Selective Laser Melting Ti6Al4V Research Articles

Anodized SLM Ti6Al4V surfaces: influence of surface characteristics on NTs growth and resulted surfaces properties.

TiO2 nanotubes (NTs) obtained via electrochemical anodization (EA) on conventionally machined titanium surfaces are reported to be promising for achieving mucointegration in dental implant therapy. Dental abutments, manufactured by selective laser melting (SLM), combined with thermal post-treatment, present a promising alternative to conventionally machined titanium. Based on an original protocol, this study aims to investigate how the characteristic microstructure of the α + β phases in post-heated SLM Ti6Al4V can influence the growth of NTs and the resulting physical and chemical surface properties. Ti6Al4V-SLM discs were fabricated, heat post-treated and mechanically polished. The samples were then subjected to EA under different voltage conditions (10, 20 and 30 V). The specimens' surfaces were characterized at the same location, before NTs formation by electron backscatter diffraction (EBSD), and after by scanning electron microscopy (SEM). Then, roughness and wettability were studied to determine how EA affects surface properties compared to conventionally machined and polished titanium surfaces without NTs (reference). Surface reactivity was evaluated through chemical analysis and collagen binding capacities. The self-organized TiO2 layer was developed on the α phase only and the β phase was preferentially dissolved. The characteristic dimensions of the nanotubes (diameter, length and wall thickness), measured by SEM image analysis, increased proportionally with the rise in voltage but were not affected by the crystallographic orientation of the underlying α grain. Micro-roughness was the same for nanotubular and reference surfaces. Wettability was improved, as was surface reactivity towards collagen, which may contribute to improved bioactivity of titanium surfaces in dentistry.

Design, fabrication, and clinical characterization of additively manufactured tantalum hip joint prosthesis

Abstract The joint prosthesis plays a vital role in the outcome of total hip arthroplasty. The key factors that determine the performance of joint prostheses are the materials used and the structural design of the prosthesis. This study aimed to fabricate a porous tantalum (Ta) hip prosthesis using selective laser melting (SLM) technology. The feasibility of SLM Ta use in hip prosthesis was verified by studying its chemical composition, metallographic structure, and mechanical properties. In vitro experiments proved that SLM Ta exhibited better biological activities in promoting osteogenesis and inhibiting inflammation than SLM Ti6Al4V. Then, the topological optimization design of the femoral stem of the SLM Ta hip prosthesis was carried out by finite element simulation, and the fatigue performance of the optimized prosthesis was tested to verify the biomechanical safety of the prosthesis. A porous Ta acetabulum cup was also designed and fabricated using SLM. Its mechanical properties were then studied. Finally, clinical trials were conducted to verify the clinical efficacy of the SLM Ta hip prosthesis. The porous structure could reduce the weight of the prosthesis and stress shielding and avoid bone resorption around the prosthesis. In addition, anti-infection drugs can also be loaded into the pores for infection treatment. The acetabular cup can be custom-designed based on the severity of bone loss on the acetabular side, and the integrated acetabular cup can repair the acetabular bone defect while achieving the function of the acetabular cup.

Correction to [Development of Heat Treatments for Selective Laser Melting Ti6Al4V Alloy: Effect on Microstructure, Mechanical Properties, and Corrosion Resistance

Correction to [Development of Heat Treatments for Selective Laser Melting Ti6Al4V Alloy: Effect on Microstructure, Mechanical Properties, and Corrosion Resistance

The effect of doping different amounts of boron on the corrosion resistance and biocompatibility of TiO2 nanotubes synthesized on SLM Ti6Al4V samples

