Influence of Hot Rolling Temperature on Microstructural Evolution and Mechanical Properties of PM Copper Strip

Abstract

Evolution of the microstructure in porous metal strip during hot rolling is considered in terms of elimination of porosities, softening mechanisms, and aspect ratios of grains in as rolled full density strip. The elimination of porosity is unaffected by hot rolling temperature, and neither dynamic nor static softening mechanisms operate in any significant manner for copper strip of initial relative density around 0·35, given a thickness reduction of >80%. The aspect ratio of grains in full density strips obtained by single pass hot rolling, however, is significantly affected by rolling temperature. Tensile strength, 0·2% yield strength, and per cent elongation of strips have also been found to vary with the temperature of rolling. Fractographs of strip rolled at 823 and 923 K show intergranular fracture, indicating that insufficient interparticle bond strength is achieved at these temperatures; as rolling temperature increases the fracture surface reveals dimpled areas suggesting improved interparticle bond strength at higher temperature. PM/0706