Microstructure Of Ti6Al4V Alloy Research Articles

Investigation of Microstructure, Mechanics, and Corrosion Properties of Ti6Al4V Alloy in Different Solutions

There is a scarcity of research on the characterization of the behaviour of titanium and its alloys in highly corrosive environments. These materials are highly recommended for use in various industries such as aviation, maritime, medical, and chemical, due to their perceived superior corrosion resistance. This research examines the mechanical and corrosion characteristics of Ti6Al4V material when exposed to solutions containing 9% NaCl, 25% HCl, and a mixture of 9% NaCl and 25% HCl. Prior to the corrosion process, the prefabricated Ti6Al4V samples underwent microstructure analysis, hardness assessment, and wear evaluation. The microstructure characterization revealed that the microstructure of the Ti6Al4V alloy is composed of α and modified β phases. The Ti6Al4V sample’s hardness value was determined to be 334.23 HB. The Ti6Al4V sample’s wear rate was determined to be 0.0033 g/Nm, while the friction coefficient was determined to be 0.0326. Corrosion testing was conducted at intervals of 24, 48, 72, 168, and 336 h. Based on the corrosion rate measurements, the sample exhibited the minimum corrosion rate of 1.928519 mg/(dm2·day) in a 9% NaCl environment. The sample with a combination of 9% NaCl and 25% HCl had the maximum corrosion rate, measured at 6.493048 mg per square decimetre per day. The formation of a larger oxide layer in the Ti6Al4V corrosion sample immersed in a 9% NaCl solution serves as a protective barrier on the surface and enhances its resistance to corrosion.

Nano-Mechanical Behavior of Ti6Al4V Alloy Manufactured Using Laser Powder Bed Fusion.

The microstructure of Ti6Al4V alloy, manufactured using laser powder bed fusion (L-PBF), is affected by process parameters and heat treatment. However, their influence on the nano-mechanical behavior of this widely applicable alloy is still unknown and scarcely reported. This study aims to investigate the influence of the frequently used annealing heat treatment on mechanical properties, strain-rate sensitivity, and creep behavior of L-PBF Ti6Al4V alloy. Furthermore, the influence of different utilized L-PBF laser power-scanning speed combinations on mechanical properties of annealed specimens has been studied as well. It has been found that the effect of high laser power remains present in the microstructure even after annealing, resulting in increase in nano-hardness. Moreover, the linear relation between the Young's modulus and the nano-hardness after annealing has been established. Thorough creep analysis revealed dislocation motion as a dominant deformation mechanism, both for as-built and annealed conditions of the specimens. Although annealing heat treatment is beneficial and widely recommended, it reduces the creep resistance of Ti6Al4V alloy manufactured using L-PBF. The results presented within this research article contribute to the L-PBF process parameter selection, as well as to understanding the creep behavior of these novel and widely applicable materials.

Effect of cooling rate during annealing on microstructure and ultrasonic cavitation behaviors of Ti6Al4V alloy

Crack propagation is one of the most important failure modes in cavitation erosion, which is microstructurally-sensitive. Thus, the microstructure of Ti6Al4V alloy was regulated by annealing with different cooling rates to investigate its cavitation erosion resistance in this study. The effect of microstructure evolution of Ti6Al4V alloy on its crack propagation behavior under ultrasonic cavitation was discussed in detail. The results showed that cracks firstly initiated at the interface between α/β phase and then extended to β phase surface under the impact of ultrasonic cavitation. Because of the existence of fewer slip systems, higher hardness and elastic resilience of α phase, as well as the existence of substructures inside of α phase, it was difficult to initiate and propagate cracks in α phase of Ti6Al4V alloy than β phase during cavitation erosion. Besides, the Ti6Al4V alloy after heat treatment with air cooling showed excellent cavitation erosion resistance. The reason came from two aspects that acicular secondary α grains precipitated inside of transformed β (βT) phase and nanotwins formed in the interface between βT phase and primary α phase, resulting in the better crack propagation resistance of Ti6Al4V alloy after heat treatment with air cooling.

Laser Butt Welding of Thin Ti6Al4V Sheets: Effects of Welding Parameters

Titanium and its alloys, particularly Ti6Al4V, which is widely utilized in the marine and aerospace industries, have played a vital role in different manufacturing industries. An efficient and cost-effective way of joining this metal is by laser welding. The effect of laser power and welding speed on the tensile, microhardness, and microstructure of Ti6Al4V alloy is investigated in this paper. Results show that the microhardness is highest at the fusion zone and reduces towards the base metal. The microstructure at the fusion zone shows a transformed needle-like lamellar α phase, with a martensitic α’ phase observed within the heat affected zone. Results of tensile tests show an improved tensile strength compared to the base metal.

Evolution of surface mechanical properties and microstructure of Ti[sbnd]6Al[sbnd]4V alloy induced by electropulsing-assisted ultrasonic surface rolling process

Effect of electropulsing-assisted ultrasonic surface rolling process (EP-USRP) on surface mechanical properties and microstructure of Ti6Al4V alloy was investigated. Compared with the original ultrasonic surface rolling process (USRP), the introduction of electropulsing with optimal parameters can effectively facilitate surface cracks healing, improve surface microhardness and wear resistance. In addition, the residual compressive stress is further enhanced ​under EP-USRP. Rapid improvement of the surface mechanical properties should be attributed to the ultra-refined grains and enhanced plastic deformation caused by the coupling effect of USRP and electropulsing. High strain rate given by USRP, the accelerated dislocation mobility and atom diffusion induced by electropulsing are likely the primary intrinsic reasons for the observed phenomena.

Influences of Hydrogenation on Microstructure and Microhardness of Ti6Al4V Alloy

The microstructures of Ti6Al4V alloy after hydrogenation have been investigated and analysed by optical microscopy (OM), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the influence of hydrogenation on the hardness of α and β phases has been analysed by microhardness testing. The microstructure observation revealed that δ hydride (fcc structure) precipitated in the specimens with 0.278 wt.% and 0.514 wt.% hydrogen, and a lot of dislocations and twins have been found simultaneously. The diffraction peaks moved to the lower angles because of the lattice expansion of β phase with the solution of hydrogen atoms. The result of microhardness testing shows that the hardness of α and β phases increases synchronously with increasing of hydrogen and the increment of β is larger than that of α. It is considered that the formation of δ hydrides, lattice defects and alloying element diffusion are the major factors leading to the microhardness change.