This comprehensive study investigates the corrosion and biocompatibility performances of boron-doped TiO2 nanotubes (TNT) synthesized on Ti6Al4V alloy produced by the selective laser melting (SLM) process. Structural analysis reveals a consistent reduction in nanotube diameter across varying boron doping levels (0.05 - 2 M boric acid doping), with B4-TNT exhibiting the smallest diameter at 190 nm. Boron incorporation induces phase transformation and decreases in diameter of nanotubes, influencing the material's structural properties. Corrosion resistance assessments indicate a significant enhancement, with B4-TNT demonstrating the highest polarization resistance (Rt = 2849.03 kΩ.cm2). The observed improvements are attributed to the combination of reduced nanotube diameter, altered phase structure, and increased polarization resistance, collectively contributing to enhanced corrosion resistance. Biocompatibility experiments conducted with human fibroblast cells (HDFa) reveal that B-doped TNTs foster increased cell viability compared to undoped TNT and uncoated alloy surfaces. These findings underscore the potential of boron doping as a strategic approach to improve corrosion resistance and enhance the biocompatibility of Ti6Al4V implants. This study provides valuable insights for advancing materials in biomedical applications with improved structural, corrosion-resistant, and biocompatible properties.

Characteristics and biological responses of selective laser melted Ti6Al4V modified by micro-arc oxidation

Background/purposeAdditive manufacturing (AM) technology, such as selective laser melting (SLM), has been used to fabricate medical devices of Ti-6wt.% Al-4wt.%V (Ti6Al4V) alloys in dentistry. Strontium (Sr) has been shown to have the potential to treat osteoporosis. The aim of this study was to investigate the physicochemical and biological properties of strontium-containing coatings on selective laser melted Ti6Al4V (SLM-Ti6Al4V) substrate. Materials and methodsThe disk of Ti6Al4V was prepared by SLM method. The strontium-containing coatings were prepared by micro-arc oxidation (MAO) in aqueous electrolytes. The surface topography, chemical composition, and phase of strontium-containing MAO (SrMAO) coatings were performed by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), and thin film X-ray diffraction (TF-XRD), respectively. The apatite-forming ability of the MAO coatings was conducted in simulating body fluid (SBF), and the cell proliferation was determined by methylthiazoletetrazolium (MTT) assay. ResultsThe microstructure of SLM-Ti6Al4V displays acicular α-phase organization. The TF-XRD results indicated that the phase of SrMAO coating was anatase, rutile, and titanium. The calcium, phosphorus, and strontium were detected in the coatings by EDS. Using the SEM, the surface morphology of SrMAO coatings exhibited a uniform 3D porous structure. The SrMAO coatings could induce a bone-like apatite layer after immersion in SBF, and presented significantly higher cell proliferation than untreated specimens in in-vitro experiments. ConclusionAll findings in this study indicate that SrMAO coatings formed on SLM-Ti6Al4V surfaces exhibit a benefit on biological responses and thereby are suitable for biomedical applications.

Multi-build orientation effects on microstructural evolution and mechanical behavior of truly as-built selective laser melting Ti6Al4V alloys

The unique combination of lightweight, strength, corrosion resistance, high-temperature resistance, and biocompatibility make Ti6Al4V alloy an important material in metal contact of solar cells, and selective laser melting (SLM) enables the production of Ti6Al4V parts complex geometries that would be difficult or impossible to produce using traditional manufacturing methods. The build orientation of SLM process presents an essential effect on the quality of the produced parts, and thus, in this study it investigates the impact of multi-build orientation (0°, 30°, 45°, 60°, 90°) on the microstructural evolution and mechanical behavior of truly as-built Ti6Al4V alloys produced by SLM. The microstructure analysis revealed the presence of ordered subsurface pores, located at a distance of about 50 μm–150 μm from the sample surface. The microstructure consisted primarily of α′ martensite with a small amount of β phase. Massive transformation was observed in the 30° and 45° samples, with corresponding grain sizes of 5 μm and 10 μm, respectively. To be specific, the content of β phase and ultimate tensile strength (UTS) varied with the sample orientation, and the 45° build orientation exhibited the highest content of β phase with value of approximately 2.8%, but also the lowest UTS and elongation, which were 1161 MPa and 3.99%, respectively.

