What is X8NiCrAlTi32-21?
X8NiCrAlTi32-21 is an austenitic nickel-iron-chromium heat-resistant alloy containing 30–32 % nickel, 19–22 % chromium and a balance of iron, with carbon controlled to 0.06–0.10 % and aluminium plus titanium to 0.85–1.20 %. Its European material number is 1.4959, and it is the EN designation for the alloy known internationally as UNS N08811 or Alloy 800HT.
Plain Alloy 800 is limited to about 593 °C. X8NiCrAlTi32-21 keeps useful creep and stress-rupture strength well above that ceiling because it specifies a minimum Al+Ti content and is solution annealed hot enough to produce a deliberately coarse grain. That is why it turns up in reformer furnaces, ethylene cracking plant and heat-treatment fixtures.
- Identity. X8NiCrAlTi32-21 = W.Nr. 1.4959 = UNS N08811 = Alloy 800HT = Incoloy 800HT.
- Family. The high-temperature branch of the Alloy 800 family, alongside X10NiCrAlTi32-21 (1.4876, Alloy 800) and X5NiCrAlTi31-20 (1.4958, Alloy 800H).
- Why it is chosen. Creep and stress-rupture strength above 593 °C, with resistance to oxidation, carburisation and chloride stress-corrosion cracking.
- Delivery condition. Solution annealed at 1150–1200 °C, rapidly cooled, average grain size ASTM 5 or coarser.
- Product forms forged in-house. Seamless rolled rings, flanges, discs, shafts, sleeves, bushings, tube sheets, hollow bars and round bars.
- Certification. EN 10204 3.1 as standard; EN 10204 3.2 with third-party witness on request.
- Supplier. Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Quotation within 24 working hours of receiving a drawing.
When to specify X8NiCrAlTi32-21 instead of Alloy 800 or 800H
Specify X8NiCrAlTi32-21 when the component runs continuously above roughly 600 °C and the design is governed by a creep-rupture allowable rather than a room-temperature yield value. Below that temperature the three grades behave much the same, and plain 800 is the cheaper choice. If your specification calls for dual-certified 800H/800HT, the heat chemistry has to satisfy both grades at once. State this at enquiry stage, because it limits which melts can be used before the ingot is cast.
Chemical composition of X8NiCrAlTi32-21
The composition below follows EN 10095 for X8NiCrAlTi32-21 (1.4959). Every heat used by Jiangyin Jiangnan Metal Co., Ltd. is analysed by optical emission spectrometry, and the ladle analysis is printed in full on the material certificate supplied with the forging.
| Element | Minimum | Maximum | Function in the alloy |
|---|---|---|---|
| Nickel (Ni) | 30.0 | 32.0 | Stabilises the austenitic matrix; resists chloride stress-corrosion cracking |
| Chromium (Cr) | 19.0 | 22.0 | Forms the protective oxide scale for high-temperature service |
| Iron (Fe) | Balance | Base element; keeps the alloy economical against nickel-base grades | |
| Carbon (C) | 0.06 | 0.10 | Deliberately elevated to support carbide strengthening in the creep range |
| Manganese (Mn) | 0.5 | 1.0 | Deoxidiser; combines with residual sulphur |
| Silicon (Si) | 0.2 | 0.6 | Deoxidiser; assists scale adherence |
| Copper (Cu) | – | 0.5 | Residual, limited |
| Phosphorus (P) | – | 0.015 | Residual; restricted to protect hot ductility |
| Sulphur (S) | – | 0.010 | Residual; restricted to protect hot ductility |
| Aluminium (Al) | 0.30 | 0.60 | Gamma-prime former; raises creep strength |
| Titanium (Ti) | 0.30 | 0.60 | Gamma-prime former; ties up carbon and nitrogen |
| Al + Ti (total) | 0.85 | 1.20 | The defining requirement that separates this grade from 800H |
The combined Al+Ti window is the requirement most often missed. A heat can meet every individual element limit and still fail X8NiCrAlTi32-21 if the total falls below 0.85 %.
