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The purpose of this paper is to study and compare the mechanical properties and machinability characteristics of additive manufactured titanium alloy Ti-6Al-4V with conventionally produced wrought titanium alloy,Ti-6Al-4V. The difference in mechanical properties such as yield strength, ultimate tensile strength, micro hardness, percentage of elongation and their effect on machinability characteristics like cutting forces and surface roughness are studied. It was found that higher strength and hardness of SLM Ti-6Al-4V compared to wrought Ti-6Al-4V owing to its peculiar acicular microstructure significantly affected the cutting forces and surface roughness. High cutting forces and low surface roughness were observed during machining of additive manufactured components compared to its wrought counterpart because of their difference in strength, hardness and ductility.

Mechanical properties like yield strength, ultimate tensile strength, hardness and percentage of elongation and machinability characteristics like cutting forces and surface roughness were studied for both wrought and additive manufactured Ti-6Al-4V.

Mechanical properties like yield strength, ultimate tensile strength and hardness were higher for additive manufactured components as compared to the wrought component. However additive manufactured components significantly lacked in ductility as compared to the wrought parts. Concerning machining, higher cutting forces and lower surface roughness were observed in additive manufactured Ti-6Al-4V compared to the wrought part as a result of differences in mechanical properties of these differently processed materials.

This paper, for the first time, discusses the machining capabilities of additive manufactured Ti-6Al-4V.

This paper aims to evaluate the corrosion behavior of Ti-6Al-4V parts produced with electron beam melting (EBM) machine and compare it with wrought Ti-6Al-4V alloy.

Potentiodynamic and potentiostatic tests were applied on EBM Ti-6Al-4V in 3.5 per cent mass NaCl solution to determine the pitting potential and critical pitting temperature (CPT). A relation between pitting potential and temperature was established for EBM Ti-6Al-4V alloy by conducting potentiodynamic testing under different temperatures. CPT was also measured for EBM Ti-6Al-4V alloy in 3.5 per cent mass NaCl solution at a standard potential of 800 mV vs saturated calomel electrode (SCE). The same tests were performed on wrought Ti-6Al-4V for comparison purposes. Moreover, CPT for EBM Ti-6Al-4V alloy was measured in 3.5 per cent mass NaCl solution of different pH of 2.0, 5.7 and 10.0 to examine the effect of aggressive conditions on the pitting corrosion of EBM alloy.

Potentiodynamic test resulted in a relatively high pitting potential of EBM alloy, which was close to the pitting potential of wrought alloy even at higher temperatures. In addition, EBM samples did not pit when potentiostatic test was performed at 800 mV vs SCE, even at high and low values of pH.

EBM Ti-6Al-4V alloy has been increasingly playing an important role in aerospace, automobile and industrial fields. The technique and conditions of manufacturing form voids and increase roughness of the exterior surface of EBM objects, which might increase the tendency to initiate pitting corrosion within its holes and surface folds. This article shows that, despite surface variations and porosity in EBM Ti-6Al-4V alloy, the material maintained its corrosion resistance. It was found that the corrosion behavior of EBM alloy was close to that of the conventionally made wrought Ti-6Al-4V alloy.

Density optimization is the first critical step in building additively manufactured parts with high-quality and good mechanical properties. The authors developed an approach that combines simulations and experiments to identify processing parameters for high-density Ti-6Al-4V using the laser powder-bed-fusion technique. A processing diagram based on the normalized energy density concept is constructed, illustrating an optimized processing window for high- or low-density samples. Excellent mechanical properties are obtained for Ti-6Al-4V samples built from the optimized window.

The authors use simple, but approximate, simulations and selective experiments to design parameters for a limited set of single track experiments. The resulting melt-pool characteristics are then used to identify processing parameters for high-density pillars. A processing diagram is built and excellent mechanical properties are achieved in samples built from this window.

The authors find that the laser linear input energy has a much stronger effect on the melt-pool depth than the melt-pool width. A processing diagram based on normalized energy density and normalized hatch spacing was constructed, qualitatively indicating that high-density samples are produced in a region when 1 < E* < 2. The onset of void formation and low-density samples occur as E* moves beyond a value of 2. The as-built SLM Ti-6Al-4V shows excellent mechanical performance.

A combined approach of computer simulations and selected experiments is applied to optimize the density of Ti-6Al-4V, via laser powder-bed-fusion (L-PBF) technique. A series of high-density samples are achieved. Some special issues are identified for L-PBF processes of Ti-6Al-4V, including the powder particle sticking and part swelling issues. A processing diagram is constructed for Ti-6Al-4V, based on the normalized energy density and normalized hatch spacing concept. The diagram illustrates windows with high- and low-density samples. Good mechanical properties are achieved during tensile tests of near fully dense Ti-6Al-4V samples. These good properties are attributed to the success of density optimization processes.

With technology advances, metallic implants claim to improve the quality and durability of human life. In the recent decade, Ti-6Al-4V biomaterial has been additively manufactured via selective laser melting (SLM) for orthopedic applications. This paper aims to provide state-of-the-art on mechanobiology of these fabricated components.