Effect of heat treatments on mechanical properties and wear resistance of laser-powder bed-fused Ti6Al4V alloy

The effects of heat treatment on the microstructure, mechanical properties and wear resistance of Selective Laser Melting Ti6Al4V alloy were systematically studied. The results show that the as-built part has an acicular [Formula: see text] martensite structure. The increase in heat treatment temperature causes the decomposition of acicular [Formula: see text] martensite, which leads to the decrease of the hardness of Ti6Al4V alloy. When the heat treatment temperature is 800∘C, the alloy forms an [Formula: see text]/[Formula: see text] structure, which increases the tensile strength and elongation of the alloy by 12% and 23%, respectively. When the heat treatment reaches above 900∘C, the mechanical properties of the alloy decrease sharply due to the disappearance of the [Formula: see text]/[Formula: see text] structure, the coarse grains of the [Formula: see text] phase, and the increase of the content of the [Formula: see text] phase. The tensile strength decreased from 935[Formula: see text]MPa to 815[Formula: see text]MPa, and the elongation decreased from 8.7% to 3.1%. With the increase of heat treatment temperature, the friction coefficient and wear rate increase linearly, which is opposite to the changing trend of hardness, and the wear mechanism is changed from single abrasive wear to abrasive wear and oxidative wear. This is attributed to the increase in the grain size of the alloy and the increase in the content of the [Formula: see text] phase, resulting in a decrease in the overall hardness of the alloy.

Refinement of α′ Martensite by Oxygen in Selective Laser Melted Ti–6Al–4V

Refinement of α′ Martensite by Oxygen in Selective Laser Melted Ti–6Al–4V

Mechanism of impact toughness enhancement obtained by globularization of αGB phase for selective laser melted Ti–6Al–4V alloy

The low impact toughness of selective laser melted (SLM) Ti–6Al–4V (Ti64) is a main factor limiting its widespread application in engineering. In this work, we've greatly improved its toughness by modifying the morphology of the α phase via annealing. Specifically, the as-built sample had a toughness of 14.87J/cm2. Annealing at 800 °C for 4 h boosted the toughness to 25J/cm2. Notably, annealing at 950 °C for 4 h increased the toughness by a remarkable 90 %, reaching an impressive 36.88J/cm2, which is comparable to its wrought counterpart. Particularly, 950 °C annealing induces the globularization of αGB phase (α phase along prior β grain boundary) while maintains the lamellar morphology of the α phase within the prior β grain. This mixed structure significantly outperforms the full lamellar structure in the 800 °C annealed sample in terms of toughness. The mechanism of toughness enhancement differs from the traditional one where thick lamellar α phase improves the toughness by increasing the crack path's tortuosity. Our study indicates that more deformation twins are activated in 950°C-annealed samples in impact test, which effectively absorb additional impact energy and improve toughness. In the 800°C-annealed sample, only a limited number of grains with specific orientations can activate deformation twins. Whereas in the 950°C-annealed sample, a broader range of grain orientations demonstrated the capability to activate deformation twins. The mechanism for twin activation in the 950°C-annealed sample is proposed. It is associated with equiaxed αGB, inducing significant interface deformation accompanied by stress concentration. This ultimately leads to the formation of the deformation twins.

Enhanced low cycle fatigue properties of selective laser melting Ti–6Al–4V with fine-tuned composition and optimized microstructure

