Alloy 800/800H/AT, a nickel-iron-chromium alloy, is renowned for its suitability in high-temperature critical applications. This austenitic heat-resistant alloy is designed to withstand extreme temperatures, with Alloy 800/800H/AT achieving its strength through controlled levels of carbon, aluminum, and titanium, along with a minimum annealing temperature of 1148°C to achieve a grain size of ASTM 5 or coarser. With precise control over its composition and heat treatment, Alloy 800/800H/AT exhibits significantly higher stress rupture strength compared to Alloy 800, making it ideal for demanding environments.

Incoloy 800 is commonly used in various industries, including petrochemical, chemical processing, and power generation, where high-temperature resistance is paramount. Welding of this alloy is typically performed using RA82 (ERNiCr-3) bare wire for applications below 788°C. Alternatively, RA330-04 (UNS N08334) filler wire offers a closer match in terms of thermal expansion coefficient and higher strength. For maximum strength, Alloy 617 (ERNiCrCoMo-1) bare wire or 117 (ENiCrCoMo-1) coated electrodes are recommended. To mitigate potential stress relaxation and grain boundary cracking in applications above 538°C, the welded structure may undergo heat treatment at 899°C for a duration proportional to its thickness or a minimum of 30 minutes, followed by air cooling.