AMS 6304 is a specification of Steel 17-22A, which is ultra-high-strength low alloy steel with a high percentage of Carbon, Molybdenum, Vanadium, and Chromium. Its main characteristics are excellent high-temperature strength and high heat resistance.
This Steel 17-22A specification is mainly used for manufacturing of parts that require high heat resistance in the aircraft industry.
AMS 6304 is available as bar, forging and tubing, and is characterized by 1000-hour rupture strength of temperatures up to 1100°F (593°C) or 30,000 psi.
There are three recommended heat treatments for AMS 6304. Normalizing is done at a temperature of 1700-1850°F (926-1010°C). Hold at that temperature for each inch of thickness. Then the part should be air cooled or fan cooled if the process is to be accelerated. Please note that all surfaces of the part must have access to air for even cooling.
After normalizing, annealing is done at 1450°F (787°C) for one hour per inch of thickness to get to 1100°F (593°C). Additional hardening can be achieved by oil quenching at a temperature of 1750°F (955°C).
The AMS 6304 specification can be welded using all popular welding processes. The use of a welding rod with the 17-22A(S) is recommended, due to its higher concentration of carbon and chromium.