Improving the low-cycle fatigue (LCF) properties of additively manufactured Ti–5.6Al–3.8V alloy is critical in ensuring its service safety and represents a significant research challenge. This work discusses a solution that optimizes the alloy's microstructure and ductility by precisely controlling the over-saturated strengthening elements and heat treatment. This was accomplished using selective laser melting (SLM), heat treatment at 800 °C for 2 h, and furnace cooling on a Ti–5.6Al–3.8V alloy with tightly controlled Al, V, and O concentrations in a lower range. The results showed that the SLM-fabricated Ti–5.6Al–3.8V alloy, post-heat treatment, exhibited α laths with a width of ∼1.4 μm and β columnar grains with a diameter of ∼126 μm, without experiencing coarsening or variant selection phenomena. The alloy balanced strength and ductility post-heat treatment with a UTS of 1015 MPa and an EL of 16.5% relative to the as-deposited state (UTS of 1199 MPa and EL of 11.9%). Notably, the LCF properties of the heat-treated SLM Ti–5.6Al–3.8V alloy are superior to those of other Ti–6Al–4V alloys produced by additive manufacturing and comparable to traditional forgings. At high strain amplitudes (1–1.5%), the fatigue life of this alloy was twice that of the Ti–6Al–4V forgings. Furthermore, we comprehensively analyzed the microstructure, strength, and ductility of the SLM Ti–5.6Al–3.8V alloy to elucidate the factors influencing its LCF properties. These findings provide a solid foundation for improving the LCF properties of additively manufactured Ti–6Al–4V alloy, thereby contributing to its safe and reliable use in critical applications.

Effects of Wire Electrical Discharge Finishing Cuts on the Surface Integrity of Additively Manufactured Ti6Al4V Alloy.

The Selective laser melting (SLM) technology of recent years allows for building complex-shaped parts with difficult-to-cut materials such as Ti6Al4V alloy. Nevertheless, the surface integrity after SLM is characterized by surface roughness and defects in the microstructure. The use of additional finishing technology, such as machining, laser polishing, or mechanical polishing, is used to achieve desired surface properties. In this study, improving SLM Ti6Al4V alloy surface integrity using wire electrical discharge machining (WEDM) is proposed. The influence of finishing WEDM cuts and the discharge energy on the surface roughness parameters Sa, Svk, Spk, and Sk and the composition of the recast layer were investigated. The proposed finishing technology allows for significant improvement of the surface roughness by up to 88% (from Sa = 6.74 µm to Sa = 0.8 µm). Furthermore, the SEM analyses of surface morphology indicate improving surface integrity properties by removing the balling effect, unmelted particles, and the presence of microcracks. EDS analysis of the recast layer indicated a significant influence of discharge energy and the polarization of the electrode on its composition and thickness. Depending on the used discharge energy and the number of finishing cuts, changes in the composition of the material in the range of 2 to 10 µm were observed.

Effect of Surface Modifications on Surface Roughness of Ti6Al4V Alloy Manufactured by 3D Printing, Casting, and Wrought.

This work aimed to comprehensively evaluate the influence of different surface modifications on the surface roughness of Ti6Al4V alloys produced by selective laser melting (SLM), casting and wrought. The Ti6Al4V surface was treated using blasting with Al2O3 (70-100 µm) and ZrO2 (50-130 µm) particles, acid etching with 0.017 mol/dm3 hydrofluoric acids (HF) for 120 s, and a combination of blasting and acid etching (SLA). It was found that the optimization of the surface roughness of Ti6Al4V parts produced by SLM differs significantly from those produced by casting or wrought processes. Experimental results showed that Ti6Al4V alloys produced by SLM and blasting with Al2O3 followed by HF etching had a higher surface roughness (Ra = 2.043 µm, Rz = 11.742 µm), whereas cast and wrought Ti6Al4V components had surface roughness values of (Ra = 1.466, Rz = 9.428 m) and (Ra = 0.940, Rz = 7.963 m), respectively. For Ti6Al4V parts blasted with ZrO2 and then etched by HF, the wrought Ti6Al4V parts exhibited higher surface roughness (Ra = 1.631 µm, Rz = 10.953 µm) than the SLM Ti6Al4V parts (Ra = 1.336 µm, Rz = 10.353 µm) and the cast Ti6Al4V parts (Ra = 1.075 µm, Rz = 8.904 µm).

