Nickel-Iron-Chromium Alloy / UNS N08810 / ASTM B564

UNS N08810 Forgings (Alloy 800H): Rolled Rings, Flanges, Bars, Discs and Shafts

What UNS N08810 (Alloy 800H) is

UNS N08810 is a solid-solution-strengthened nickel-iron-chromium alloy. The nominal 32 % nickel content makes it highly resistant to chloride stress-corrosion cracking and to embrittlement from sigma-phase precipitation. Chromium at 19–23 % provides the oxidation resistance, and the aluminium and titanium additions help stabilise the surface oxide in carburising atmospheres.

It is the high-temperature version of Alloy 800 (UNS N08800). On a chemical analysis the two grades look almost identical, but N08810 carries a controlled carbon range of 0.05–0.10 % and a minimum grain size of ASTM 5 or coarser. Those requirements are what produce the creep and stress-rupture strength above 600 °C. A fine-grained forging can pass N08800 chemistry and still fall short in N08810 service, so we check grain size on every heat.

Alloy 800H keeps useful ductility below about 700 °C (1290 °F) and shows good creep-rupture behaviour above 600 °C (1100 °F). It is approved for construction under ASME Boiler and Pressure Vessel Code Sections I, III and VIII, and Section VIII Division 1 assigns it maximum allowable stresses up to 1500 °F (816 °C). Very few code-listed alloys reach that temperature.

Alloy 800 vs 800H vs 800HT

A good share of the enquiries we get for “Incoloy 800” turn out to describe service conditions that need 800H or 800HT. It is worth settling this before the drawing goes out.

Material that satisfies both sets of limits can be dual-certified to N08810 and N08811. Where the design code or end user allows it, ask for dual certification at the enquiry stage. It protects the order against a later specification change and costs nothing extra.

Chemical composition of UNS N08810

Iron is the balance element and is reported to a 39.5 % minimum rather than a range. Confirm limits against the current revision of ASTM B564 for the applicable product form, together with any client or end-user supplementary requirements.

Mechanical properties of UNS N08810 forgings

Typical values are indicative results from solution-annealed open-die forgings and are not guaranteed minima. The certified values on the mill test certificate govern. Elevated-temperature tensile testing at the design temperature can be added to any order.

Above roughly 600 °C the design case is no longer short-term tensile strength but creep and stress rupture. That is why the H grade exists, and why the solution-anneal temperature and the resulting grain size are treated as critical process parameters in our shop rather than as routine heat treatment.

Physical properties

Typical published values for wrought Alloy 800H, given for preliminary design. Confirm against the applicable design code before use.

Equivalent and cross-referenced designations

Cross-references are a purchasing aid. They are close equivalents rather than exact substitutions, so confirm acceptance with the design authority before substituting a grade.

Melting practice, forging and heat treatment

We control UNS N08810 from the melt route onward. On a creep-governed alloy, correct chemistry on its own will not deliver a working part.

• Melting. EAF with AOD or VOD refining, and ESR remelting where the specification, section size or end user calls for improved cleanliness and lower segregation.
• Ingot to forging. Upsetting and drawing on hydraulic open-die presses to a minimum 3:1 forging reduction ratio from ingot, with higher ratios available for critical sections.
• Forging temperature. Worked from about 1180 °C down to a 980 °C finishing temperature, with reheats scheduled to keep the whole section in range.
• Ring rolling. Seamless rolled rings produced on a radial-axial ring mill, giving continuous circumferential grain flow instead of the interrupted flow of a cut-and-welded ring.
• Solution anneal. Typically 1120 to 1180 °C (2050 to 2150 °F), held and rapidly cooled, in furnaces with calibrated thermocouples and recorded charts.
• Grain size check. ASTM E112 on every heat, confirming ASTM 5 or coarser before release.

UNS N08810 forging capability

Ranges are for guidance. Send the drawing and we will confirm feasibility, the machining allowance and the ingot size against the exact geometry.

UNS N08810 forged forms we supply

All forms are available as-forged, rough machined to a set allowance, or finish machined to print. On critical parts we usually suggest rough machining before ultrasonic examination, since a cleaner surface gives a more reliable UT result.

Where UNS N08810 forgings are used

Testing, inspection and certification

Intergranular corrosion testing, macro-etch, impact testing and heat-treatment chart submission can be added as supplementary requirements at the enquiry stage. Every forging is stamped and traceable to its heat number and to the mill test certificate.

How to request a UNS N08810 quotation

Send the following to sales@steelforgepieces.com and we will normally return a price and lead time within 24 hours:

1. Drawing (PDF, DWG or STEP) or the finished dimensions, plus the machining allowance if you have one in mind
2. Grade and specification, for example UNS N08810 to ASTM B564, or dual N08810 and N08811
3. Delivery condition: as-forged, rough machined or finish machined
4. Quantity, and whether this is a prototype, a repeat order or a framework contract
5. Certificate level, EN 10204 3.1 or 3.2, and the nominated third party if 3.2
6. NDT requirements and acceptance class, plus any ASME code or end-user specification
7. Destination port and required delivery date

Frequently asked questions about UNS N08810

Related nickel alloy forging grades

If UNS N08810 is not the right fit for your service conditions, these grades from our nickel alloy range are the usual alternatives:

About the supplier

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We forge rings, seamless rolled rings, flanges, bars, discs, sleeves, tube sheets, shafts and custom open-die shapes in carbon steel, alloy steel, tool steel, stainless steel and nickel-based alloys, and ship to customers across Europe, North America, the Middle East and Asia.

Drawings go straight to our engineers. Send yours to sales@steelforgepieces.com or call +86 189 2135 9659.