The 800 series alloys were developed during the 1950s. At that time, nickel was in high demand for national defense. In order to create a heat-resistant and corrosion-resistant material for commercial use with a lower nickel content, the 800 series alloys were created.
Alloy 800 has 2 notable variations. Alloy 800H (UNS N08810) restricts the carbon content to the higher end of the acceptable range of Alloy 800. Alloy 800 HT (UNS N08811) restricts the carbon, aluminum and titanium contents all to the high end. The advantage of the restricted chemistry results in higher creep strength and stress rupture properties. In our experience, most material purchased as Alloy 800 also qualifies as Alloy 800H and Alloy 800HT.
Environments where Alloy 800 fasteners have been used range from cryogenic to 1500º F (800º C). Alloy 800H and 800HT increase this range. Alloy 800 is particularly resistant to nitric acid and is used in the chemical and petrochemical industries.