§01What NCF 800 is
NCF 800 is a solid-solution nickel-iron-chromium alloy standardised in Japan under the JIS superalloy series, where NCF stands for nickel, chromium and iron. The high nickel content is what gives it resistance to chloride stress-corrosion cracking. Chromium handles the oxidising side and forms the protective film that lets the alloy survive long exposures at temperature. Small controlled additions of aluminium and titanium, 0.15 to 0.60 % each, stabilise the carbides and stop the structure drifting during long-term heating.
The alloy is austenitic and does not harden by transformation, so forgings go out solution treated. Strength comes from composition and grain structure rather than from any heat-treat response. That puts a lot of weight on the forging route itself. How the ingot is broken down, how much reduction the part actually sees, and how it is annealed afterwards all show up in the properties you receive.
Buying note. NCF 800, UNS N08800 and Incoloy 800 share the same base chemistry, but your purchase order should still name the standard you want, for example ASTM B564 for forgings. Composition is only part of it. Standards also differ in test frequency, grain size and certification.
§02Chemical composition of NCF 800
This is the composition we supply NCF 800 forgings to. All values are weight percent.
| Limit | C | Si | Mn | P | S | Ni | Cr | Cu | Al | Ti | Fe |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | – | – | – | – | – | 30.00 | 19.00 | – | 0.15 | 0.15 | – |
| Max | 0.10 | 1.00 | 1.50 | 0.030 | 0.015 | 35.00 | 23.00 | 0.75 | 0.60 | 0.60 | Balance |
Iron is the balance. Where the order calls up UNS N08800 to ASTM B564, iron also has to be 39.5 % minimum. Name the governing standard on your enquiry and the heat will be selected accordingly.
§03Mechanical properties
Minimum room-temperature properties for NCF 800 in the solution-treated condition.
| 0.2 % proof strength (N/mm²) |
Tensile strength (N/mm²) |
Elongation (%) |
Hardness | |
|---|---|---|---|---|
| HV | HB | |||
| ≥ 205 | ≥ 520 | ≥ 30 | ≤ 182 | ≤ 179 |
1 N/mm² equals 1 MPa. In imperial units the minima work out at about 29.7 ksi proof and 75.4 ksi tensile. On heavy sections, properties are quoted at the test location agreed when the order is placed, so tell us the section thickness and we will confirm what is achievable before you commit.
§04Physical properties
Typical published values for Alloy 800 at room temperature. Use them for design estimating. The mill certificate governs whatever you actually receive.
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.94 g/cm³ | 0.287 lb/in³ |
| Melting range | 1357–1385 °C | 2475–2525 °F |
| Modulus of elasticity | 196 GPa | 28.5 × 10³ ksi |
| Specific heat | 460 J/kg·K | 0.11 Btu/lb·°F |
| Thermal conductivity | 11.5 W/m·K | 80 Btu·in/h·ft²·°F |
| Electrical resistivity | 0.99 µΩ·m | 595 Ω·circ mil/ft |
| Magnetic response | Non-magnetic when solution treated (austenitic structure) | |
§05Equivalent grades and standards
NCF 800 turns up under several national designations. The cross-reference below is for identifying material. It is not a statement that the grades are interchangeable in a pressure-retaining application.
| Country / system | Designation | Notes |
|---|---|---|
| Japan, JIS | NCF 800 | G 4901 bars, G 4902 plates, G 4903 pipes, G 4904 heat-exchanger tubes |
| USA, UNS | N08800 | The controlling designation on most international orders |
| Trade name | Incoloy 800 | Registered trade name. The generic term is Alloy 800 |
| ASTM / ASME | B564, B408, B409, B407 | B564 forgings, B408 bar, B409 plate, B407 pipe and tube, plus the ASME SB- equivalents |
| Europe, EN | 1.4876, X10NiCrAlTi32-21 | Material number and name designation |
| Germany, DIN | X10NiCrAlTi32-20 | Older designation, still seen on legacy drawings |
| UK, BS | NA 15 | Legacy designation |
| China, GB | NS1101 | Indicative equivalent. Confirm against the GB/T requirements |
§06NCF 800 vs 800H vs 800HT
This is where most Alloy 800 orders go wrong. The three grades share a base composition and are separated by carbon content, aluminium-plus-titanium content and grain size, which between them control creep behaviour.
| NCF 800 / Alloy 800 | Alloy 800H | Alloy 800HT | |
|---|---|---|---|
| UNS | N08800 | N08810 | N08811 |
| Carbon | 0.10 % max | 0.05 to 0.10 % | 0.06 to 0.10 % |
| Al + Ti | Not restricted as a sum | Not restricted as a sum | 0.85 to 1.20 % combined |
| Grain size | Not controlled | ASTM No. 5 or coarser | ASTM No. 5 or coarser |
| Chosen for | Corrosion and oxidation resistance in general service | Creep and stress-rupture strength | The most consistent creep-rupture strength of the three |
| Typical use | Sustained service to about 816 °C (1500 °F) | Sustained service above roughly 600 °C (1100 °F) | Sustained service above roughly 600 °C (1100 °F) |
Rule of thumb. If the design load is creep-controlled, say a reformer pigtail, a furnace hanger or a hot header, specify 800H or 800HT rather than plain 800. If the driver is corrosion, oxidation and chloride SCC resistance at moderate temperature, NCF 800 is the cheaper answer. We forge all three: Incoloy 800H and Incoloy 800HT.
