Hardening of Cu/Carbon Steel Multilayered Sheet by Quenching

A Cu/carbon steel multilayered sheet was quenched, and its tensile properties and electrical conductivity were evaluated. A full martensite structure was developed in the carbon steel layers in the multilayered sheet after quenching at 1063 K. The obtained Cu/martensite steel multilayered sheet exhibited a much higher ultimate tensile stress and approximately identical electrical conductivity compared to those in the Cu/carbon steel multilayered sheet without a quenching process. The decrease in the electrical conductivity during the quenching process in the multilayered sheet can be predicted from the decrease in the conductivity of the Cu layers owing to the diffusion of Fe atoms into the Cu layer. The ultimate tensile stress-electrical conductivity balance in the Cu/martensite steel multilayered sheet was 5.0 × 104 MPa%IACS, which is higher than that in conventional commercial Cu alloys. The ultimate tensile stress-total strain balance in the Cu/martensite steel multilayered sheet was significantly lower than that in each phase in the sheet. The measured ultimate tensile stress and electrical conductivity in the Cu/martensite steel multilayered sheet were approximately identical to the values estimated from the rule of mixture, using the tensile stress, electrical conductivity, and volume fraction of each component phase. This result indicates that the ultimate tensile stress and electrical conductivity of multilayered sheets can be easily controlled based on the rule of mixture.