Recrystallization Kinetics of the Severely Strained Commercially Pure Copper During Annealing at Half of its Melting Point

Severe plastic deformation (SPD) processing combined with subsequent annealing is a well-known approach for the grain refinement of metallic materials. Since the equal channel angular pressing (ECAP) is one of the promising processes developed for the imposition of SPD, different works have been focused on the effect of ECAP combined with subsequent annealing on the microstructure evolutions of commercially pure (CP) metals likes copper. However, most of the previous studies have considered relatively low annealing temperatures while the application of moderate annealing temperatures for this procedure has remained less studied. This work aims to investigate the recrystallization kinetics of ECAP processed CP-copper during annealing at half of its absolute melting point considering widely accepted theories for recrystallization quantification. For this purpose, CP-copper was processed by ۰,۱ and ۴ passes of ECAP at room temperature and afterwards, the ECAP processed specimens are subjected to different annealing periods at ۴۰۰℃. During this procedure, the fraction of recrystallized materials and the size of recrystallized grains is measured using optical microscopy. Results show that the imposition of one pass of ECAP combined with the subsequent annealing at ۴۰۰℃ causes a considerable grain refinement of the copper. However, the increase of the ECAP pass number has a limited effect on the decrease of grain size of the material. In addition, the growth of recrystallized grains follows the Burke-Trunbull model by a time exponent of one-quarter. Also, the volume fractions of recrystallized materials are fitted to the JMAK equation using the time exponent of ۱.

Keywords:

ECAP , annealing , CP-copper , grain size , recrystallization kinetics.