Enhancement of mechanical properties of bulk copper processed by room temperature rolling and cryorolling

Abstract

Objectives: In the present work, we have examined and reported the mechanical and microstructures properties of bulk Cu subjected to Room Temperature Rolling (RTR) and Cryorolling (CR) in Liquid Nitrogen temperature (LN2). Samples deformed plastically to obtain 90% Reduction in Area (RA). Methods/Statistical analysis: The mechanical properties of samples at room temperature rolling and cryorolled samples investigated by tensile testing and hardness measurement. Brittle type of fracture was identified for 90% RA cryorolled samples from fractography analysis, whereas the presence of the small dimples in the fractured surfaces of Room Temperature Rolled (RTR) tensile specimens shows a ductile failure. Findings: The increase in tensile strength is due to the refinement of the grains due to collective effect of inhibition of dynamic recovery and the recrystallization processes, an increase of the high density dislocations in the cryorolling. The grain size refinement has been confirmed by TEM analysis. Application/Improvements: Cryorolled samples with 90% RA show tensile yield strength (380 MPa) with an elongation only ~3.2%. The enhancement in yield strength of the cryorolled samples were found more compared to the Room Temperature Rolled (RTR) samples (YS = 230 MPa). Keywords: Cryorolling (CR), Electron Microscopy, Room Temperature Rolling (RTR), Tensile Yield Strength, Ultrafine Grains, Work Hardening