Incoloy 800H: Complete Properties & Application Guide

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Overview

Incoloy 800H (UNS N08810 / W.Nr. 1.4958) is a controlled-carbon version of Incoloy 800 with improved creep and rupture properties at elevated temperatures. The higher carbon content (0.05-0.10%) provides better high-temperature strength through carbide precipitation strengthening.

Chemical Composition

The chemical composition of Incoloy 800H is carefully controlled to achieve its unique combination of properties and performance characteristics.

Element	Min %	Max %
Nickel (Ni)	30.0	35.0
Iron (Fe)	39.5	Balance
Chromium (Cr)	19.0	23.0
Carbon (C)	0.05	0.10
Aluminum (Al)	0.15	0.60
Titanium (Ti)	0.15	0.60
Manganese (Mn)	—	1.5
Silicon (Si)	—	1.0

Mechanical Properties at Room Temperature

The mechanical properties of Incoloy 800H vary depending on product form and heat treatment condition. The data below represents typical values for solution-annealed material.

Property	Value
Tensile Strength	450 MPa
Yield Strength (0.2% offset)	170 MPa
Elongation in 2 inches	50%
Density	7.94 g/cm3
Melting Point	1385 °C
Max Service Temperature	980 °C

Corrosion Resistance

Excellent resistance to oxidation, carburization, and sulfidation at elevated temperatures. Good resistance to steam and steam-air mixtures. The alloy performs well in high-temperature hydrogen environments, making it suitable for petrochemical applications.

Applications

The unique combination of properties makes Incoloy 800H suitable for a wide range of demanding applications:

• Steam Generation: Superheater and reheater tubing in power boilers.
• Hydrocarbon Processing: Catalyst tubing and furnace tubes in refineries.
• Chemical Processing: High-temperature reaction vessels and heat exchangers.
• Nuclear Power: Steam generator tubing and heat exchanger components.
• Heat Treatment: Muffles and furnace components for continuous operation.

Available Product Forms

Hangbo Alloy Group manufactures and supplies Incoloy 800H in the following product forms, conforming to ASTM, AMS, and ASME specifications:

• Round Bars: Diameters from 6 mm to 300 mm, hot-finished or cold-drawn, solution annealed.
• Seamless Tubes & Pipes: Sizes from 6 mm OD to 219 mm OD, various wall thicknesses.
• Plates & Sheets: Thicknesses from 0.5 mm to 50 mm, hot-rolled or cold-rolled.
• Forgings: Custom flanges, rings, discs, and complex shapes per customer drawing.
• Welding Wire: Diameters 0.8 mm to 5.0 mm, precision-wound coils and spools.

Related Standards

Standard	Description
ASTM B407	Seamless Pipe and Tube
ASTM B409	Plate, Sheet, and Strip
ASTM B408	Bar and Rod
ASTM B564	Forgings
ASME SB-407	Pressure Vessel Code
ASTM B366	Fittings

Creep and Stress-Rupture Performance

The "H" in 800H denotes a controlled carbon content (0.05–0.10 %) plus a grain size requirement — deliberately engineered for creep-limited service rather than room-temperature strength.

Temperature	Stress for 100 000 h rupture
600 °C	≈ 130 MPa
700 °C	≈ 60 MPa
800 °C	≈ 28 MPa
900 °C	≈ 12 MPa
Design ceiling (oxidation)	≈ 1100 °C

Values are typical for solution-annealed 800H; always design against the applicable code allowable rather than average data. More background is in our article on creep and stress rupture.

Fabrication, Welding and Heat Treatment

• Solution anneal at 1120–1175 °C with rapid cooling — this sets the coarse grain structure the grade relies on.
• Hot work between 1200 °C and 950 °C; do not work below 950 °C.
• Weld with ERNiCr-3 (Inconel 82) or ERNiCrFe-2 for dissimilar joints and high-temperature service.
• No preheat needed on thin sections; 150 °C for heavy sections. Keep interpass below 150 °C.
• 800H resists carburisation far better than austenitic stainless, but avoid prolonged exposure in strongly reducing sulphur atmospheres.

Frequently Asked Questions

What is the difference between Incoloy 800, 800H and 800HT?

All share the same basic Ni-Fe-Cr chemistry. 800H adds a controlled carbon range and grain-size requirement for creep strength; 800HT further restricts Al+Ti and is annealed for optimum high-temperature rupture properties.

Can 800H be used in carburising atmospheres?

Yes — it is a standard choice for pyrolysis and reformer furnace tubing precisely because its oxide scale resists carbon ingress. For severe carburising duty, consider a higher-nickel grade or an aluminised surface.

Does 800H need post-weld heat treatment?

Not generally. Stress relief at 900 °C is used only for thick sections or where the component must retain dimensional stability in service.

What is the chemical composition of Incoloy 800H?

UNS N08810 / W.Nr. 1.4958: 30-35% nickel, 19-23% chromium, iron balance, with controlled carbon 0.05-0.10% and Al+Ti additions for carbide strengthening.

How does 800H differ from Incoloy 800?

800H has controlled carbon and a coarser annealed grain size, giving improved creep and stress-rupture strength at elevated temperature over the base 800 grade.

What are its mechanical properties?

Tensile about 450 MPa, yield about 170 MPa and 50% elongation at room temperature; elevated-temperature strength is creep-limited rather than tensile-limited.

What is the maximum service temperature?

About 980 °C for oxidation resistance, with long-term creep applications typically kept around 593 °C unless upgraded to 800HT.

What applications suit 800H?

Ethylene and petrochemical furnace tubes, heat-treating equipment, and steam/hydrocarbon processing where creep and carburization resistance matter.

What standards cover 800H?

UNS N08810 / W.Nr. 1.4958, with ASTM B163/B407/B408 covering tube, pipe and plate, plus the usual ASME boiler and pressure-vessel sections.

Contact Us for Incoloy 800H

Hangbo Alloy Group maintains extensive inventory of Incoloy 800H in all standard product forms. We can provide mill test certificates, third-party inspection reports (SGS, TUV), and custom processing services.

For quotations, material certifications, or technical consultation, contact our sales team or call +86 166 2109 2936. We typically respond within 10 minutes.