Z8NC33-21
Z8NC33-21 is the French AFNOR name for a nickel iron chromium heat resistant alloy with about 33% nickel and 21% chromium. The same material is sold as Alloy 800H and is listed as UNS N08810 and W.Nr. 1.4958. Jiangyin Jiangnan Metal Co., Ltd. forges Z8NC33-21 to customer drawing at its open die plant in Jiangyin, Jiangsu Province, China. We make rings, flanges, discs, shafts, sleeves and tube sheets.
- AFNOR (France)
- Z8NC33-21
- UNS (USA)
- N08810
- Werkstoff-Nr.
- 1.4958
- EN steel name
- X5NiCrAlTi31-20
- Common trade name
- Alloy 800H
Z8NC33-21 at a glance
- Material family
- Austenitic nickel iron chromium heat resistant alloy
- Nominal composition
- 33% Ni, 21% Cr, balance Fe, with controlled aluminium and titanium
- Best known equivalent
- Alloy 800H, UNS N08810, W.Nr. 1.4958
- Melting route
- EAF with AOD or VOD refining, ESR remelting on request
- Delivery condition
- Solution annealed, rapid cooled
- Forged product forms
- Seamless rolled rings, flanges, discs, round bars, shafts, sleeves, bushings, hollow bars, tube sheets, blocks
- Single piece weight
- 5 kg to 20,000 kg
- Maximum ring OD
- 3,000 mm
- Ultrasonic testing
- EN 10228-3, SEP 1921 or ASTM A388, to the class you specify
- Certification
- EN 10204 3.1 mill certificate, or 3.2 with third party witness
- Typical service
- Continuous operation above 600 °C where creep and rupture strength govern
- Manufacturer
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin City, Jiangsu Province, China
Z8NC33-21 equivalent grades
The name comes from the AFNOR system. Z marks a high alloy or stainless grade. The first figure is the carbon content in hundredths of a percent. The letters are the main alloying elements and the figures after them give the percentages. Read that way, Z8NC33-21 is 0.08% carbon, 33% nickel and 21% chromium. That is why it lines up with Alloy 800H rather than with Alloy 800 or with a stainless steel.
| Standard or system | Country or region | Designation |
|---|---|---|
| AFNOR NF | France | Z8NC33-21 |
| UNS | United States | N08810 |
| Werkstoff-Nr. | Germany | 1.4958, also listed as 1.4876 |
| EN steel name | Europe | X5NiCrAlTi31-20 |
| BS | United Kingdom | NA 15(H) |
| JIS | Japan | NCF 800H |
| GOST | Russia | ХН32Т, ЭИ670 |
| Trade name | International | Incoloy® 800H, Alloy 800H |
Incoloy® is a registered trademark of the Special Metals Corporation group. Cross references are given for identification only. The governing specification is whatever your drawing and order call out.
How Z8NC33-21 differs from Alloy 800 and Alloy 800HT
All three grades use the same iron nickel chromium base. They differ in carbon, in grain size and in the combined aluminium and titanium content, and those three things set the creep behaviour. Alloy 800 (UNS N08800, 1.4876) has lower carbon and is normally kept below about 650 °C. Alloy 800H is the grade Z8NC33-21 matches. It carries more carbon and a coarse controlled grain size, which is what lets it run hotter. Alloy 800HT (UNS N08811, 1.4959) raises the aluminium and titanium minimums again for more creep rupture strength. If your drawing fixes an Al plus Ti range, tell us at enquiry. That one line decides which of the three we melt.
Chemical composition of Z8NC33-21
| Element | Minimum | Maximum |
|---|---|---|
| Carbon (C) | 0.06 | 0.10 |
| Silicon (Si) | – | 1.00 |
| Manganese (Mn) | – | 1.50 |
| Phosphorus (P) | – | reported on certificate |
| Sulphur (S) | – | 0.015 |
| Nickel (Ni) | 30.0 | 35.0 |
| Chromium (Cr) | 19.0 | 23.0 |
| Copper (Cu) | – | 0.75 |
| Aluminium (Al) | 0.15 | 0.60 |
| Titanium (Ti) | 0.15 | 0.60 |
| Iron (Fe) | 39.5 | balance |
A dash means the specification fixes no limit. The value is still determined and reported on the mill certificate. Where a drawing imposes a combined Al plus Ti range, we melt to that range and report it separately.
