ncoloy 800 is primarily used in applications with temperatures up to 1100° F,  where alloys 800H and 800HT are normally used in temperatures above 1100° F  where resistance to creep and rupture is required. The chemical balance allows  the nickel steel alloy to exhibit excellent resistance to carburization,  oxidation and nitriding atmospheres. Incoloy 800HT will not become embrittled  even after long periods of usage in the 1200-1600° F range where many stainless  steels become brittle. Excellent cold forming characteristics typically  associated with the nickel-chromium alloys are exhibited with 800HT. When cold  formed extensively the grain size produces a visibly undulated surface called  “orange peel”. Incoloy 800HT can be welded by the common techniques used on  stainless steels.

What are the characteristics of Incoloy 800H/HT?

· High temperature strength

· High creep rupture strength

· Resistant to oxidation and carburization in high temperature  environments

· Good corrosion resistance in many acidic environments

· Good resistance to many sulfur-containing atmospheres

Alloy 800 (UNS N08800) Chemical Composition, %

Alloy 800H (UNS N08810) Chemical Composition, %

Alloy 800HT (UNS N08811) Chemical Composition, %

*Note that the chemical composition of Incoloy 800HT will always be within  the limits of Incoloy 800H.

*Note the limits of Incoloy 800H may or may not be within the limits of  Incoloy 800HT.

In what applications is Incoloy 800H/HT used?

· Ethylene furnace quench boilers

· Hydrocarbon cracking

· Valves, fittings and other components exposed to corrosive attack from  1100-1800° F

· Industrial furnaces

· Heat-treating equipment

· Chemical and petrochemical processing

· Super-heater and re-heaters in power plants

· Pressure vessels

· Heat exchangers

Alloys 800H/HT are used in a variety of applications involving exposure to  corrosive environments and high temperatures such as heat treating equipment,  chemical and petrochemical processing, nuclear power plants and the paper pulp  industry. Heat-treating equipment such as baskets, trays, and fixtures employ  Incoloy 800H/HT. Chemical and petrochemical processing industries use the alloys  for heat exchangers and other piping systems in nitric acid media especially  where resistance to chloride stress-corrosion cracking is required. Power plants  use them for super-heater and re-heater tubing.

For information on machining, click here.

ASTM Specifications

Mechanical Properties

Typical room temperature Tensile Properties of Annealed Material