A literature review has been done to explore the potential of SLM fabricated Ti-6Al-4V porous lattice structures (LS) as bone substitutes. The emphasize was on the effect of process parameters and porosity on mechanical and biological properties. The papers published since 2007 were considered here. The keywords used to search were porous Ti-6Al-4V, additive manufacturing, metal three-dimensional printing, osseointegration, porous LS, SLM, in vitro and in vivo.

The properties of SLM porous biomaterials were compared with different human bones, and bulk SLM fabricated Ti-6Al-4V structures. The comparison was also made between LS with different unit cells to find out whether there is any particular design that can mimic the human bone functionality and enhance osseointegration.

The implant porosity plays a crucial role in mechanical and biological characteristics that relies on the optimum controlled process variables and design attributes. It was also indicated that although the mechanical strength (compressive and fatigue) of porous LS is not mostly close to natural cortical bone, elastic modulus can be adjusted to match that of cortical or cancellous bone. Porous Ti-6Al-4V provide favorable bone formation. However, the effect of design variables on biological behavior cannot be fully conclusive as few studies have been dedicated to this.

In the present study, an attempt has been made to examine friction and wear behaviour of Ti-6Al-4V alloy sliding against EN-31 steel under lubricative media of common commercial grade oil (hydrol-68). The paper aims to discuss these issues.

Tribological properties of Ti-6Al-4V under hydrol-68 as lubricative media are measured using multi-tribo tester. Lubricating oil samples at different normal loads have also been analysed with the help of laser net fines (LNF) as per ISO 4406:1999. Experiments have been designed by two level full factorial method.

Experimental results indicate that the wear rate of Ti-6Al-4V alloy decreases as sliding speed increases. But it shows typical transition characteristics as the normal load increases; till 30 N wear rate decreases then it increases from 30 to 50 N. Also for all loads and at every speed, the average wear increases as the sliding distance increases. The average coefficient of friction of the Ti-6Al-4V alloy decreases with the increase in sliding velocity and normal load. Lubricating oil analysis indicates that the maximum wear particle size (5-15 μm) was obtained at a normal load of 50 N.

This paper shows that considerable reduction in friction and wear is achieved by using common grade oil hydrol-68 as lubricative media. Further, the analysis of lubricating oil using LNF at different normal loads indicates the co-existence of various wear phenomena such as cutting, fatigue, and sliding wear simultaneously.

This paper aims to describe the obtainment of Ti-6Al-4V parts with a hierarchical arrangement of pores by additive manufacturing, aiming at designing orthopedic implants.

The experimental methodology compares microstructural and mechanical properties of Menger pre-fractal sponges of Ti-6Al-4V alloy, manufactured by laser powder bed fusion (LPBF) and electron beam powder bed fusion (EBPBF), with three different porosity volumes. The pore arrangement followed the formation sequence of the Menger sponge, with hierarchical order from 1 to 3.

The LPBF parts presented a martensitic microstructure, while the EBPBF parts presented an α + ß microstructure, independently of its wall thickness. The LPBF parts presented higher mechanical resistance and effective stiffness than the EBPBF parts with similar porosity volume. The stiffness values of the Menger pre-fractal sponges of Ti-6Al-4V alloy, between 4 and 29 GPa, are comparable to those of the cortical bone. Furthermore, the deformation behavior presented by the Menger pre-fractal sponges of Ti-6Al-4V alloy did not follow the Gibson and Ashby model's prediction.

To the best of the authors' knowledge, this is the first study to obtain Menger pre-fractal sponges of Ti-6Al-4V alloy by LPBF and EBPBF. The deformation behavior of the obtained porous parts was contrasted with the Gibson and Ashby model's prediction.

The purpose of this paper is to examine the mechanical behaviour of additively manufactured Ti-6Al-4V under cyclic loading. Using as-built selective laser melting (SLM) Ti-6Al-4V in engineering applications requires a detailed understanding of its elastoplastic behaviour. This preliminary study intends to create a better understanding on the cyclic plasticity phenomena exhibited by this material under symmetric and asymmetric strain-controlled cyclic loading.

This paper investigates experimentally the cyclic elastoplastic behaviour of as-built SLM Ti-6Al-4V under symmetric and asymmetric strain-controlled loading histories and compares it to that of wrought Ti-6Al-4V. Moreover, a plasticity model has been customised to simulate effectively the mechanical behaviour of the as-built SLM Ti-6Al-4V. This model is formulated to account for the SLM Ti-6Al-4V-specific characteristics, under the strain-controlled experiments.

The elastoplastic behaviour of the as-built SLM Ti-6Al-4V has been compared to that of the wrought material, enabling characterisation of the cyclic transient phenomena under symmetric and asymmetric strain-controlled loadings. The test results have identified a difference in the strain-controlled cyclic phenomena in the as-build SLM Ti-6Al-4V when compared to its wrought counterpart, because of a difference in their microstructure. The plasticity model offers accurate simulation of the observed experimental behaviour in the SLM material.

