Acoustic Assessment of Microstructural Deformation Mechanisms on a Cold Rolled Cu30Zn Brass

Autor: María Sosa, Linton Carvajal, Vicente Salinas Barrera, Fernando Lund, Claudio Aguilar, Felipe Castro Cerda
Jazyk: angličtina
Rok vydání: 2024
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Zdroj: Materials, Vol 17, Iss 13, p 3321 (2024)
Druh dokumentu: article
ISSN: 1996-1944
DOI: 10.3390/ma17133321
Popis: The relationship between acoustic parameters and the microstructure of a Cu30Zn brass plate subjected to plastic deformation was evaluated. The plate, previously annealed at 550 °C for 30 min, was cold rolled to reductions ranging from 10% to 70%. Linear ultrasonic measurements were performed on each of the nine specimens, corresponding to the nine different reductions, using the pulse-echo method to record the times of flight of longitudinal waves along the thickness axis. Subsequently, acoustic measurements were conducted to determine the nonlinear parameter β through second harmonic generation. Microstructural analysis, carried out by X-ray diffraction, Vickers hardness testing, and optical microscopy, revealed an increase in deformation twins, reaching a maximum at 40% thickness reduction. At higher deformations, the microstructure showed the generation and proliferation of shear bands, coinciding with a decrease in the twinning structure and an increase in dislocation density. The longitudinal wave velocity exhibited a 0.9% decrease at 20% deformation, attributed to dislocations and initial twin formation, followed by a continuous increase up to 2% beyond this point, resulting from the combined effects of twinning and shear banding. The nonlinear parameter β displayed a notable maximum, approximately one order of magnitude greater than its original value, at 40% deformation. This peak correlates with a roughly tenfold increase in twinning fault probability at the same deformation level.
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