead.
Where alloy 800H forgings are used
800H earns its cost in one situation: sustained high temperature where a cheaper austenitic stainless would creep, carburise or scale. These are the duties our N08810 forgings go into.
| Industry | Components forged in 800H |
|---|---|
| Petrochemical | Ethylene cracking furnace hardware, transfer-line components, quench-exchanger parts, flanges and header rings |
| Hydrogen / ammonia / methanol | Steam-reformer outlet headers, pigtail and manifold connections, catalyst-tube hardware |
| Pressure vessels & heat exchangers | Tube sheets, shell rings, nozzles, closure heads, weld-neck and blind flange blanks |
| Power generation | Superheater and reheater components, steam-side headers, boiler penetrations, turbine and compressor parts |
| Heat-treatment plant | Retorts, muffles, radiant-tube components, furnace fixtures, roller shafts, hearth and basket hardware |
| Chemical process | Columns, towers, preheaters, crystalliser parts, agitator shafts, chemical and plunger pump components |
| Valves & flow control | Bodies, bonnets, seat rings, blocks and stems for high-temperature ball, gate, globe, check and plug valves |
| Nuclear & research | High-temperature gas-cooled reactor components under ASME Section III where 800H is qualified |
| Heavy industry | Mill rolls, forged wheels, manifolds and nozzles for cement, sugar, pulp and paper plant |
How to specify an 800H forging in seven lines
An enquiry with these seven lines can be quoted immediately and cannot be disputed at inspection. Anything missing turns into an email exchange and a slower quote.
Generic designation
Write UNS N08810, not the trademark. No supplier can then be rejected on brand grounds.
Product specification
ASTM B564 for forgings (B408 bar, B409 plate). Add the ASME SB- prefix and Code Case 1325 for code work.
Grain size
"Average grain size ASTM No. 5 or coarser per ASTM E112, reported on the certificate."
Delivery condition
"Solution annealed ≈1150 °C, rapid cooled, chart recorded." State rough or finish machined.
Dual certification
State whether you want 800H/HT dual certification. It costs little and keeps the design flexible.
Test scope + coupon
Tensile, hardness, grain size, UT class, and where the coupon is taken on heavy sections.
Certificate type
EN 10204 3.1, or 3.2 with the third-party inspector named on the order.
Seven mistakes that cost money on 800H orders
- Ordering "Incoloy 800H" on the purchase order. INCOLOY® is a Special Metals trademark; strictly read, that order can only be filled by them. Specify UNS N08810 and no one has grounds to reject the material.
- Leaving the grain-size requirement off the order. This is the most expensive omission on the grade. Without "ASTM No. 5 or coarser per ASTM E112" you can receive a chemically compliant forging with a fraction of the creep life you designed for.
- Accepting a certificate showing 0.03 % carbon. That is alloy 800, not 800H. On this grade a low carbon result is a failure, not a bonus.
- Requesting magnetic-particle inspection. The alloy is non-magnetic, so MT cannot be performed. Specify liquid penetrant instead, or the order stalls at inspection.
- Specifying 800H below 593 °C. Nothing is gained. Alloy 800, 321H or 347H does the same job for less money, and the creep premium is never used.
- Using 800H for wet acid service. There is no molybdenum in the chemistry. For acid or chloride pitting duty specify Alloy 825 or Hastelloy C-276.
- Buying a solid billet for a deep-bored part. At nickel-alloy prices a trepanned or forged-hollow blank commonly saves 40–60 % of the material weight on sleeves and hollow shafts.