Modified material constitutive model with activation energy for machining of selective laser melted Ti6Al4V alloys fabricated by different scanning strategies

The thermally activated mechanisms during machining process have a critical influence on the micromechanical properties of metal materials. Thus, a constitutive model describing the response of flow stress on the activated mechanisms has attracted extensive interest. Considering different laser scanning strategies (0°, 67.5° and 90°) and building directions (top and front surfaces), a modified constitutive model with activation energy effect for machining of selective laser melted (SLMed) Ti6Al4V is proposed on the base of Johnson–Cook model. And a new modified term is introduced to describe the dislocation kinetics mechanisms with thermally activated energy with different laser scanning strategies. Besides, the influence of varied modified coefficient on the flow behavior is also studied in the paper, and the modified coefficient produces important effect on the chip morphology and its segmentation. Milling experiments and simulations of SLMed Ti6Al4V with different scanning strategies have been carried out to verify the accuracy of the modified model. Simulation results show that the proposed model can effectively predict serrated chip characteristic and its formation. In addition, the modified model can well simulate the effect of thermally activated energy on the micromechanical evolution during SLMed Ti6Al4V milling process, which is attractive for the dislocation mechanism research of plastic deformation in the cutting operations.

Manufacturability study in laser powder bed fusion of biomedical Ti alloys for orthopedic implants: an investigation of mechanical properties, process-induced porosity and surface roughness

PurposeSince the biomedical implants with an improved compressive strength, near bone elastic modulus, controlled porosity, and sufficient surface roughness, can assist in long term implantation. Therefore, the fine process tuning plays its crucial role to develop optimal settings to achieve these desired properties. This paper aims to find applications for fine process tuning in laser powder bed fusion of biomedical Ti alloys for load-bearing implants.Design/methodology/approachIn this work, the parametric porosity simulations were initially performed to simulate the process-induced porosity for selective laser-melted Ti6Al4V as per full factorial design. Continually, the experiments were performed to validate the simulation results and perform multiresponse optimization to fine-tune the processing parameters. Three levels of each control variable, namely, laser power – Pl (180, 190, 200) W, scanning speed – Vs (1500, 1600, 1700) mm/s and scan orientation – ϴ{1(0,0), 2(0,67°), 3(0,90°)} were used to investigate the processing performance. The measured properties from this study include compressive yield strength, elastic modulus, process-induced porosity and surface roughness. Finally, confirmatory experiments and comparisons with the already published works were also performed to validate the research results.FindingsThe results of porosity parametric simulation and experiments in selective laser melting of Ti6Al4V were found close to each other with overall porosity (less than 10%). The fine process tuning was resulted in optimal settings [Pl (200 W), Vs (1500 mm/s), ϴ (0,90°)], [Pl (200 W), Vs (1500 mm/s), ϴ (0,67°)], [Pl (200 W), Vs (1500 mm/s), ϴ (0,0)] and [Pl (200 W), Vs (1500 mm/s), ϴ (0,0)] with higher compressive strength (672.78 MPa), near cortical bone elastic modulus (12.932 GPa), process-induced porosity (0.751%) and minimum surface roughness (2.72 µm). The morphology of the selective laser melted (SLMed) surface indicated that the lack of fusion pores was prominent because of low laser energy density among the laser and powder bed. Confirmatory experimentation revealed that an overall percent improvement of around 15% was found between predicted and the experimental values.Originality/valueSince no significant works are available on the collaborative optimization and fine process tuning in laser powder bed fusion of biomedical Ti alloys for different load bearing implants. Therefore, this work involves the comprehensive investigation and multi-objective optimization to determine optimal parametric settings for better mechanical and physical properties. Another novel aspect is the parametric porosity simulation using Ansys Additive to assist in process parameters and their levels selection. As a result, selective laser melted Ti alloys at optimal settings may help in examining the possibility for manufacturing metallic implants for load-bearing applications.