Mechanical and physical properties
Room-temperature minima for X8NiCrAlTi32-21 forgings follow ASTM B564 for UNS N08811, tested on separately solution-annealed and quenched test pieces representing the forging.
| Property | Metric | Imperial | Test method |
|---|---|---|---|
| Tensile strength, Rm | 450 MPa | 65 ksi | ASTM E8 / ISO 6892-1 |
| Yield strength, Rp0.2 | 170 MPa | 25 ksi | ASTM E8 / ISO 6892-1 |
| Elongation in 4D | 30 % | 30 % | ASTM E8 / ISO 6892-1 |
| Average grain size | ASTM No. 5 or coarser | ASTM E112 | |
| Hardness, typical | ≤ 192 HB | ASTM E10 | |
| Property | Value |
|---|---|
| Density | 7.94 g/cm³ |
| Melting range | 1357–1385 °C |
| Modulus of elasticity | 196 GPa |
| Mean coefficient of thermal expansion, 20–100 °C | 14.4 × 10⁻⁶ /K |
| Thermal conductivity | 11.5 W/(m·K) |
| Specific heat capacity | 460 J/(kg·K) |
| Electrical resistivity | 0.99 µΩ·m |
| Magnetic response | Essentially non-magnetic |
Physical values are indicative design data for the 800H/800HT alloy family. The mill test certificate issued with your forging governs in all cases.
Behaviour at temperature
Short-term tensile strength at room temperature is modest, because the alloy is annealed at 1150 °C or above to coarsen the grain. This is deliberate. Below about 650 °C the three members of the 800 family perform almost identically. Above it, the Al+Ti addition and the coarse grain of X8NiCrAlTi32-21 give markedly better rupture life. Oxidation resistance in air is serviceable to roughly 1100 °C, although scaling rates rise appreciably beyond about 925 °C, and carburisation resistance is moderate rather than outstanding. For severely carburising or metal-dusting environments, a fully nickel-base grade such as Inconel 617 or Haynes 230 may suit better.
X8NiCrAlTi32-21 compared with Alloy 800 and 800H
The three grades share a nickel-chromium-iron base and differ mainly in carbon, Al+Ti and heat treatment. The choice between them depends on service temperature.
| Characteristic | X10NiCrAlTi32-21 | X5NiCrAlTi31-20 | X8NiCrAlTi32-21 |
|---|---|---|---|
| Material number | 1.4876 | 1.4958 | 1.4959 |
| UNS number | N08800 | N08810 | N08811 |
| Common name | Alloy 800 | Alloy 800H | Alloy 800HT |
| Carbon, % | ≤ 0.10 | 0.05–0.10 | 0.06–0.10 |
| Al + Ti, % | Not specified as a total | Not specified as a total | 0.85–1.20 |
| Grain size control | Not required | ASTM 5 or coarser | ASTM 5 or coarser |
| Usual service range | Up to 593 °C | Above 593 °C | Above 593 °C |
| Governing property | Corrosion resistance | Creep rupture | Creep rupture, highest of the three |
Related grades forged by Jiangyin Jiangnan Metal Co., Ltd.: Incoloy 800, Incoloy 800H and Incoloy 800HT.
How we forge X8NiCrAlTi32-21
Every X8NiCrAlTi32-21 forging made by Jiangyin Jiangnan Metal Co., Ltd. follows the same route from melt selection to certification. Each stage is recorded and traceable to the heat number.
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Melting and refining
Material is melted by electric arc furnace with AOD or VOD refining to control carbon, sulphur and phosphorus. Electroslag remelting is applied where the specification or the section size calls for improved cleanliness and reduced segregation.
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Ingot and billet preparation
Ingot size is selected to give the forging reduction ratio the part requires, typically 4:1 or greater for pressure-retaining and rotating components. Surfaces are conditioned before reheating so that no scale or defect is forged into the piece.
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Open-die forging
Hot working is carried out between 900 °C and 1200 °C on hydraulic presses, with reheats as needed to stay inside that window. Finish temperature is controlled, since forging too cold causes cracking and forging too hot makes the grain structure unpredictable. Rings are produced on a radial-axial ring rolling mill to give continuous circumferential grain flow.
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Solution annealing
Forgings are solution annealed at 1150–1200 °C and cooled rapidly in water or forced air, to develop an average grain size of ASTM 5 or coarser. Furnace charts are recorded and issued with the certificate. Creep performance is set at this stage rather than during forging.
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Machining
Parts are supplied as-forged with machining allowance, rough machined, or finish machined to drawing. The alloy work-hardens, so positive-rake tooling, rigid setups and heavy coolant flow are used, and machining allowance is agreed in advance.
