Effect of cold rolling on properties and microstructures of dispersion strengthened copper alloys
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;2. School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan)
Abstract: Mechanical properties and microstructures of unidirectionally and tandem rolled alumina dispersion strengthened copper(ADSC) alloys under different conditions were investigated by tensile test, optical microscopy(OM), transmission electron microscopy(TEM) and scanning electron microscopy(SEM). For unidirectionally rolled ADSC alloys, their strengths and elongations in the longitudinal direction are higher than those in the transverse direction under both cold rolling and annealing conditions. Once fracture appears in their longitudinal stress—strain curves, sudden reduction of overall stress level before complete fracture can be observed in the transverse tensile curves. The anisotropy of mechanical properties for the ADSC alloy can be greatly improved by tandem cold rolling. And no sudden reduction of overall stress level appears in the stress—strain curves for tandem rolled ADSC alloys. The differences of their microstructures and tensile fractures were analyzed. In order to compare the differences of tensile fracture mechanism in different directions, longitudinal and transverse fracture models for unidirectionally rolled ADSC alloys were also introduced.
Key words: dispersion strengthened copper alloy; unidirectional rolling; tandem rolling; annealing; fracture behavior