Incoloy800H/800HT

Incoloyÿ¡§ alloys 800H and 800HTÿ¡§ have significantly higher creep and rupture strength than Incoloyÿ¡§ 800.?The three alloys have nearly identical chemical composition limits.?However, the chemical composition limits vary with carbon, aluminum and titanium.?The carbon content of Incoloyÿ¡§ alloy 800 (UNS n08800) is 0.10% max with no limit on the lower end.?The carbon content for Incoloyÿ¡§ alloy 800H (UNS N08810) is 0.05% to 0.10% which is the upper end of the 0.10% maximum specified for Incoloyÿ¡§ alloy 800.?The chemical limits for Incoloyÿ¡§ 800HTÿ¡§ (UNS08811) are even more restrictive yet still within the limits specified for Incoloyÿ¡§ 800H.?The carbon content for Incoloyÿ¡§ alloy 800HTÿ¡§ is further restricted to 0.06%-0.10%.?Additionally the Al plus Ti content of Incoloyÿ¡§ alloy 800HTÿ¡§ is restricted to 0.85%-1.20%.?Note that the chemical composition for Incoloyÿ¡§ alloy 800HTÿ¡§ will always be within the limits of Incoloyÿ¡§ alloy 800H.?Note also that the limits for Incoloyÿ¡§ alloy 800H may or may not be within the limits of Incoloyÿ¡§ alloy 800HTÿ¡§.  
In addition to the controlled carbon content, Incoloyÿ¡§ alloys 800H and 800HTÿ¡§ receive a high temperature annealing treatment that produces an average grain size of ASTM 5 or coarser.?The annealing treatment and restricted chemical composition are responsible for these alloys having greater creep and rupture strength.  
The mechanical properties of Incoloyÿ¡§ alloys 800H and 800HTÿ¡§, combined with their resistance to high temperature corrosion, make these alloys exceptionally useful for many applications involving long-term exposure to elevated temperatures and corrosive atmospheres.?In the hydrocarbon processing industry, these alloys are used in steam/hydrocarbon reforming for catalyst tubing convection tubing, pigtails, outlet manifolds, and quenching-system piping; in ethylene production for both convection and cracking tubes, and pigtails; in oxy-alcohol production for tubing in hydrogenation heaters; in hydrodealkylation units for heater tubing; and i the production of vinyl chloride monomer for cracking tubes, return bends and inlet and outlet flanges.
Industrial heating is another area of wide usage for both Incoloyÿ¡§ 800H and 800HTÿ¡§.?In various types of heat treating furnaces, these alloys are used for radiant tubes, muffles, retorts, and assorted furnace fixtures.
Alloys 800H and 800HTÿ¡§ are also used in power generation for steam superheating tubing and high temperature heat exchangers in gas cooled nuclear reactors.