What Is The Difference Between Inconel 800 And 800H?

What is the difference between Inconel 800 and 800H?

Incoloy 800, 800H and 800HT are nickel-iron-chromium alloys with good strength and excellent resistance to oxidation and carburization at elevated temperatures. These nickel-steel alloys are identical except that the carbon content is higher in the 800H alloy and up to 1.20% aluminum and titanium are added to the 800HT alloy. Incoloy 800 was the first of these alloys and was slightly modified to become Incoloy 800H. This modification was to control the carbon (0.05-0.10%) and grain size to optimize stress rupture properties. Incoloy 800HT was further modified to control the combined content of titanium and aluminum (0.85-1.20%) to ensure optimal elevated temperature properties. The nickel alloys are dual certified (800H/HT) and combine the properties of both forms. The Incoloy 800H/HT alloy is suitable for high temperature structural applications. The nickel content gives the alloy a strong resistance to chloride stress corrosion cracking and sigma precipitation embrittlement. Overall corrosion resistance is excellent. In the solution annealed condition, the 800H and 800HT alloys have excellent creep and stress rupture properties. Today, most suppliers, including Mega Mex, offer only dual-certified 800H/HT alloys.

Incoloy 800 is primarily used in applications up to 1100° F, while the 800H and 800HT alloys are typically used above 1100° F where creep and rupture resistance is required. The chemical balance allows the nickel-steel alloy to exhibit excellent resistance to carburizing, oxidizing, and nitriding environments. Even after extended use in the 1200-1600° F range, Incoloy 800HT does not become brittle, as many stainless steels do at these temperatures. 800HT has the excellent cold forming characteristics typical of nickel-chromium alloys. When cold forming large areas, the grain size produces a noticeable undulating surface known as "orange peel." Incoloy 800HT can be welded using the same welding techniques commonly used for stainless steels.

In what forms does Gnee Steel offer Incoloy 800H/HT?
Plates
Bars
Tubes (welded and seamless)
Fittings
Elbows, tees, stub ends, return pipes, caps, crossheads, reducers, pipe fittings, etc.
Wire
What are the characteristics of Incoloy 800H/HT?
High temperature strength
High creep rupture strength
Resistance to oxidation and carburization at high temperatures
Good corrosion resistance in many sour 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, %