Comparative analysis of tool wear in micro-milling of wrought and selective laser melted Ti6Al4V

The parts produced by additive manufacturing (AM) are not usually appropriate for direct applications and require several post-processing operations. Micro-milling, as a most common post-processing operation in micromachining, is performed considering selective laser melted (SLM) Ti6Al4V as the workpiece under dry condition. The experiments are conducted considering a constant cutting speed and axial depth using a TiAlSiN-coated tungsten carbide end mill of Ø300 μm. It employs two different feed rates considering the size effect imposed by the edge radius of the micro end mill. The micro-milling performances for the SLM Ti6Al4V are compared with the performance for wrought Ti6Al4V. The outcomes, such as tool wear and surface characteristics, are examined for both the materials. Equiaxed grains, exhibiting higher ductile nature of wrought Ti6Al4V, produces adhesive tool wear, BUE formation and poor surface topography at both feed rates. Alternatively, the lamella microstructure of SLM Ti6Al4V, exhibiting relatively high hardness, produces less adhesive tool wear and BUE formation; instead, it generates more abrasion of the tool and hence increases the surface roughness. Quantitatively, the cutting-edge radius enlarges by 18–37% and 10–34% for wrought and SLM Ti6Al4V, respectively. Moreover, the SLM Ti6Al4V shows an 8–10.6% lower average surface roughness value than wrought Ti6Al4V.

Data imputation strategies for process optimization of laser powder bed fusion of Ti6Al4V using machine learning

A database linking process parameters and material properties for additive manufacturing enables the performance of the material to be determined based on the process parameters, which are useful in the design and fabrication stage of a product. The data, however, are often incomplete as each individual research work focused on certain process parameters and material properties due to the wide range of variables available. Imputation of missing data is thus required to complete the material library. In this work, we attempt to collate the data of Ti6Al4V, a popular alloy used in aerospace and biomedical industries, fabricated using powder bed fusion, or commonly known as selective laser melting (SLM). Various imputation techniques of missing data of the SLM Ti6Al4V dataset, such as the k-nearest neighbor (kNN), multivariate imputation by chained equations, and graph imputation neural network (GINN) are investigated in this article. It was observed that kNN performed better in imputing variables related to process parameters, whereas GINN performed better in variables related to material properties. To further improve the quality of imputation, a strategy to use the median of the imputed values obtained from the three models has resulted in significant improvement in terms of the relative mean square error. Self-organizing map was used to visualize the relationship among the process parameters and the material properties.

Research on the Cutting Force and Serrated Chips in Ultra-Precision Micro-Grooving of SLM Ti6Al4V Alloy.

Selective laser melting (SLM) has significant advantages in the near net shape manufacturing of metal parts with complex geometries. However, SLM parts usually have problems such as poor surface quality and low dimensional accuracy, which require post-processing. This paper focuses on the research around the influence of ultra-precision micro-grooving the SLM Ti6Al4V alloy on the cutting force and serrated chips. The influence of the processing parameters on the cutting force and surface processing quality was analyzed in detail, and the cutting simulation model of the SLM Ti6Al4V alloy was established. The formation process of the serrated chip was successfully simulated, and the experiments verified the reliability of the established model. The research results show that the dynamic cutting force and surface processing quality are mainly related to the depth of cut, and the two trends are consistent. It is also shown that the serrated chip begins on the free surface of the workpiece and propagates deeply in the shear zone, forming a shear band, and its serrated nodules move upward and forward to form periodic serrated chips.

