Abstract
To study the microstructural evolution in high-strain-rate shear deformation of Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy, a series of forced shear tests of hat-shaped specimens have been conducted using a split Hopkinson pressure bar combined with the “strain-frozen” technique. A localized shear band is induced in Ti-55511 alloy in these tests. The experimental results demonstrate that the flow stress in hat-shaped specimens remains constant (about 600 MPa) and is independent of punching depth. The width of the adiabatic shear band increases with increasing punching depth and tends to saturate at 30 μm, and the estimation of the adiabatic shear band (ASB) width in hat-shaped (HS) specimens has been modified. Relying on the experimental results, thermal softening has a minor effect on the onset of the adiabatic shear band and dynamic recrystallization formation, and the nucleation mechanism for dynamic recrystallization is strain-induced boundary migration and subgrain rotation and coalescence. In addition, we suggest the concept of adhesive fracture as the dynamic failure mechanism for Ti-55511 alloy.
Highlights
IntroductionThe term “adiabatic shear band” (hereinafter referred to as ASB) has been widely accepted by researchers since it was first mentioned in the original report of Zener and Hollomon in 1944 [1]
The term “adiabatic shear band” has been widely accepted by researchers since it was first mentioned in the original report of Zener and Hollomon in 1944 [1]
A than seriesthat of dynamic shear tests were carried out on alloy at 293 by are means of higher calculatedforced for tantalum
Summary
The term “adiabatic shear band” (hereinafter referred to as ASB) has been widely accepted by researchers since it was first mentioned in the original report of Zener and Hollomon in 1944 [1]. ASB is an important failure mechanism of solid materials in high-strain-rate deformation, especially for titanium alloys [2]. A considerable number of investigations on titanium alloys under high-strain-rate loading conditions have been conducted over the last two decades [7,8,9,10,11]. Meyers et al [7] found a three-fold difference between measured width of ASB and predicted values, calculated by the criterion proposed by Bai et al [12] and Dodd and. Bai [13,14], in commercially pure α-titanium (TA2) hat-shaped (HS) specimens, while the measured width of ASB is slightly higher than the calculated results in Chen et al.’s work [15]. Nanograins with a size of 10–30 nm were observed by Rittel et al [9], while a subgrain of approximately 200 nm was observed by Meyers et al [7]
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