Further investigation through a more extensive test campaign involving a wider set of strain-controlled loading cases, including multiaxial (biaxial) histories, is required for a more complete characterisation of the material performance.

The present investigation offers an advancement in the knowledge of cyclic transient effects exhibited by a typical α’ martensite SLM Ti-6Al-4V under symmetric and asymmetric strain-controlled tests. The research data and findings reported are among the very few reported so far in the literature.

The purpose of this study is to calibrate a microstructure-based fatigue model for its use in predicting fatigue life of additively manufactured (AM) Ti-6Al-4V. Fatigue models that are capable of better predicting the fatigue behavior of AM metals is required to further the adoption of such metals by various industries. The trustworthiness of AM metallic material is not well characterized, and fatigue models that consider unique microstructure and porosity inherent to AM parts are needed.

Various Ti-6Al-4V samples were additively manufactured using Laser Engineered Net Shaping (LENS), a direct laser deposition method. The porosity within the LENS samples, as well as their subsequent heat treatment, was varied to determine the effects of microstructure and defects on fatigue life. The as-built and heat-treated LENS samples, together with wrought Ti-6Al-4V samples, underwent fatigue testing and microstructure and fractographic inspection. The collected microstructure/defect statistics were used for calibrating a microstructure-sensitive fatigue model.

Fatigue lives of the LENS Ti-6Al-4V samples were found to be consistently less than those of the wrought Ti-6Al-4V samples, and this is attributed to the presence of pores/defects within the LENS material. Results further indicate that LENS Ti-6Al-4V fatigue lives, as predicted by the used microstructure-sensitive fatigue model, are in close agreement with experimental results. The used model could predict upper and lower prediction bounds based on defect statistics. All the fatigue data were found to be within the bounds predicted by the microstructure-sensitive fatigue model.

To further test the utility of microstructure-sensitive fatigue models for predicting fatigue life of AM samples, future studies on additional material types, additive manufacturing processes and heat treatments should be conducted.

This study shows the utility of a microstructure-sensitive fatigue model for use in predicting the fatigue life of LENS Ti-6Al-4V with various levels of porosity and while in a heat-treated condition.

The purpose of this paper is to consider the corrosion properties of laser nitrided Ti‐6Al‐4V alloys that have been reported previously by several researchers.

Different kinds of surface nitriding methods of titanium alloys, such as plasma nitriding, ion nitriding, gas and laser nitriding, are introduced. Microstructure changes, such as phase formation and the influence of laser processing parameters in laser nitriding layers of Ti‐6Al‐4V alloys, were investigated using scanning electron microscope, transmission electron microscope, X‐ray photo‐electron spectroscopy, and X‐ray diffraction. Based on investigations presented in the literature, the effect of laser nitriding on the corrosion behavior of Ti‐6Al‐4V alloy was reviewed.

By regulating the laser processing parameter, the microstructure of the nitrided layer can be controlled to optimize corrosion properties. This layer improves corrosion behavior in most environments, due to the formation of a continuous TiNxOy passive film, which can retard the ingress of corrosive ions into the substrate and can maintain a constant value of a current density. Therefore, the laser gas nitrided specimens have a relatively noble corrosion potential and a very small corrosion current, as compared to untreated specimens.

This paper comprises a critical review, and its collection of references is useful. It summarizes current knowledge in laser surface treatment research.

The purpose of this paper is to study formability, tensile properties, dislocation density and surface roughness of incrementally deformed Ti–6Al–4V alloy sheets during single-point incremental forming (SPIF) and multi-point incremental forming (MPIF) process. The development of corrosion pits in 3.5% NaCl solution has also been studied during SPIF and MPIF processes.

In this study, the formability, tensile properties, dislocation density, surface roughness and corrosion behaviour of deformed Ti–6Al–4V alloy sheets were studied. A potentio-dynamic polarization (PDP) study was conducted to study the corrosion behaviour of Ti–6Al–4V alloy samples during SPIF and MPIF processes and the results were also compared with base material (BM) in 3.5% NaCl solution. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses were carried out to study the corrosion morphology and dislocation densities of deformed samples.

The deformed Ti–6Al–4V alloy sheets obtained higher plastic deformation, high tensile strength, good surface roughness and good corrosion resistance during MPIF process when compared with SPIF process.

It has been concluded that the maximum strain and good corrosion resistance have been achieved with MPIF process, which in turn increases the plastic deformation as compared with BM.

This study discussed the formability, tensile properties, surface roughness and corrosion behaviour of deformed Ti–6Al –4V alloy sheets during incremental sheet forming (ISF) process.

This study is useful in the field of medical, industrial and automobile applications.

The Ti–6Al–4V alloy is deformed using MPIF process, achieving better formability, tensile strength, good surface roughness and corrosion rate, and the same is evidenced in forming limit diagrams (FLDs) and PDP curves.