MIL-S-81591 (NOTICE 1), MILITARY SPECIFICATION: STEEL, INVESTMENT CASTINGS, CARBON AND CORROSION RESISTING (23 FEB 1993) [S/S BY VARIOUS NON-GOVERNMENT STANDARDS - REFER TO NOTICE 1]., MIL-S-81591 is inactive for new design. New designs should use the following non-governmental standards as shown below.