Microstructure of adiabatic shear bands in Ti6Al4V

Peirs, Jan; Tirry, Wim; Amin-Ahmadi, Behnam; Coghe, F.; Verleysen, Patricia; Rabet, L.; Schryvers, D.; Degrieck, Joris

doi:10.1016/j.matchar.2012.10.009

Cited by 116 publications

(37 citation statements)

References 37 publications

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“…Normally, adiabatic shearing is undesirable because the formation of ASBs makes the material to lose its load carrying and energy dissipation capacity and even to be failure [2] . On the other hand, recently developed adiabatic cutting and blanking techniques intentionally use the ASBs phenomenon [3] . Ti6Al4V is a widely used titanium alloy.…”

Section: Introductionmentioning

confidence: 99%

Studies on Adiabatic Shear Bands of Ti6Al4V after Hot Compression

Xu¹,

Yang

Yang³

2016

Proceedings of the 2nd Annual International Conference on Advanced Material Engineering (AME 2016)

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Section: Introductionmentioning

confidence: 99%

Studies on Adiabatic Shear Bands of Ti6Al4V after Hot Compression

Xu¹,

Yang

Yang³

2016

Proceedings of the 2nd Annual International Conference on Advanced Material Engineering (AME 2016)

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“…Adiabatic shear banding is a typical materials phenomenon associated with shear localization and also an important thermoviscoplastic instability mode observed in metals when processed at high strain rates (>1 9 10 3 s À1 ) (Ref 3). Adiabatic shear bands are often observed in titanium and its alloys (Ref [4][5][6][7][8][9] due to the properties of low heat conductivity and high adiabatic shearing sensitivity. The microstructures of an adiabatic shear band in metals have the following characteristics: the center of bands is composed of ultrafine-equiaxed grains of diameters 0.03-0.5 lm, and the microstructure shows a distinct boundary from the shear band to the matrix ( Ref 8,9).…”

Section: Introductionmentioning

confidence: 99%

Shear Localization and its Related Microstructure Mechanism in a Fine-Grain-Sized Near-Beta Ti Alloy

Wang

Sun

Hahn

et al. 2014

J. of Materi Eng and Perform

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Shear localization is an important deformation and failure mechanism for the high strength near beta finegrain-sized titanium alloy used in aircraftÕs gear at high rate deformation. Hat-shaped specimens are used to induce the formation of an adiabatic shear band under controlled shock-loading tests. Unstable shear deformation of the alloy emerges after the true flow stress reaches 1147 MPa, the first vibration peak during the split Hopkinson pressure bar testing, and the whole process lasts about 68 ls. The microstructures within the shear band in the alloy are investigated by means of light microscopy, scanning electron microscopy, and transmission electron microscopy. The results show that the grains in the boundary of the shear band are highly elongated along the shear direction, and the core of the shear band consists of ultrafine-equiaxed grains with diameters 0.1-0.3 lm, low dislocation density, and no observed phase transformation. The rotational dynamic recrystallization is used to explain the microstructural evolution mechanism in the shear band. Kinetic calculations indicate that the recrystallized ultrafine grains are formed during the deformation and do not undergo significant growth by grain boundary migration after deformation.

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“…It is always reported that the flow softening would happen with the formation of adiabatic shear bands [185,186,250,253] in the high strain rate deformation. However, the curve shown in Fig.3 (a) maintains a plateau trend after yielding until the unloading.…”

Section: Discussionmentioning

confidence: 99%

“…Because of their low strain hardening rates and poor thermal conductivity, titanium alloys are recognized to be very susceptible to adiabatic shear bands [184,185] and an optical image of an adiabatic shear band in the Ti-6Al-4V alloy is shown in Fig.19. Most studies on the ASBs in titanium alloys focus on Ti-6Al-4V [186][187][188][189] and commercially pure titanium [190,191] and few focus on β-Ti alloys. In this section, we do not focus on any specific metals or alloys in order to give a complete perspective of ASB formation.…”

Section: Adiabatic Shear Bandmentioning

confidence: 99%

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The dynamic response of β titanium alloys to high strain rates at room and elevated temperatures

Zhan¹

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Titanium and its alloys fulfil a wide range of applications involving aerospace, biomedical, chemical and petroleum industries due to their extraordinary properties such as high specific strength, excellent biocompatibility and corrosion resistance. Among different types of titanium alloys, β titanium alloys have a unique range of properties such as an excellent combination of high strength and fracture toughness and low Young's modulus. Therefore, the usage of β titanium alloys in the manufacturing of some key components in aerospace and biomedical industries has continually increased in the past decade.Nowadays many commercial manufacturing processes for metallic materials such as machining, explosive welding, hot forging and extrusion employ high strain rates and are conducted at elevated temperatures. Also, high-strain-rate deformation can be encountered in collisions such as in car crashes, bird strikes on airplanes and micrometeorite impacts on space structures. Hence a large number of studies have been conducted on the dynamic response of metallic materials including copper, steels, tantalum, Ti-6Al-4V alloy and commercially pure titanium to high strain rates. Due to limited knowledge of the dynamic behaviour of β titanium alloys, this thesis mainly investigates the stress-strain behaviour and microstructural evolution of β titanium alloys under high strain rates at room and elevated temperatures.Split Hopkinson Pressure Bar compressive tests were carried out on two new types of β titanium alloys with different levels of β phase stability, the Ti-6Cr-5Mo-5V-4Al (wt. %) and Ti-25Nb-3Zr-3Mo-2Sn (wt.%) alloys, at strain rates ranging from 10 -3 s -1 to 10 4 s -1 and temperatures ranging from 293K to 1173K. The Ti-6Cr-5Mo-5V-4Al alloy, with relatively high β phase stability, represents an alloy type which can be engineered through heat treatment or thermo-mechanical processing to achieve a superior combination of strength and fracture toughness. While the Ti-25Nb-3Zr-3Mo-2Sn alloy with relatively low β phase stability represents an alloy type which can be applied in biomedical applications due to their low Young's modulus and superelastic properties.For the Ti-6Cr-5Mo-5V-4Al alloy, dislocation slip is dominant at all testing strain rates and temperatures in this research. The flow stress increases with increasing strain rate but decreasing temperature. Also, it is more sensitive to temperature than strain rate. At ambient temperatures, the strain hardening rate exhibited by the Ti-6Cr-5Mo-5V-4Al alloy at high strain rates is much lower than that at quasi-static strain rates, which is attributed to the thermal softening effect brought byHongyi Zhan II The University of Queensland adiabatic heating. While for the Ti-25Nb-3Zr-3Mo-2Sn alloy, multiple deformation mechanisms including dislocation slip, {332} <113> and {112} <111> mechanical twinning, stress-induced martensitic α" and ω phase transformations can be activated simultaneously and among them {332} <113> twinning is dominant at 293K regardless of...

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Microstructure of adiabatic shear bands in Ti6Al4V

Cited by 116 publications

References 37 publications

Studies on Adiabatic Shear Bands of Ti6Al4V after Hot Compression

Studies on Adiabatic Shear Bands of Ti6Al4V after Hot Compression

Shear Localization and its Related Microstructure Mechanism in a Fine-Grain-Sized Near-Beta Ti Alloy

The dynamic response of β titanium alloys to high strain rates at room and elevated temperatures

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