The effect of rotary swaging on the microstructure and mechanical properties of brass L63 alloyed with Sn

Abstract

A study of the microstructure and mechanical characteristics of L63 brass alloyed with Sn after rotary swaging (RS) and additional annealing was conducted. It was shown that RS leads to the decomposition of the supersaturated α solution and the release of the β-phase, the proportion of which increases with increasing degree of deformation (ε). In addition, an ultrafine-grained (UFG) structure is formed inside the α-phase grains after RS at ε = 2.31. It consists of subgrains with a size of about 500 nm, shear bands with a width of 200 to 500 nm, and deformation twins with a width of 50–100 nm. Subsequent heating of the alloy after RS at ε = 2.31 leads to additional precipitation of the β-phase inside the grains of the α-phase, the proportion of which increases with increasing annealing duration. It was established that RS increases the strength properties of Sn-alloyed L63 brass without significantly reducing ductility. Additional heating at 350°C initially increases the strength and ductility of the alloy due to relaxation and recovery processes, as well as an increase in the proportion of the β-phase. However, as the annealing duration increases and, accordingly, the proportion of β-phase, the strength and ductility of the alloy decrease again. The yield stress, ultimate tensile strength and elongation of L63 brass alloyed with Sn increased to 476 ± 10 MPa, 639 ± 3 MPa and 12.2 ± 0.7%, respectively, after RS at ε = 2.31 and subsequent heating at 350 °C for 30 minutes.