Mechanical and physical properties
The figures below are indicative room temperature values for solution annealed material in the Alloy 800H class. Acceptance is against the standard named on your order. The numbers that count are the ones on the mill certificate for your heat.
| Property | Value |
|---|---|
| Tensile strength, Rm | 450 MPa min (65 ksi) |
| Yield strength, Rp0.2 | 170 MPa min (25 ksi) |
| Elongation, A | 30% min |
| Hardness | 192 HB max, typical |
| Grain size | ASTM 5 or coarser |
| Density | 7.94 g/cm³ |
| Melting range | 1,357 to 1,385 °C |
| Solution anneal | about 1,150 °C, rapid cool |
Why Z8NC33-21 is specified
Nickel and chromium give the resistance to oxidation, carburisation, nitriding and chlorine attack. That is what makes this family the standard choice for furnace hardware and reformer service. Aluminium and titanium add sulphidation and oxidation resistance on top. The coarse grain and the higher carbon in the 800H variant are deliberate. They cost some room temperature ductility and buy creep and stress rupture strength at the temperature the part actually runs at.
Z8NC33-21 forged products we make
Every part is forged to your drawing, or to a machining envelope agreed at enquiry. There is no standard catalogue. Send a dimension, a weight or a print and we quote against it.
| Forged form | Typical size range | Common use |
|---|---|---|
| Seamless rolled rings | OD 200 to 3,000 mm, height to 800 mm | Vessel shell rings, furnace retort rings |
| Forged flanges | To ASME B16.5, B16.47, EN 1092-1 or drawing | Piping and vessel connections |
| Forged discs and blanks | OD to 2,500 mm, thickness to 600 mm | Covers, blind flanges, machining blanks |
| Forged round bars | Ø 60 to 800 mm, length to 6,000 mm | Stock for machined components |
| Forged shafts and spindles | Ø to 800 mm, length to 6,000 mm | Agitators, pumps, rotating equipment |
| Forged sleeves and bushings | OD to 1,200 mm, hollow forged | Wear parts, bearing housings |
| Forged tube sheets | OD to 2,500 mm | Shell and tube heat exchangers |
| Forged blocks and plates | To drawing | Valve bodies, manifolds, die blanks |
| Forged tubes and hollow bars | Bored or trepanned to drawing | Pressure parts, nozzles |
How we forge Z8NC33-21
- MeltingElectric arc furnace with AOD or VOD refining. We add electroslag remelting where the drawing or the end use calls for a cleaner, more uniform ingot.
- Ingot and billet preparationIngots are conditioned and cropped. Chemistry is checked before the first forging heat.
- Open die forgingUpsetting, drawing out and punching on hydraulic presses. Reduction ratio and finishing temperature are controlled so the flow lines follow the shape of the part.
- Ring rollingPunched blanks go to the ring mill and are expanded into seamless rolled rings with continuous circumferential grain.
- Solution annealingHeating to about 1,150 °C and rapid cooling, in furnaces with calibrated and recorded charts.
- Rough machiningTurning and boring to the agreed envelope, so that ultrasonic testing runs on a properly prepared surface.
- Testing and inspectionChemistry, mechanical tests, grain size, ultrasonic examination and dimensional check before release.
- Documentation and despatchCertificates issued, marking applied, part packed for sea or air freight.
Testing, inspection and certificates
Non destructive testing
- Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, at the quality class you nominate
- Liquid penetrant testing to ASTM E165 where surface indications matter
- Positive material identification by portable spectrometer
Destructive and metallurgical testing
- Tensile and yield testing at room temperature, and at elevated temperature on request
- Impact testing where the specification requires it
- Grain size to ASTM E112
- Intergranular corrosion testing on request
Documentation
Forgings come with an EN 10204 3.1 mill certificate as standard. Where the order calls for it we arrange EN 10204 3.2 certification with witness by a third party inspection body, and we work to a customer inspection and test plan with defined hold and witness points.
