Unveiling the room-temperature softening phenomenon and texture evolution in room-temperature- and cryogenic-rolled ETP copper

Self-Annealing Phenomena in the Cold-Rolled and Cryo-Rolled Copper Alloys: A Review

“…Self-annealing phenomena depend not only on material properties, such as pure metals/alloys or low/high melting point, but also on strain, strain rate, stacking fault energy, and deformation temperature [1]. Self-annealing can also decrease the micro-hardness values, which were reported for CR FCC materials [4,6].…”

“…For CR, specimens were dipped in the liquid nitrogen for more than 8 min before every pass. Detailed discussions on sample preparation for both alloys can be found elsewhere [4,7]. Similarly, Cu-0.13Sn-0.04Mg alloys sheets were only subjected to RTR deformation until a 75% RR.…”

“…Grain boundary bulging, as well as recovered microstructure, have been reported for the CR Cu [2]. These bulges forms due to the pinning effect of dislocations at grain boundaries (GBs), which initiates the formation of new SRX grains [4]. High defect densities, such as vacancy and other lattice defects, can arise during deformation at CT. A high density of lattice defects decrease the thermal stability of IOP Publishing doi:10.1088/1742-6596/2635/1/012015 2 Cu and its alloys, causing grain boundary migration even at the RT [5].…”

“…Heterogeneous deformation, formation of SBs, mechanical twinning, grain fragmentation were observed for the 93% CR Cu [2]. The phenomenon of recrystallization at RT is rare in Cu alloys and has not been extensively discussed in works on thermomechanically processed Cu alloys [4,5]. RT recrystallization, also known as self-annealing, was reported for CR Cu, indicating the nucleation of small grains, dislocation annihilation, and the evolution of a recovered microstructure in deformed Cu when samples are exposed to RT [2].…”

An eco-friendly electric pulse treatment process for improving the microstructure and properties of cold-rolled pure copper sheet

“…Copper and copper alloy sheets and strips are typical copper processed products, and their typical manufacturing methods mainly include Semicontinuous casting and thermo-roll forming, continuous casting and rolling forming, and continuous extrusion and rolling forming, no matter what kind of production method, before getting the required products, will go through the process of 'cold rolling → heat treatment' [3][4][5]. During the cold-rolling process, the grains of copper sheets slip and rotate, forming a cold-rolled texture and generating a large number of point defects, dislocations, and other crystal defects [6,7], so heat treatment is usually required after cold rolling to regulate the microstructure of cold-rolled copper sheets for subsequent forming or to obtain products with the desired properties [8,9]. Heat treatment is usually performed in a hot furnace, which provides the required thermal energy by conduction or radiation.…”