Experimental Correlation of Mechanical Properties of the Ti-6Al-4V Alloy at Different Length Scales

Víctor Tuninetti,Joan Josep Roa,Carlos Rojas-Ulloa,Carlos Medina,Antonio Manuel Mateo,Guiomar Riu,Amna Znaidi,Andrés Felipe Jaramillo

doi:10.3390/met11010104

Víctor Tuninetti, Joan Josep Roa + Show 6 more

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This article focuses on a systematic study of a Ti-6Al-4V alloy in order to extensively characterize the main mechanical properties at the macro-, micro- and submicrometric length scale under different stress fields. Hardness, elastic modulus, true stress–strain curves and strain-hardening exponent are correlated with the intrinsic properties of the α- and β-phases that constitute this alloy. A systematic characterization process followed, considering the anisotropic effect on both orthogonal crystallographic directions, as well as determining the intrinsic properties for the α-phase. An analytical relationship was established between the flow stress determined under different stress fields, testing geometries and length scales, highlighting that it is possible to estimate flow stress under compression and/or tensile loading from the composite hardness value obtained by instrumented nanoindentation testing.

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IntroductionTitanium alloys are attractive engineering materials for the aerospace industry, mainly because of their high specific strength and ductility at low and moderate temperatures [1,2,3]
Titanium alloys are attractive engineering materials for the aerospace industry, mainly because of their high specific strength and ductility at low and moderate temperatures [1,2,3].In particular, Ti-6Al-4V is the most widely used titanium alloy due to a proper balance of processing characteristics such as good castability, plastic workability, heat treatability and weldability [4]
Hcomposite refers to the composite bulk material properties, Equation (2) can be rewritten in terms of the composite nanoindentation hardness as follows: σflow,tensile = 0.908 + 5.56 × 10−3·Hcomposite. This predictive model has a potential practical implication since by only measuring a single mechanical property, the flow stress under different deformation fields can be obtained at the macroscopic length scale, avoiding the machining of both tension and compression specimens, of which the procedure is expensive, time and material consuming and cumbersome to perform in the industry

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Introduction

Titanium alloys are attractive engineering materials for the aerospace industry, mainly because of their high specific strength and ductility at low and moderate temperatures [1,2,3]. Ti-6Al-4V is the most widely used titanium alloy due to a proper balance of processing characteristics such as good castability, plastic workability, heat treatability and weldability [4]. The predominant constituent phase of this Ti-alloy, low-symmetry hexagonal-structured α-phase, as well as α-/β-interfaces, exhibit remarkable elastic and plastic anisotropy [8,9]. The primary cause of the anisotropic behavior of polycrystalline alloys is the preferred orientation of grains, crystallographic textures, due to working processes [10]. Properties of polycrystals can be computed as averages of weighted values from the individual crystal orientations based on the texture [11]

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