Annealing Characteristics of Oxygen Free Copper Sheet Processed by Differential Speed Rolling

Annealing characteristics of an oxygen free copper (OFC) processed by differential speed rolling (DSR) were investigated in detail. An OFC sample with a thickness of 1mm was rolled to 35% reduction at ambient temperature without lubrication, varying the differential speed ratio from 1.0:1 to 2.2:1, and then annealed for 0.5h at various temperatures from 100 to 400 degrees C. Different recrystallization behavior was observed depending on the differential speed ratio, especially in the case of annealing at 200 degrees C Complete recrystallization occurred in the specimens annealed at temperatures above 250 degrees C regardless of the differential ratios. The hardness distribution in the thickness direction of the rolled OFC sheets varied depending on the differential speed ratios. These annealing characteristics were explained by the magnitude of shear strain introduced during rolling.