Low‐Temperature Annealing of Asymmetrically Cold‐Rolled Electrolytic Tough‐Pitch Copper: Anneal Hardening and Bimodal Microstructure

Abstract

In this research, 90% asymmetric unidirectional rolling and post‐annealing were applied to electrolytic tough‐pitch (ETP) copper. The effect of low‐temperature (200°C) annealing on the microstructure and texture evolution, mechanical, and electrical properties were investigated. Static recovery (SRV) was the main softening mechanism at the annealing time range of 1‐5 min. In contrast, complete static recrystallization (SRX) was observed after annealing for 10 min. Bimodal microstructure, consisting of coarse and fine grains was evolved for annealing times more than 10 minutes. With increasing the post‐annealing duration, the intensity of deformation and shear textures was continuously decreased, however, the recrystallization (Cube) orientation becomes stronger up to 11.2×R. After 1, 2, and 5 min of post‐annealing, the hardness, yield strength, tensile strength, ductility, and toughness of copper were higher than those of the 90% rolled sample due to annealing hardening. After 10 min of annealing, the hardness, yield strength, and tensile strength suddenly decreased and the ductility and toughness significantly enhanced owing to the complete recrystallization. With increasing the post‐annealing time, the fraction of flat surfaces was decreased and the fraction of ductile dimples was increased. With the post‐annealing time increasing from 1 to 120 min, the electrical conductivity gradually increased from 84.9%IACS to 96.7%IACS.This article is protected by copyright. All rights reserved.