ALLOY 800 • UNS N08800 • WNR 1.4876
Alloy 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/HT and the addition of up to 1.20 percent aluminium and titanium in alloy 800HT. 800 was the first of these alloys and it was slightly modified into 800H. This modification was to control carbon (.05-.10%) and grain size to optimize stress rupture properties. In heat treatment applications 800HT has further modifications to the combined titanium and aluminium levels (.85-1.20%) to ensure optimum high temperature properties. Alloy 800H/HT was intended for high temperature structural applications. The nickel content makes the alloys highly resistant to both carborisation and to embrittlement from precipitation of sigma phase.