Hot Ductility Behavior of the Electrolytic Tough Pitch Copper Having Different Initial Oxygen Content

The possible ductility troughs of tough pitch copper containing various oxygen contents were identified to determine the safe and unsafe thermomechanical processing domains. Tensile and compression tests were conducted in temperature range of 300-800°C. The critical strain of single/multiple peaks dynamic recrystallization decreased by increasing oxygen content up to 220 ppm, and again increased with further increment up to 390 ppm. The non-uniform elongation region increased by increasing the temperature, and above 500°C, it was the dominant portion of the tensile curves. The long post-uniform elongation was attributed to the occurrence of dynamic recrystallization which increased the resistance of the material to localized necking. Two ductility troughs (unsafe thermomechanical processing regions) were recognized at temperatures of 400±50°C and 600±50°C. The ductility drop regions shifted to lower temperatures with an increase in the strain rate. The variation of the oxygen content, however, did not have significant effects on the position of ductility drops. The current work also explores the fracture surface characteristics of the tensile tested specimens.