Corrosion Performances of Selective Laser Melting Ti6Al4V Alloy in Different Solutions

Selective laser melting (SLM) can fabricate titanium and its alloy components with both elaborate internal architectures and complex shapes without geometric constrictions. The corrosion resistance of SLM-produced Ti and its alloy is crucial in some applications such as marine and biomedical environments. Here, potentiodynamic polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion behaviors of SLM-produced Ti-6Al-4V in the four corrosive media (simulated body fluid (SBF), phosphate buffered saline solutions (PBS), 3.5 wt.% NaCl aqueous solution, 15 wt.% NaCl aqueous solution). The relevant results demonstrate the inferior corrosion resistance of the SLM-produced Ti-6Al-4V sheet compared with the commercial casting Ti-6Al-4V sheet in the four solutions. The corrosive current density of SLM-produced Ti-6Al-4V in PBS solution is 1.78 μA cm−2 and 7.065 μA cm−2 in 15 wt.% NaCl solution, and the values of charge transfer resistance for SLM-produced Ti-6Al-4V in the four solutions are in the order: 17.9 kΩ cm−2 (in 15 wt.% NaCl) < 25.2 kΩ cm−2 (in 3.5 wt.% NaCl) < 28.1 kΩ cm−2 (in SBF) < 39.8 kΩ cm−2 (in PBS), demonstrating the best protective performance of the passivation film on the SLM-produced Ti-6Al-4V sheet in PBS.

On study of process induced defects-based fatigue performance of additively manufactured Ti6Al4V alloy

Additively manufactured Ti6Al4V are high strength alloys but associated with inferior ductility and inherent defects. These process-induced defects act as a stress raiser and deteriorates the mechanical and fatigue properties of the alloy. Post-processing is generally done to enhance the ductility and fatigue properties but at the expense of strength of the additively manufactured Ti6Al4V alloy. In this study, the effect of defects on mechanical properties and fatigue performance of additively manufactured (selective laser melting) Ti6Al4V alloy has been investigated based on experimentally calibrated defects-based model. The as-built specimens were subjected to different heat treatments in order to optimize their mechanical properties and the most optimum heat treatment was then selected for investigation of changes in fatigue properties. The beneficial effect of heat treatment on mechanical properties was mainly associated with the reduction in fraction of α ’-martensitic microstructure and increase in α -lamellae thickness. Most of the fatigue failures occurred from surface and sub-surface defects, owing to the high stress concentration factor associated with them, and improved fatigue lives as a result of optimum heat treatment. A process-structure–property (PSP) linkage has been established to predict the mechanical properties. Experimentally calibrated defects’ based fatigue model has been formulated to predict the fatigue performance using the experimentally observed data i.e. the process induced defects’ size and their locations. • Different post-processing of SLM-based AM Ti6Al4V was investigated. • Heat treatment was carried out, which improved both mechanical & fatigue properties. • A Process-Structure-Property (PSP) linkage was established. • A new defects-based model was proposed to predict the fatigue properties.

Measurement and analysis of tool wear and surface characteristics in micro turning of SLM Ti6Al4V and wrought Ti6Al4V

Parts produced using additive manufacturing (AM) have a significant transition in the features such as surface quality, residual stresses, microhardness, etc. To make the AM component suitable for an application, post-processing of the parts is required to remove the non-desirable features. In this regard, the micro turning of selective laser melted (SLM) Ti6Al4V are conducted to examine the surface characteristics, tool wear and chip morphology. The results obtained for SLM Ti6Al4V are compared with the results of wrought Ti6Al4V. Attributed to the higher strength and hardness, the SLM Ti6Al4V shows a higher tool wear and surface roughness than the wrought Ti6Al4V. The main tool wear mechanisms involved are built-up edge formation, adhesion, abrasion, and edge chipping for both the materials. The surface roughness is found increased with increasing cutting speed and feed. The wrought Ti6Al4V shows less feed marks and chip adhesion compared to SLM Ti6Al4V. Moreover, the materials side flow is observed in SLM Ti6Al4V only. The chips produced are long and continuous for wrought Ti6Al4V, whereas they are discontinuous for SLM Ti6Al4V. Morphology of the chips shows that they are of scaly structure for SLM Ti6Al4V for all the parameters, whereas they are of lamella structure for wrought Ti6Al4V, particularly at low feed and cutting speed.