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Glossary
| Term | Definition |
|---|---|
| UNS N08810 | Unified Numbering System designation for the nickel-iron-chromium alloy commonly called 800H. The correct wording for purchase orders. |
| UNS N08811 | Alloy 800HT, the same alloy with carbon 0.06–0.10 % and aluminium plus titanium narrowed to 0.85–1.20 %. |
| W.Nr. 1.4958 | German Werkstoff (material) number for alloy 800H; written X5NiCrAlTi31-20 on EN documents. |
| Creep | Slow, permanent deformation under constant load at high temperature. Above roughly 593 °C it, not yield strength, governs the design of 800H parts. |
| Stress rupture | Failure after a defined time at a given stress and temperature. Reported as, for example, the stress to cause rupture in 100,000 hours at 800 °C. |
| ASTM grain size No. 5 | A grain-size index from ASTM E112. Lower numbers mean coarser grain. 800H requires No. 5 or coarser, meaning 5, 4, 3 or 2, and not 6 or 7. |
| Solution annealing | Heating to about 1150 °C to dissolve carbides and grow the grain, then cooling rapidly. It is the delivery condition for 800H and the operation that creates its creep strength. |
| Sensitisation | Chromium carbide precipitation at grain boundaries leaving chromium-depleted zones. Controlled in 800H by rapid cooling from the anneal. |
| Carburisation | Carbon pick-up from the process gas into the metal at high temperature, forming carbides that embrittle the section. The dominant damage mechanism in cracking furnaces and reformers. |
| Sigma phase | A brittle intermetallic that forms in many Fe-Cr-Ni alloys on long exposure. Alloy 800H is largely free of it in normal service, which is a major reason for its long plant life. |
| ASME Code Case 1325 | The Code Case that approved higher design stresses for controlled-carbon, coarse-grained alloy 800. It is the document that effectively created the designation "800H". |
| Table UNF-23.2 | The ASME Section VIII Division 1 table of maximum allowable stresses for non-ferrous materials, which lists 800H / 800HT up to 816 °C (1500 °F). |
| Open-die forging | Hot forging between flat or simple dies that do not enclose the workpiece; used for shafts, discs, blocks and hollow parts and for sizes beyond closed-die capacity. |
| Seamless rolled ring | A ring produced by piercing a forged billet and rolling it out on a ring mill, giving continuous circumferential grain flow and no weld seam. |
| Ruling section | The thickest cross-section that must reach temperature during heat treatment; it sets soak time and cooling severity. |
| Reduction ratio | The ratio of starting cross-section to finished cross-section. Minimum 3:1 as standard, 4:1 or more for pressure-containing parts. |
| EN 10204 3.1 / 3.2 | Certificate types. 3.1 is issued by the manufacturer's independent quality department; 3.2 is countersigned by a third-party inspector nominated by the purchaser. |
| Dual certification | Material meeting both 800H and 800HT limits, certified to both UNS numbers on one document. |
Frequently asked questions about Incoloy 800H / UNS N08810
What is Incoloy 800H?
Incoloy 800H (Alloy 800H, UNS N08810, W.Nr. 1.4958) is a nickel-iron-chromium alloy with nominally 30–35 % nickel, 19–23 % chromium and a minimum of 39.5 % iron. It has the same base composition as Incoloy 800 but with carbon fixed at 0.05–0.10 % and an average grain size of ASTM No. 5 or coarser produced by a high-temperature anneal. Those two controls give it far higher creep and stress-rupture strength above 593 °C.
What is the difference between Incoloy 800, 800H and 800HT?
Alloy 800 (N08800) has 0.10 % carbon maximum with no lower limit, no grain-size requirement, and is normally used up to 593 °C. Alloy 800H (N08810) fixes carbon at 0.05–0.10 % and requires ASTM grain size 5 or coarser. Alloy 800HT (N08811) narrows carbon to 0.06–0.10 % and controls aluminium plus titanium to 0.85–1.20 %. Material meeting both 800H and 800HT limits is supplied dual certified as 800H/HT.
Which standard covers Incoloy 800H forgings?
ASTM B564 (ASME SB-564), Standard Specification for Nickel Alloy Forgings, covers UNS N08810. Related specifications are ASTM B408 for rod and bar, ASTM B409 for plate, sheet and strip, ASTM B407 for seamless pipe and tube, ASTM B366 for fittings and ASTM B472 for billets for reforging. Jiangyin Jiangnan Metal Co., Ltd. supplies 800H forgings to ASTM B564 with EN 10204 3.1 or 3.2 certification.
What is the maximum service temperature of Incoloy 800H?
