INCOLOY® Alloy 800H/800HT UNS N08810/UNS N08811

Incoloy 800, 800H, and 800HT are nickel-iron-chromium alloys with good  strength and excellent resistance to oxidation and carburization in  high-temperature exposure. These nickel steel alloys are identical except for  the higher level of carbon in alloy 800H, and the addition of up to 1.20 percent  aluminum and titanium in alloy 800HT. Incoloy 800 was the first of these alloys  and it was slightly modified into Incoloy 800H. This modification was to control  carbon (.05-.10%) and grain size to optimize stress rupture properties. Incoloy  800HT has further modifications to the combined titanium and aluminum levels  (.85-1.20%) to ensure optimum high temperature properties. The nickel alloy is  dual certified (800H/HT) and combines the properties of both forms. Incoloy  800H/HT alloy was intended for high temperature structural applications. The  nickel content makes the alloys highly resistant to both chloride  stress-corrosion cracking and to embrittlement from precipitation of sigma  phase. The general corrosion resistance is excellent. In the solution annealed  condition, alloys 800H and 800HT have superior creep and stress rupture  properties. Today, most suppliers, including Mega Mex, only carry the dual  certified 800H/HT alloy.

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.

Alloy 800 (UNS N08800) Chemical Composition, %

Alloy 800H (UNS N08810) Chemical Composition, %

Alloy 800HT (UNS N08811) Chemical Composition, %