Rationalization of duplex brass hot deformation behavior: The role of microstructural components

摘要

The sharing role of microstructural micro-constituents on hot deformation behavior of a 60/40 duplex brass was investigated through hot compression testing at predetermined temperatures in the range of 400-800 ℃ under the strain rates ranging from 0.001 to 0.1 s~(-1). The hot working parameters (strain rate sensitivity, and apparent activation energy, Q) were determined for different conditions of the applied thermomechanical processing. Assuming the Hyperbolic Sine functional behavior to analysis the deformation behavior of the alloy and also applying the rule of mixture in order to determine the share of each phase in strain accommodation, the interaction coefficients of alpha phase, P, and beta phase, R, were precisely estimated. The results indicate that the experimental material exhibits usual Dynamic Recrystallization (DRX) behavior such as single-phase materials; but in comparison to the conventional alloys DRX is postponed at 500 and 600 ℃. Moreover, it is seen that the deformation mechanism at different temperatures has been severely depend on the order-disorder transformation of the beta phase in mixture. In fact this transformation is considered to play the main role in beta phase recrystallization retardation. However, at lower Zener Holloman (Z) values, the strain accommodation is mainly taken place in beta phase and the chief deformation mechanism is believed to be grain boundary sliding (GBS). Accordingly there crystallization of alpha phase is limited due to the lower strain accommodation. In contrast, at higher Z values, the alpha phase controls the governing deformation mechanism and the dynamic recrystallization of alpha grains may well lead to the microstructural grain refinement.