Dynamic Deformation and High Velocity Impact Behaviors of Ti-6Al-4V Alloys

Abstract

Deformation behaviors under quasi-static and dynamic compression and high velocity impact condition of Ti-6Al-4V ELI (extra low interstitial) alloys in two different conditions were investigated. Mill annealed (MA) alloy, consisted of equiaxed α, and thermomechanically treated (TMT) alloy, consisted of mixed structure of equiaxed α and transformed β, were prepared. Compression tests were performed in low strain rate regime using hydraulic testing machine and were performed in high strain rate regime using split Hopkinson pressure bar. High velocity impact tests were also performed by impacting the test projectiles made of these alloys against a steel target at a velocity of ~400m/s. The compression test results showed that deformation behaviors were influenced by the strain hardening exponent at low strain rate regime, and by both the strain hardening exponent and the strain-rate hardening rate at high strain rate regime. TMT alloy showed higher strength but almost similar fracture strain as MA alloy at a high strain rate of ~6000/s, due to the effect of strain-rate hardening. The high velocity impact test results showed that the projectile of TMT alloy withstood without fracture at higher impact velocity, but the maximum amounts of deformation prior to crack were nearly the same for both alloys. These results were in accord with the results of compression tests at high strain rate regime, that is, higher strength but same fracture strain of TMT alloy compared to MA alloy.

Eigenstrain modelling of residual stress generated by arrays of laser shock peening shots and determination of the complete stress field using limited strain measurements

“…This decrease in the additional eigenstrain introduced with each successive layer is due to the pre-existing residual stress state, which acts to inhibit further yield of the material. With a work-hardening material this effect will be even marked, although it should be noted that Ti-6Al-4V shows very low levels of work hardening [14] and the material model assumed here is probably appropriate.…”

Residual stress in geometric features subjected to laser shock peening

“…Titanium alloy Ti–6Al–4V was chosen in the present study because of its use in compressor blades of aircraft engines. Typically, the level of work hardening in the material is not marked, 6 and an elastic/perfectly plastic behaviour (yield stress = 1000 MPa; Young's modulus = 110 GPa; Poisson's ratio = 0.3; and density = 4400 kg/m 3 ) was assumed in the current analyses; this is satisfactory for the purpose of validating the approach. 1–3 The results of earlier analyses 1–2 show that during LSP, material will be subject to high strain rates (∼10 6 s −1 ).…”

“…Titanium alloy Ti-6Al-4V was chosen in the present study because of its use in compressor blades of aircraft engines. Typically, the level of work hardening in the material is not marked 6 , and an elastic/perfectly-plastic behaviour (yield stress =1000 MPa;…”

“…The specific example is shown in Figure 1a and consists of a 16×8×8 mm Ti-6Al-4V specimen, 6 peened by two pulses (each 3×3 mm in size; laser power density (I) = 9 GW/cm 2 ; and laser pulse duration (t L )=18 ns) on the two surfaces adjacent to the free edge. For simplicity it was assumed that the shots were applied at the centre of the block in the x direction.…”

Penetration Damaging Behavior of TB17 Titanium Alloy

“…Titanium alloys have been investigated for their application as an armor technology, and technical papers about the possible replacement of steel with titanium alloy were published in many journals [4][5][6][7][8][9][10][11][12][13][14][15][16]. As early as 1950, the researchers found that titanium alloys have an application prospect as armors against small arms projectiles [4].…”