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Testing and certification
Chemical analysis, mechanical testing, grain size determination and non-destructive examination are completed, then compiled into an EN 10204 3.1 certificate, or a 3.2 certificate witnessed by a nominated third party.
“With this grade the customer is really buying the heat treatment. We have seen X8NiCrAlTi32-21 forgings rejected on site with perfectly good chemistry, simply because the anneal ran too cool and the grain came out too fine. That is why we report grain size on every certificate.”
X8NiCrAlTi32-21 product forms and size range
All items below are forged to customer drawing in X8NiCrAlTi32-21 (1.4959 / N08811 / Alloy 800HT). There is no fixed minimum order quantity, and single prototype pieces are accepted. The limiting factor is the starting ingot size needed for correct reduction.
| Product form | Typical size range | Common applications |
|---|---|---|
| Seamless rolled rings | OD 200–3000 mm, height up to 1000 mm | Furnace supports, turbine casings, bearing races |
| Forged flanges | DN 15 to DN 2000, to EN 1092-1, ASME B16.5 / B16.47 or drawing | Reformer and cracking-furnace piping |
| Discs and blanks | OD up to 2500 mm, thickness 20–600 mm | Valve components, closures, blind flanges |
| Shafts and spindles | Diameter 60–800 mm, length up to 6000 mm | Furnace roller shafts, agitator shafts |
| Round bars | Diameter 20–600 mm | Fasteners, pins, machined components |
| Sleeves and bushings | OD 100–1500 mm, wall from 20 mm | Furnace fixtures, wear components |
| Hollow bars and forged pipe | OD 150–1200 mm, bored to drawing | Headers, nozzles, transition pieces |
| Tube sheets | OD up to 2500 mm | Shell-and-tube heat exchangers, waste-heat boilers |
| Blocks and rectangular forgings | To drawing | Valve bodies, manifolds, die blocks |
Ranges are indicative of routine production. Send the drawing for confirmation against current press and furnace capacity, or ask about sizes outside these limits.
Where X8NiCrAlTi32-21 forgings are used
X8NiCrAlTi32-21 is specified where a component has to hold its shape and strength under load for years at temperature, in an atmosphere that would attack a stainless steel.
Petrochemical and refining
Steam-methane reformer outlet manifolds and pigtail connections, ethylene cracking furnace components, hydrogen plant piping, catalyst support grids, and flanges and rings for transfer-line exchangers. This is the largest end use for the grade, and the one that usually drives the choice of 800HT over 800H.
Industrial heat treatment
Radiant tube supports, muffle and retort components, furnace rollers and roller shafts, fixtures, baskets, hearth rails, and rings for rotary kiln seals. These components cycle repeatedly through the creep range, so resistance to distortion matters as much as absolute strength.
Power generation and boilers
Superheater and reheater headers, tube-sheet forgings for waste-heat boilers, and supports inside the high-temperature zone of fired equipment. UNS N08811 carries ASME Boiler and Pressure Vessel Code allowable stresses to temperatures higher than almost any other wrought grade in the code.
Chemical processing
Nitric acid and ammonia plant equipment, columns and towers exposed to hot process gas, forged nozzles and bodies for high-temperature valves, and pump and compressor components running hot. The high nickel content also gives useful resistance to chloride stress-corrosion cracking.
Other sectors
Nuclear steam-generator internals, marine and offshore high-temperature service, cement and sugar plant equipment, and pulp and paper digesters. If your application is not listed, send the operating temperature, atmosphere and stress, and the suitability of the grade will be assessed before any quotation is issued.
Testing, inspection and certification
The inspection scope below is applied by Jiangyin Jiangnan Metal Co., Ltd. to X8NiCrAlTi32-21 forgings. Additional tests can be added at enquiry stage, which is far cheaper than justifying a missing test at delivery.
