Mechanical Properties of 4340 Steel Subjected to Short-Time Tempering within the Tempered Martensite Embrittlement Regime

The influence of short-time tempering on mechanical properties of 4340 steel within the tempered martensite embrittlement (TME) regime was examined. The Hollomon-Jaffe tempering parameter was used to develop tempering treatments to compare short-time and conventional tempering conditions at an equivalent hardness. This work confirms the applicability of the Hollomon-Jaffe tempering parameter in predicting equivalent hardness values for various time-temperature combinations. However, variation in toughness and strength was observed at equivalent hardness values; therefore, calling into question the use of hardness as a universal metric to describe time temperature equivalency. Mechanical property results indicate the promising nature of short-time tempering for improved toughness within the TME regime.