Precipitation Hardening Behavior of V and/or Cu Bearing Middle Carbon Steels

In this study, the precipitation hardening behavior of middle carbon steels with single and multiple additions of 0.3mass%V and 2mass%Cu has been investigated. The precipitation treatment was carried out isothermally at 550ºC, 600ºC and 650ºC. In the 0.3mass%V bearing steel, precipitation hardening was observed at 600ºC and 650ºC while no significant increase in hardness was observed at 550ºC. When 2mass% Cu was added to the 0.3mass%V bearing steel, the hardness attributed to the precipitation hardening of Cu was added to that attributed to the precipitation hardening of VC in the cases of 600ºC and 650ºC. In the case of 550ºC, the V addition into the Cu bearing steel markedly increased the hardness although the precipitation hardening of VC was hardly observed in the 0.3mass%V bearing steel. In the paper, the different precipitation hardening behavior of the three steels is discussed in detail in consideration of the observed precipitation behavior.