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Magnetic-Field-Induced Partial-to-Full Penetration Evolution and Its Mechanism During Laser Welding
摘要： The geometry and tensile strength of magnetic-?eld-assisted laser-welded Ti-6Al-4V joints have been studied. Due to the effects of the magnetic ?eld on the melt ?ow behavior during welding, the weld penetration depth increased from 4.27 mm (partial penetration) to 5.00 mm (full penetration) and the curvature of the weld cross-section decreased, improving the weld tensile strength. The fusion zone was enlarged, showing a maximum increase of 53.4% in area when the magnetic ?eld intensity was 90 mT. The increased penetration depth and fusion zone area suggest that application of a magnetic ?eld can improve the energy utilization of the laser during laser butt welding. The mechanism of the magnetic-?eld-induced penetration depth evolution is discussed. This study provides a new energy-saving method to obtain a full-penetration weld using laser welding at lower power.
关键词： Magnetic-field-assisted laser welding,Tensile strength,Energy utilization,Ti-6Al-4V,Weld geometry
更新于2025-11-28 14:24:20
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The effect of build orientation on the microstructure and properties of selective laser melting Ti-6Al-4V for removable partial denture clasps
摘要： Statement of problem. Selective laser melting (SLM) Ti-6Al-4V has been used for removable partial dentures, but the impact of SLM Ti-6Al-4V build orientation is not evident. Purpose. The purpose of this in vitro study was to investigate the microstructure and properties of SLM Ti-6Al-4V clasps with different build orientations compared with cast Ti-6Al-4V clasps. Material and methods. Forty-eight clasps were made from Ti-6Al-4V alloys by SLM with 3 different build orientations (SLM0, SLM45, and SLM90) and cast (CAST) as a control. The microstructure was investigated by using a metallographic microscope and a confocal laser scanning microscope. The fit and surface roughness of the clasps were measured, and the physical properties were evaluated. In addition, the von Mises stresses in the clasps were calculated by finite element analysis. All specimens were then subjected to insertion and removal tests in artificial saliva to model 5 years of clinical use. After these tests, 3-point bend tests were used to analyze the fracture surface of the clasp arms, which were observed by using a scanning electron microscope. All data were statistically analyzed (a=.05). Results. The microstructure of the Ti-6Al-4V specimens was a comixture of a+b phases. In addition, growth directions of b grains were approximately parallel to the build orientation, with acicular a grains present between b grains. SLM0 and SLM45 had significantly higher roughness than SLM90. Even though the fit was inferior to that of SLM90, SLM0 and SLM45 still performed better than cast specimens (P<.05). The finite element analysis showed that the maximum von Mises stress was located on the middle part of the retainer arms and that the values of the 0.50-mm undercut clasps were much lower than the elastic limit. In addition, the decrease of retentive force in SLM90 clasps was less than that of the CAST group (P<.05). CAST clasps showed brittle fracture, whereas all SLM clasps showed ductile fracture. Conclusions. The microstructure of SLM Ti-6Al-4V affected the properties of clasps by changing the anisotropy of specimens. Among the tested groups, SLM90 clasps had the best fit, the lowest surface roughness, and the best fatigue resistance. Furthermore, SLM Ti-6Al-4V clasps could be engaged into 0.50-mm undercuts.
关键词： Selective laser melting,Ti-6Al-4V,build orientation,removable partial denture clasps,properties,microstructure
更新于2025-11-21 11:08:12
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Corrosion study of laser cladded Ti-6Al-4V alloy in different corrosive environments
摘要： Laser cladding of Ti-6Al-4V powder on a substrate with the same chemical composition was performed at different laser powers. The effect of laser power on the microstructure and corrosion behavior was then investigated. Electrochemical studies were performed by potentiodynamic polarization tests in different corrosive environments (3.5% NaCl, 2% H2SO4 and 5% HCl solutions). Microstructural investigation together with phase characterization revealed that laser cladded Ti-6Al-4V coatings were composed of needle-like martensite (ɑ/) and coaxial hexagonal compact (ɑ) phases. The coatings were crack-free; however, some cavities were observed in the coatings produced at high laser powers. In all three corrosive environments, the coatings showed a more noble corrosion behavior compared to the untreated substrate. The results showed that corrosion potential increases from ?410 (mV) to ?130 (mV) in NaCl and from ?50 (mV) to ?20 (mV) in H2SO4 enviroments but decreases from ?60 (mV) to ?270 (mV) in HCl solution. Increasing laser power had a positive effect on the corrosion behavior in NaCl and H2SO4 solutions; however, it had a negative effect on the corrosion behavior in HCl solution.
