Alloy 800H are two individual solid solution strengthened, iron-nickel-chromium alloys. They are typically offered as one, dual certified alloy, meeting the chemical composition requirements of both alloys. The principle difference between alloys 800H and 800HT® is the restricted aluminum and titanium content in 800HT®, which results in higher creep and stress rupture properties. Both alloy 800H and 800HT® are generally considered to be superior to the base alloy 800 (UNS N08800) because of greater creep and stress rupture properties and a more restrictive C wt% range. Alloy 800H limits the C wt% from just 0.1% max in base alloy 800 to a 0.5% to 0.1% range. Alloy 800HT® further controls this by limiting the C wt% to 0.6% to 0.1%. There are also limitations on the grain size for alloy 800 H/HT® that are not in place for alloy 800.
