Improved hardenability or low-alloy machine grade steel; in annealed condition it can be subjected to hardening by quenching and tempering to hardness values ¿¿around 50 HRC (see general recommendations for heat treatment), in pre-tempered condition (treated or tempered), it has a very good combination between toughness and resistance that Allows direct use in machine part applications, higher surface-to-core hardness uniformity, higher resistance to mechanical fatigue than 4140 steel.