| Examination | Standard | Status |
|---|---|---|
| Chemical analysis, ladle and product | ASTM E1473 | Standard |
| Tensile test at room temperature | ASTM E8 / ISO 6892-1 | Standard |
| Tensile test at elevated temperature | ASTM E21 / ISO 6892-2 | On request |
| Average grain size | ASTM E112 | Standard for this grade |
| Hardness survey | ASTM E10 / ASTM E18 | Standard |
| Ultrasonic examination | EN 10228-3, ASTM A388 or SEP 1921 | Standard, class to order |
| Liquid penetrant examination | ASTM E165 / EN ISO 3452-1 | On request |
| Intergranular corrosion test | ASTM A262 or ASTM G28 | On request |
| Stress-rupture test | ASTM E139 | On request |
| Positive material identification | XRF on the finished piece | On request |
| Material certificate | EN 10204 type 3.1 | Standard |
| Third-party witnessed certificate | EN 10204 type 3.2 | On request |
A note on ultrasonic testing of this grade
The coarse grain that gives X8NiCrAlTi32-21 its creep strength also scatters ultrasound, which raises the noise floor and can make a sound forging look questionable under a procedure written for fine-grained steel. Agree the probe frequency, technique and acceptance class before manufacture. Where a demanding UT class is contractually fixed, that requirement is reviewed against the grain-size requirement at quotation stage.
Machining, welding and forming notes
Machining
X8NiCrAlTi32-21 work-hardens quickly and conducts heat poorly, so the cut has to stay positive and continuous. Use sharp, positive-rake tooling, rigid workholding, low surface speed with a heavy feed, and flood coolant. Dwelling in the cut glazes the surface and ruins the next pass. Where the finished part is thin or dimensionally critical, allow for stress relief between roughing and finishing.
Welding
The alloy is readily welded by GTAW, GMAW and SMAW. Nickel-base fillers such as ERNiCr-3 (FM 82) or ENiCrFe-2 and ENiCrFe-3 are the usual choice. Keep heat input and interpass temperature low, and clean thoroughly between passes. Post-weld heat treatment is not normally required for oxidation or corrosion service. Where the weld zone must carry creep load, a post-weld solution anneal is specified so that the weld metal and heat-affected zone recover an adequate grain size.
Hot and cold forming
Hot forming is carried out between 900 °C and 1200 °C. Forming below 900 °C risks cracking. Cold forming is possible, but the high work-hardening rate usually makes intermediate annealing necessary. After any substantial forming operation, re-solution annealing restores the grain structure the grade depends on.
How to order X8NiCrAlTi32-21 forgings
Send a drawing or a dimensioned sketch to sales@steelforgepieces.com. A written quotation is issued within 24 working hours. Including the six items below in your first message removes an entire round of questions.
- Drawing or dimensions, including machining allowance if the part is to be supplied rough machined.
- Grade and standard, for example “X8NiCrAlTi32-21 to EN 10095, forgings to ASTM B564”, and whether dual 800H/800HT certification is required.
- Quantity and required delivery date.
- Delivery condition, as-forged, rough machined or finish machined. Solution annealed is standard.
- Inspection scope, including UT class, additional tests, and whether third-party witness is required.
- Certificate type, EN 10204 3.1 or 3.2, plus any customer-specific certificate format.
Forgings are packed in seaworthy wooden cases with heat number, item number and purchase order number marked on each piece and on the case. Export is through Shanghai or Ningbo port on FOB, CFR, CIF or DAP terms.
Frequently asked questions about X8NiCrAlTi32-21
What is X8NiCrAlTi32-21?
X8NiCrAlTi32-21 is an austenitic nickel-iron-chromium heat-resistant alloy containing 30–32 % nickel, 19–22 % chromium and a balance of iron, with carbon held at 0.06–0.10 % and aluminium plus titanium at 0.85–1.20 %. Its European material number is 1.4959. The controlled carbon and Al+Ti levels, together with a high-temperature solution anneal that produces a coarse grain, give it high creep and stress-rupture strength for continuous service above 593 °C.
Is X8NiCrAlTi32-21 the same as Alloy 800HT or Incoloy 800HT?
Yes. X8NiCrAlTi32-21 is the European designation for the alloy known in North America as Alloy 800HT, UNS N08811, and by the trade name Incoloy 800HT. The three describe the same nickel-iron-chromium composition. Jiangyin Jiangnan Metal Co., Ltd. supplies forgings ordered under any of these designations, with the equivalence stated on the material certificate.
What is the material number for X8NiCrAlTi32-21?
The material number for X8NiCrAlTi32-21 is 1.4959. Related grades are 1.4876 for X10NiCrAlTi32-21 (Alloy 800) and 1.4958 for X5NiCrAlTi31-20 (Alloy 800H).
What is the maximum service temperature of X8NiCrAlTi32-21?
