2021 Volume 60 Issue 1 Pages 11-15
The heterogeneous–nano (HN) structure consisting of twin domains, shear bands, and lamellar grains developed by heavy cold rolling of FCC metals with low stacking fault energy is known to provide extremely high strength. In the present study, the effects of the rolling pass schedule on the development of HN structure and the mechanical properties in a Cu–38mass%Zn alloy were investigated. Two different rolling pass schedules were conducted； one was conventional unidirectional rolling (1–DR) up to 90% reduction in thickness, and the other was the two–directional rolling (2–DR) , in which the specimen was unidirectionally rolled to 25% reduction, then rotated 90° around the rolling direction, and subsequently, unidirectionally rolled up to total reduction of 90%. At total reduction of 50%, the number of grains with deformation twins in the 2–DR specimen was comparably higher than that in the 1–DR one. Further cold rolling up to 90% produced the HN structure in both specimens. The size of twin domains in the specimen fabricated by 2–DR was finer and their volume fraction was larger than those in the specimen processed by 1–DR. Also, the 2–DR specimen exhibited a better strength–elongation balance than the 1–DR specimen. It can be concluded that the finer size and larger volume fraction of the twin domain effectively improved the strength–elongation balance in the 2–DR specimen.
