Effect of zinc content on the processing map for hot working of α brass

Abstract

The hot deformation behavior of α brass with varying zinc contents in the range 3%-30% was characterized using hot compression testing in the temperature range 600–900°C and strain rate range 0.001–100 s⁻¹. On the basis of the flow stress data, processing maps showing the variation of the efficiency of power dissipation (given by 2m/(m+1) where m is the strain rate sensitivity) with temperature and strain rate were obtained. α brass exhibits a domain of dynamic recrystallization (DRX) at temperatures greater than 0.85Tm and at strain rates lower than 1 s⁻¹. The maximum efficiency of power dissipation increases with increasing zinc content and is in the range 33%–53%. The DRX domain shifts to lower strain rates for higher zinc contents and the strain rate for peak efficiency is in the range 0.0001–0.05 s⁻¹. The results indicate that the DRX in α brass is controlled by the rate of interface formation (nucleation) which depends on the diffusion-controlled process of thermal recovery by climb.