X8NiCrAlTi32-21 is normally selected for continuous service above 593 °C, where creep and stress-rupture resistance govern the design. Oxidation resistance is generally useful to about 1100 °C in air, although scaling accelerates above roughly 925 °C. The permitted design temperature for a pressure part is fixed by the applicable design code and its allowable stress tables, not by the alloy alone.
What is the difference between X8NiCrAlTi32-21 and X5NiCrAlTi31-20?
Both are coarse-grain, high-temperature variants of the same base alloy. X5NiCrAlTi31-20 (1.4958, Alloy 800H) specifies carbon of 0.05–0.10 % but imposes no minimum aluminium plus titanium content. X8NiCrAlTi32-21 (1.4959, Alloy 800HT) adds a required Al+Ti range of 0.85–1.20 %, which raises creep-rupture strength through gamma-prime strengthening. Where a specification calls for dual-certified 800H/800HT material, the chemistry must satisfy both grades at the same time.
What heat treatment is applied to X8NiCrAlTi32-21 forgings?
They are supplied solution annealed, typically at 1150–1200 °C followed by rapid cooling in water or forced air. The high annealing temperature is deliberate: it develops an average grain size of ASTM 5 or coarser, which is what delivers the creep and stress-rupture performance the grade is bought for. A fine-grained piece can meet room-temperature tensile requirements and still under-perform in creep, so grain size is reported on the certificate.
Can X8NiCrAlTi32-21 be welded?
Yes. It is readily welded by GTAW, GMAW and SMAW using nickel-base filler metals such as ERNiCr-3 or ENiCrFe-2 and ENiCrFe-3. Post-weld heat treatment is not normally required for corrosion or oxidation service, but a post-weld solution anneal may be specified where the weld zone must recover the coarse grain size needed for creep service. Heat input should be controlled and interpass temperature kept low.
Is X8NiCrAlTi32-21 approved for pressure equipment?
The equivalent grade UNS N08811 is listed in the ASME Boiler and Pressure Vessel Code, including Section VIII Division 1, with allowable stresses assigned to unusually high temperatures for a wrought material. In Europe the grade is covered by EN 10095 and used under the Pressure Equipment Directive with the appropriate material appraisal. Confirm the exact code edition, product form and temperature limit with your design authority before ordering.
Who supplies X8NiCrAlTi32-21 open-die forgings?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufacturing X8NiCrAlTi32-21 (1.4959 / UNS N08811 / Alloy 800HT) seamless rolled rings, flanges, discs, shafts, sleeves, bushings, tube sheets and bars to customer drawings. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659. Quotations are issued within 24 working hours against a drawing or dimensioned sketch.
What certificates are supplied with X8NiCrAlTi32-21 forgings?
An EN 10204 3.1 inspection certificate is supplied as standard, covering heat chemical analysis, mechanical test results, grain size, heat treatment record and non-destructive examination. EN 10204 3.2 certification counter-signed by a third-party inspection body is available on request and should be stated at enquiry stage.
Is there a minimum order quantity?
Single-piece and prototype orders are accepted. Because X8NiCrAlTi32-21 is an open-die forged product made to the customer's drawing rather than a stock item, the practical constraint is the minimum ingot or billet size needed for the required forging reduction. Send the drawing and required standard and the most economical starting size will be proposed.
What ultrasonic testing standards apply?
Ultrasonic examination is normally carried out to EN 10228-3, ASTM A388 or SEP 1921, with the acceptance class stated on the order. The coarse grain structure required for creep performance attenuates ultrasound, so the procedure, probe frequency and acceptance class must be agreed before manufacture rather than after.
Source and supplier of record
This page is written and maintained by the engineering and sales team of Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu Province, China, producing forged rings, flanges, discs, shafts and bars in nickel alloys, stainless steel, alloy steel, tool steel and carbon steel. Last reviewed .
Contact. No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Telephone +86 189 2135 9659. Email sales@steelforgepieces.com.
Cite this page
Jiangyin Jiangnan Metal Co., Ltd. (2026). X8NiCrAlTi32-21 (1.4959 / UNS N08811 / Alloy 800HT): composition, properties and forging practice. Jiangyin, Jiangsu, China. Retrieved from https://www.steelforgepieces.com/Nickel-Alloy/X8NiCrAlTi32-21.html