Alloy 800H is selected for service above 593 °C (1100 °F), where creep governs. The ASME Boiler and Pressure Vessel Code tabulates maximum allowable stresses for 800H and 800HT in Section VIII Division 1, Table UNF-23.2, up to 816 °C (1500 °F), higher than almost any other alloy in that table. For unpressurised furnace hardware the alloy is used in air to about 1100 °C, where oxidation rather than strength sets the limit. Always confirm the allowable stress for your design temperature against the current Code edition.
What is the chemical composition of UNS N08810?
Nickel 30.0–35.0 %, chromium 19.0–23.0 %, iron 39.5 % minimum, carbon 0.05–0.10 %, aluminium 0.15–0.60 %, titanium 0.15–0.60 %, aluminium plus titanium 0.30–1.20 %, manganese 1.50 % maximum, silicon 1.00 % maximum, copper 0.75 % maximum, sulfur 0.015 % maximum.
Why does Incoloy 800H need a coarse grain size?
Above roughly half the melting point, creep damage accumulates by grain-boundary sliding and cavitation, so fewer grain boundaries means more creep life. ASTM B564 therefore requires an average grain size of ASTM No. 5 or coarser for N08810, developed by annealing at about 1150 °C. A fine-grained forging can meet every chemistry limit and still be correctly rejected as 800H.
What forging temperature range is used for Incoloy 800H?
Hot working runs between approximately 1200 and 870 °C (2200–1600 °F), with heavy reduction taken in the upper part of the range. The alloy should not be worked between about 650 and 870 °C. Because 800H work-hardens rapidly, reheating between passes is normal rather than finishing on a falling heat.
Is Incoloy 800H magnetic?
No. Alloy 800H has a stable austenitic face-centred-cubic structure and is essentially non-magnetic at room temperature, with a Curie temperature around −115 °C. A practical consequence is that magnetic-particle inspection cannot be performed. Specify liquid penetrant testing instead.
Can Incoloy 800H be welded?
Yes, by GTAW, GMAW, SMAW and SAW. Common filler metals are ERNiCr-3 / ENiCrFe-3 (alloy 82 / 182) for general work, ERNiCrCoMo-1 (alloy 617) where maximum elevated-temperature strength is needed, and RA330-04 where a closer thermal-expansion match is wanted. Post-weld solution annealing is not mandatory but is applied when uniform properties across weld and base metal are specified.
What is the DIN or EN equivalent of Incoloy 800H?
Werkstoff number 1.4958, designation X5NiCrAlTi31-20. For reference, alloy 800 is 1.4876 (X10NiCrAlTi32-21) and alloy 800HT is 1.4959 (X8NiCrAlTi32-21). Related national designations include BS NA15 and AFNOR Z8NC33-21.
Which forged shapes can be produced in Incoloy 800H?
Jiangyin Jiangnan Metal Co., Ltd. forges UNS N08810 into seamless rolled rings from 200 to 2,500 mm outside diameter, forged discs and tube sheets to Ø1,800 mm, shafts to 8 m, sleeves and hollow bars, flange blanks, valve bodies, blocks and round bars from 25 to 500 mm diameter, up to 8,000 kg single-piece weight.
What inspection and certification is supplied with 800H forgings?
Standard scope is chemical analysis, room-temperature tensile testing to ASTM E8/E8M, hardness, average grain size to ASTM E112 and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. Liquid penetrant testing, elevated-temperature tensile, stress-rupture testing and positive material identification are available on request. Documentation is EN 10204 3.1 as standard, or 3.2 witnessed by TÜV, SGS, BV or Lloyd's Register.
Who supplies Incoloy 800H forgings in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forging UNS N08810 rings, discs, tube sheets, shafts, flanges and bars to ASTM B564 since 2008 and exporting to more than 40 countries. Enquiries: sales@steelforgepieces.com, telephone +86-189-2135-9659.
How is the price of an Incoloy 800H forging calculated?
Price is quoted per kilogram of finished forging and driven by four things: the nickel and chromium raw-material index at the time of order, the input weight once forging and machining allowances are added, the number of press and reheat operations the shape needs, and the testing and certification scope. Send a drawing or the raw dimensions with quantity and specification for a quotation, normally within 24 hours.
