• HS 220-18 is a low carbon, high silicon, chromium nickel molybdenum alloy steel. It was one of the first grades developed in the high strength class, combining strength with toughness and ductility. It has relatively high impact resistance because of its low notch sensitivity at the high hardness at which this alloy is commonly used. It is available as a basic electric furnace air melt and vacuum degassed product to meet the high aircraft quality standards of AMS 2301. In addition, thismore