Medium-carbon steels are similar to low-carbon steels except that the carbon ranges from 0.30 to 0.60 %and the manganese from 0.60 to 1.65%. Increasing the carbon content to approximately 0.5% with an accompanying increase in manganese allows medium carbon steels to be used in the quenched and tempered condition. The uses of medium carbon-manganese steels include shafts, axles, gears, crankshafts, couplings and forgings. Steels in the 0.40 to 0.60% carbon range are also used for rails, railway wheels and rail axles.
* Some key points provided by www.key-to-steel.com.