Should I use 800H or 800HT?
For most pressure and furnace applications 800H is sufficient and is the cheaper, more available grade. Specify 800HT when the design leans on the upper end of the creep-rupture curve, when the end user's standard names N08811, or when the fabrication may later be requalified at a higher temperature. Ordering dual-certified 800H/HT keeps both options open at little or no extra cost, and is what we recommend on most enquiries.
Cite this page
This page is maintained as a technical reference by the engineering team at the forge. If you use the data in a specification, report, tender document or answer, please cite it as:
Jiangyin Jiangnan Metal Co., Ltd. (2026) "Incoloy 800H / Alloy 800H / UNS N08810
Forging Parts: composition, properties, creep behaviour, forging and heat treatment."
Updated 16 August 2026.
https://www.steelforgepieces.com/Nickel-Alloy/Incoloy-800H.html
Corrections and additions are welcome. If you have measured data for alloy 800H that contradicts anything here, write to sales@steelforgepieces.com and we will review the page and credit the correction.
Standards and references
Chemistry, mechanical, heat-treatment and code data on this page are drawn from the published standards and industry references below. Values on any individual certificate are our own test results, traceable to calibrated equipment.
- ASTM B564, Standard Specification for Nickel Alloy Forgings, ASTM International, West Conshohocken, PA.
- ASTM B408, Standard Specification for Nickel-Iron-Chromium Alloy Rod and Bar, ASTM International.
- ASTM B409, Standard Specification for Nickel-Iron-Chromium Alloy Plate, Sheet, and Strip, ASTM International.
- ASTM B407, Standard Specification for Nickel-Iron-Chromium Alloy Seamless Pipe and Tube, ASTM International.
- ASTM B472, Standard Specification for Nickel Alloy Billets and Bars for Reforging, ASTM International.
- ASTM B366, Standard Specification for Factory-Made Wrought Nickel and Nickel Alloy Fittings, ASTM International.
- ASTM E112, Standard Test Methods for Determining Average Grain Size, ASTM International.
- ASTM E8/E8M, Standard Test Methods for Tension Testing of Metallic Materials; ASTM E139, creep and stress-rupture testing; ASTM E165 / E1417, liquid penetrant testing; ASTM A388, ultrasonic examination of forgings.
- ASME Boiler and Pressure Vessel Code, Section VIII Division 1, Table UNF-23.2 (maximum allowable stresses, non-ferrous materials); Section I; Section III.
- ASME Code Case 1325, Nickel-Iron-Chromium Alloys 800 and 800H (UNS N08800 and N08810).
- EN 10228-3, Non-destructive testing of steel forgings, Ultrasonic testing; SEP 1921, ultrasonic testing of forgings.
- EN 10204, Metallic products, Types of inspection documents, CEN, Brussels.
- AWS A5.14 (ERNiCr-3, ERNiCrCoMo-1) and AWS A5.11 (ENiCrFe-3), filler metal specifications, American Welding Society.
- Special Metals Corporation, INCOLOY® alloys 800H and 800HT® product literature (UNS N08810 / N08811).
- ASM Handbook, Volume 13B, Corrosion: Materials, and Volume 14A, Metalworking: Bulk Forming, ASM International, Materials Park, OH.
Standards are referenced without an edition number because editions change; for procurement, always cite the revision in force at the contract date. All trademarks belong to their respective owners.
Request a quotation for Incoloy 800H / UNS N08810 forgings
Jiangyin Jiangnan Metal Co., Ltd.
Open-die forging factory · seamless rolled rings · forged discs, tube sheets, shafts and sleeves
📍 No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
📞 0086-189-2135-9659
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Send with your enquiry
- Drawing or dimensions, and quantity
- Specification: UNS N08810 / ASTM B564 / ASME SB-564
- Grain size requirement: ASTM No. 5 or coarser per ASTM E112
- Delivery condition and machining allowance
- Certificate level and inspection body if witnessed
- Design temperature, and design life if the part is pressure-retaining
- Required delivery date, Incoterm and destination