§07Melting route, forging and heat treatment
Melting
NCF 800 for our forgings is melted by EAF plus VOD, then electro-slag remelted. Vacuum oxygen decarburisation brings carbon and gas content down without stripping chromium out of the bath. ESR then refines the ingot structure and cuts segregation and non-metallic inclusions, which is what makes heavy sections sound enough to pass ultrasonic examination.
Forging
Ingots are upset and drawn on open-die presses, then either mandrel-forged and ring-rolled for seamless rolled rings, or drawn down to bar and discs. Nickel-iron-chromium alloys have a narrower hot-working window than carbon steel and work-harden quickly, so reheating between passes and finishing temperature matter more here than they would on a comparable steel part.
Heat treatment
Standard delivery condition is solution treated, which dissolves the carbides and restores a uniform austenitic structure. We age after solution treatment where a customer specification calls for it, and we can hold material to a specified grain size when the order requires it.
§08Forged product forms
Everything below is made to customer drawing or to a written specification. There is no fixed catalogue, so send the drawing and we will confirm feasibility, forged weight and price.
Seamless rolled rings
Ring-rolled from a pierced preform. Used for shell courses, valve seat rings and bearing races.
Forged rings and sleeves
Upset and punched, for short runs or for wall thickness that ring rolling does not suit. Covers sleeves and bushings.
Flanges
Weld neck, slip-on, blind and special profiles to ASME B16.5, B16.47 or to drawing.
Round bars and shafts
Plain bar, stepped shafts, spindles, eccentric shafts and crankshafts.
Discs and tube sheets
Solid or bored discs, and heat-exchanger tube sheets.
Hollow bars, tubes and pipes
Forged and bored hollows for pressure parts where no seamless tube size exists.
Valve components
Bodies, bonnets, blocks, stems, seat rings and nozzles for ball, gate, globe, check and plug valves.
Blocks and near-net shapes
Rectangular blocks and profiled blanks, with machining allowance agreed in advance.
Maximum diameter and single-piece weight depend on the geometry and on the section you need through the part, so we confirm those against your drawing rather than quoting a blanket figure.
§09Where NCF 800 forgings are used
Petrochemical and refining
Heat-exchanger tube sheets, shell flanges, forged nozzles, columns and towers, preheaters and process modules.
Pressure vessels
Shell-and-tube heat exchangers, air receivers, forged tubes, tube sheets and vessel flanges.
Valves and flow control
Ball, gate, globe, check and plug valves: bodies, blocks, stems, seat rings and strainer parts.
Oil, gas and offshore
Subsea and deepwater production systems, wellhead and Christmas-tree components, industrial air compressors.
Power generation
Turbine parts, gas-compressor components, gearboxes, spindles and power-transmission gears.
Chemical processing
Chemical and plunger pump shafts, crystalliser equipment, tanks and silos.
Heavy machinery
Cement, sugar and concrete mills and mixers, forged rolls, wheels and manifolds.
Marine, pulp and pharma
Shipbuilding, pulp and paper plant, pharmaceutical and biochemical process equipment.
§10Testing, NDT and certification
Non-destructive testing
NCF 800 is austenitic, which matters when you write the UT clause. Coarse austenitic grain scatters sound, so acceptance standards written for ferritic forgings do not transfer cleanly. We normally examine NCF 800 forgings to ASTM A745/A745M or EN 10228-4, both of which were written for austenitic material. Where a customer specification calls up ASTM A388, EN 10228-3 or SEP 1921 we will work to it as specified, so state the class and acceptance level on the enquiry.
Liquid penetrant testing is available, along with magnetic particle examination where it applies, plus dimensional and visual inspection reports.
Destructive and chemical testing
- Chemical analysis by optical emission spectrometry, reported per heat
- Room-temperature tensile: 0.2 % proof strength, tensile strength, elongation
- Hardness in HB or HV
- Grain size determination where the order specifies it
- Intergranular corrosion testing, for example to ASTM G28, on request
Certification
Forgings ship with an EN 10204 3.1 mill certificate as standard. EN 10204 3.2 certification with third-party witness and countersignature is available on request, whether that is TÜV, SGS, BV, DNV, LR or the inspection body named in your order. Ask for it at enquiry stage so the witness points can be scheduled into production.
