Characterization of fire-refined copper recycled from scrap

摘要

Certain properties of fire-refined copper recycledfrom scrap have been characterized. A method is presented tocalculate the half-softening temperature and the annealingtemperature that allows 30% elongation to failure, hereinafterreferred to as ?30% temperature, on the basis of hardnessmeasurements. The relation between ultimate strain and ultimateelongation has been studied and is described by a mathematicalexpression that seems to be independent of copper compositionand annealing temperature. The microstructure of annealedsamples reveals that recrystallization begins at half-softeningtemperature, and is ending at ?30% temperature, although graingrowth is not observed. An optimal range of oxygen content hasbeen found that gives the minimum ?30% temperature for eachstudied composition, and a mathematical expression with which tocalculate those minimum temperatures is developed. The influenceof cold-working degree on ?30% temperature is also described;these temperatures reach a constant minimum value for eachcomposition at high deformation degrees of cold-working.