800H/AT is an austenitic heat resistant alloy designed for high temperature structural applications. The strength of 800H/AT is achieved by controlled levels of carbon, aluminum and titanium along with a 2100°F minimum anneal to achieve a grain size of ASTM 5 or coarser.

800H/AT is commonly welded using RA 82 (ERNiCr-3) bare wire for applications under 1450°F. RA330-04 (N08334) bare wire offers a closer match of thermal expansion coefficient, and somewhat higher strength. For maximum strength alloy 617 (ERNiCrCoMo-1) bare wire or 117 (ENiCrCoMo-1) covered electrodes are suggested. To avoid possible stress relaxation grain boundary cracking of N08811 in applications above 1000°F the welded fabrication may be heated 1650°F for about one hour per inch of thickness or 30 minutes minimum then air cooled.