Where Z8NC33-21 forgings are used
Petrochemical and refining
- Reformer and cracking furnace hardware
- Forged headers, nozzles and manifolds
- Hydrocracker and hydrotreater internals
Heat treatment and furnaces
- Retorts, muffles and radiant tube components
- Furnace fixtures, grids and support rings
Pressure vessels and heat exchangers
- Forged tube sheets and shell rings
- Flanges, nozzles and blind covers
- Columns, towers and process modules
Power generation
- Superheater and steam header components
- Steam generator forgings
Valves and flow control
- Valve bodies, bonnets and seat rings
- Valve stems and forged blocks
Rotating and process equipment
- Agitator and pump shafts
- Sleeves, bushings and wear rings
- Crystalliser and mixer parts
Frequently asked questions about Z8NC33-21
What is Z8NC33-21?
Z8NC33-21 is the French AFNOR name for an austenitic nickel iron chromium heat resistant alloy with about 33% nickel and 21% chromium, the balance iron, plus controlled aluminium and titanium. It is used where a part has to resist oxidation, carburisation and creep at high temperature, usually above 600 °C.
What is Z8NC33-21 equivalent to?
Z8NC33-21 matches Alloy 800H, sold under the trade name Incoloy® 800H. Its cross references are UNS N08810, W.Nr. 1.4958, EN steel name X5NiCrAlTi31-20, BS NA 15(H), JIS NCF 800H and GOST ХН32Т.
What is the chemical composition of Z8NC33-21?
Carbon 0.06 to 0.10%, silicon 1.00% max, manganese 1.50% max, sulphur 0.015% max, nickel 30.0 to 35.0%, chromium 19.0 to 23.0%, copper 0.75% max, aluminium 0.15 to 0.60%, titanium 0.15 to 0.60%, iron 39.5% minimum as the balance. All values are weight percent.
Is Z8NC33-21 the same as Alloy 800 or Alloy 800HT?
No. All three share the same iron nickel chromium base but differ in carbon, grain size and the combined aluminium and titanium content. Z8NC33-21 matches Alloy 800H (N08810). Alloy 800 (N08800) has lower carbon and is normally kept below about 650 °C. Alloy 800HT (N08811) has tighter aluminium and titanium minimums for higher creep rupture strength.
What forged shapes can be made in Z8NC33-21?
Seamless rolled rings, forged flanges, discs and blanks, round bars, shafts and spindles, sleeves, bushings, hollow bars, tube sheets and forged blocks. All are made to customer drawing rather than from a standard catalogue.
What heat treatment is applied to Z8NC33-21 forgings?
Solution annealing at about 1,150 °C followed by rapid cooling. Where a drawing calls for it, solution treatment and ageing can be run in sequence. Furnace charts are recorded and supplied with the certificate.
What non destructive testing is carried out?
Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, at the quality class named on the order. Liquid penetrant testing and positive material identification are available where the specification calls for them.
What certificates are supplied with Z8NC33-21 forgings?
An EN 10204 3.1 mill certificate is supplied as standard. EN 10204 3.2 certification with third party witness is available on request, as is work to a customer inspection and test plan.
Who manufactures Z8NC33-21 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. It makes Z8NC33-21 forged rings, flanges, discs, shafts and tube sheets to customer drawing. Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659.
What information do you need to quote a Z8NC33-21 forging?
A drawing or sketch with dimensions and tolerances, the quantity, the governing specification, the certificate level, any ultrasonic testing class, and the delivery condition, meaning as forged, rough machined or finish machined. If the drawing is not ready, outside diameter, inside diameter, height or length and the finished weight are enough for a budget price.
Request a quotation for Z8NC33-21 forgings
Send the drawing and the quantity. You get a price, a weight and a delivery date back, normally within one working day.
- Drawing, sketch or the finished dimensions
- Quantity and the governing specification
- Certificate level and any ultrasonic testing class
- As forged, rough machined or finish machined