Effect of post-heat-treatment in ECAP processed Cu–40%Zn brass

This study evaluated the grain refinement and mechanical properties of Cu–40%Zn brass processed by equal channel angular pressing (ECAP). The samples were repeatedly pressed to strains as high as 4 at a temperature of 250 °C using route C. Recrystallization heat-treatment was carried out at 350 °C for 20 min. To evaluate the grain boundary character distributions and mechanical properties of ECAP materials, electron backscattered diffraction, Vickers microhardness, and tensile tests were used. Increased passes in ECAP led to notable grain refinement, from 13 μm in the initial sample (350 °C/180 min heat-treated material) to 300 nm after 4 passes. The post-heat-treated material after ECAP also sustained refined grain size (2.4 μm in the α phase and 4 μm in the β′ phase) than that of initial state, which resulted in an increase in tensile strength with no decrease in elongation. Furthermore, coincidence site lattice boundaries derived from annealing twins were more developed than those of the initial material. This paper discusses the enhancement of mechanical properties in terms of grain boundary character distributions development.

► We evaluated the grain refinement and mechanical properties of ECAP processed Cu–40%Zn brass.
► Increased passes in ECAP led to the notable grain refinement.
► The post-heat-treated material after ECAP also sustained refined grain size.
► These refined grains directly affect the improvement of mechanical properties such as microhardness and tensile strength.