An analysis of combined cyclic heat treatment performance

The strengthening of AISI 4140 steel by cyclic heat treatment has been investigated. The applied cyclic heat treatment was consisted of both, temperature cycling with diffusional transformation and double quenching with diffusionless transformation. Both, temperature cycling and second quenching increase yield strength and Charpy-V toughness as measures of steel strength and toughness. The increase of yield strength and Charpy-V notch toughness are directly in relation of structure fineness. Much better mechanical properties are obtained by the appropriate cyclic heat treatment than by the quenching and tempering of steel AISI 4140.