MIL-S-24451A, MILITARY SPECIFICATION: STEEL HEAT TREATED HEADS, ALLOY STRUCTURAL, HIGH YIELD STRENGTH (HY-80 AND HY-100) (31-JUL-1990) [SEE NOTICE 1 FOR REPLACEMENT INFORMATION]

MIL-S-24451A, MILITARY SPECIFICATION: STEEL HEAT TREATED HEADS, ALLOY STRUCTURAL, HIGH YIELD STRENGTH (HY-80 AND HY-100) (31-JUL-1990) [SEE NOTICE 1 FOR REPLACEMENT INFORMATION]., This specification covers HY-80 and HY-1000 heat treated heads. The requirements for HY-80 apply to thickness to 8 inches inclusive, and HY-100 to thickness up to 3 inches inclusive. Two piece heads consist of heads made from two flat plates welded together and then formed as one piece.