AS U21 – 75 ton, 2 1/2 per cent nickel-chromium-molybdenum steel (high-carbon) (limiting ruling section 6 in.)
This specifications applies to bars and billets for forging, black or bright bars for machining, forgings other than those for crank and propeller shafts, forgings for crank and propeller shafts, and finished heat-treated machined parts.