§11Our factory
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We sit in the Yangtze River delta forging cluster, roughly two hours from the ports of Shanghai and Ningbo. Nickel alloys, stainless steels, tool steels, alloy steels and carbon steels are all forged here to customer drawing.
| Forging processes | Open-die forging, ring rolling, upsetting, mandrel forging |
|---|---|
| Heat treatment | Solution treatment, ageing where specified, controlled grain size on request |
| Machining | Rough machining and finish machining to drawing |
| Materials | Nickel alloys, stainless steel, tool steel, alloy steel, carbon steel |
| Testing | Spectrometric analysis, tensile, hardness, grain size, UT, PT, MT |
| Certification | EN 10204 3.1 as standard, EN 10204 3.2 with third-party witness on request |
| Export markets | Worldwide, with documentation in English |
| Contact | sales@steelforgepieces.com, +86 189 2135 9659 |
§12How to order NCF 800 forgings
- Send the drawing or the dimensions. For rings, that is OD, ID and height. For bars, diameter and length. For flanges, the standard and rating, or a drawing. Email sales@steelforgepieces.com.
- State the specification. The governing standard, for example ASTM B564 UNS N08800, the delivery condition, any NDT class, and the certification level, 3.1 or 3.2 to EN 10204.
- Receive the quotation. We confirm feasibility, forged weight, price and delivery. If the geometry can be produced more economically another way, we will say so.
- Production and inspection. Melting, forging, heat treatment and testing, with third-party witness at the agreed hold points where 3.2 applies.
- Documentation and shipment. Mill certificate, test reports and packing list are issued with the shipment.
Lead time is confirmed with the quotation. It depends mainly on the size, the section thickness, and whether a suitable heat is available or has to be melted.
§13Frequently asked questions
What is NCF 800?
NCF 800 is the JIS designation for a nickel-iron-chromium alloy containing 30 to 35 % nickel, 19 to 23 % chromium and the balance iron, with controlled aluminium and titanium additions of 0.15 to 0.60 % each. It is used where equipment needs corrosion resistance, oxidation resistance and structural stability in service up to 816 °C (1500 °F).
Is NCF 800 the same as Incoloy 800 and UNS N08800?
They describe the same base alloy. NCF 800 is the Japanese JIS designation, UNS N08800 is the North American unified number, and Incoloy 800 is the trade name. The generic term is Alloy 800.
Composition limits come out the same, but test requirements and certification differ between standards. Name the standard on your order rather than relying on the grade name alone.
What is the maximum service temperature of NCF 800?
About 816 °C, or 1500 °F. For sustained service above roughly 600 °C (1100 °F) where the design is governed by creep or stress rupture, specify Alloy 800H (UNS N08810) or 800HT (UNS N08811) instead, because those grades control carbon content and grain size.
What is the difference between 800, 800H and 800HT?
Alloy 800 has a maximum carbon of 0.10 % with no grain size requirement. Alloy 800H requires carbon of 0.05 to 0.10 % and a grain size of ASTM No. 5 or coarser. Alloy 800HT adds a combined aluminium plus titanium requirement of 0.85 to 1.20 % on top of the 800H requirements, which is what gives it the most consistent creep-rupture strength of the three.
Which standards cover NCF 800 forgings?
For forgings the usual specification is ASTM B564, or ASME SB-564, for UNS N08800. Related product standards are ASTM B408 for bar, B409 for plate and B407 for pipe and tube. Under JIS, NCF 800 appears in G 4901 for bars, G 4902 for plates, G 4903 for pipes and G 4904 for heat-exchanger tubes. The European material number is 1.4876.
Is NCF 800 magnetic?
No. NCF 800 has a face-centred cubic austenitic structure and is non-magnetic in the solution-treated condition. Heavy cold work can produce a slight magnetic response at the worked surface.
Can NCF 800 be welded?
Yes, by GTAW, SMAW and other conventional processes, using nickel-based filler metals such as ERNiCr-3 or whatever your welding procedure names.
Keep interpass temperature controlled and heat input moderate, and clean the joint thoroughly. Nickel alloys are sensitive to sulphur and other low-melting-point contaminants, and marker pen or cutting fluid left on the prep is a common cause of cracking.
Does NCF 800 resist chloride stress-corrosion cracking?
The high nickel content gives it much better resistance than standard austenitic stainless steels such as 304 or 316, which is one of the main reasons it gets selected for heat exchangers and process equipment in chloride-bearing service. It is not immune, and severe conditions may call for a higher-nickel alloy.
What is the density of NCF 800?
7.94 g/cm³, or 0.287 lb/in³, with a melting range of roughly 1357 to 1385 °C. Use that figure when estimating forged weight from a drawing.
Who supplies NCF 800 forgings, and in what forms?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We produce NCF 800 forged rings, seamless rolled rings, flanges, round bars, discs, sleeves, bushings, tube sheets, shafts, valve components and forged pipes to customer drawing, with EN 10204 3.1 or 3.2 certification. Contact sales@steelforgepieces.com or +86 189 2135 9659 for a quotation.