关键词： Corrosion,Laser cladding,Ti-6Al-4V alloy,Microstructure
更新于2025-09-23 15:23:52
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Effects of Nd:YAG laser surface treatment on tribological properties of cold sprayed Ti-6Al-4V coatings tested against 100Cr6 steel under dry condition
摘要： The surfaces of cold sprayed Ti-6Al-4V (Ti64) coatings were laser irradiated with different laser powers of 50-200 W to study the effects of Nd:YAG laser surface treatment on their tribological properties. The hardness of the laser treated Ti64 coatings became higher with higher laser power due to the more rapid cooling caused by a larger temperature difference between the coating surface and room temperature. The wear of the laser treated Ti64 coatings tested against 100Cr6 steel balls under dry condition at room temperature decreased with increased laser power as a result of their increased surface wear resistance associated with their increased surface hardness. It could be concluded that the laser surface treatment of the cold sprayed Ti64 coatings improved their surface wear resistance compared to that of the untreated Ti64 coatings.
关键词： Ti-6Al-4V,laser power,hardness,wear,laser surface melting,Cold spray
更新于2025-09-23 15:23:52
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Influence of Si Coating on Interfacial Microstructure of Laser Joining of Titanium and Aluminium Alloys
摘要： A common phenomenon in the dissimilar joints is the presence of brittle compounds in the joining interface region. The brittle phases can decrease by introduction of interlayers in the joining interface, such as silicon, that inhibits the formation of Al3Ti and AlTi3 phases in joining process between titanium and aluminium alloys. In the present work, the joining of titanium and aluminium alloys have been carried out using a Yb:fiber laser, considering the prior silicon film deposited on titanium alloy interface by DC magnetron sputtering. Butt joint conditions were maintained constant: laser average power, process speed and beam positioning along the interface joining toward aluminium alloy (1200 W, 3.0 m/min and 0.3 mm, respectively). Metallographic analyses were carried out on the cross-section joint by optical and electronic microscopies. When the melted aluminium alloy wet the solid-state titanium alloy, a more restrict compound layer was formed in the joining interface. EDS line scanning in the joining interface showed a reduction of compound layer thickness, considering the silicon as interlayer, reaching the mean value of 3 μm, i.e., up to five times thinner if compared to joining without silicon during the process.
关键词： AA6013,Ti-6Al-4V,dissimilar metals,joining process
更新于2025-09-23 15:22:29
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A comparative study of laser metal deposited and forged Ti-6Al-4V alloy: Uniaxial mechanical response and vibration fatigue properties
摘要： This paper conducts a comparative study on mechanical properties of LMD and forged Ti-6Al-4V, focusing on uniaxial compression, tension and shear response with different strain rates, and vibration fatigue behaviors with 45–50 Hz in frequency. The micro-observation on initial microstructures and fractures explains the mechanism of lower uniaxial strength, shorter fatigue life, and larger dispersion in fatigue life and fracture position of LMD sample compared with the forged counterpart. Initial void defects within LMD sample tend to be stress-concentration zone, further initiating fatigue cracks. The columnar β grains leads to anisotropy of fatigue life and crack propagation for LMD sample.
关键词： Fracture analysis,Laser metal deposition,Vibration fatigue,Initial defect,Ti-6Al-4V
更新于2025-09-23 15:21:01
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Effect of Scanning Strategy During Selective Laser Melting on Surface Topography, Porosity, and Microstructure of Additively Manufactured Ti-6Al-4V
摘要： The effect of the scanning strategy during selective laser melting (SLM) of Ti-6Al-4V was investigated. An optimized cellular scan strategy (island scan modeled) was compared to a simple cellular scan strategy (island scan stripes) and a simple antiparallel line scanning strategy (line scan). Surface texture was investigated by optical three-dimensional (3D) surface measurements, which when combined with light optical microscopy (LOM), revealed deflections caused by the thermal stresses during the build process. Elevated edges caused by the edge-effect dominate the surface texture of all investigated specimens. The scanning strategy determines the surface texture, and the lowest surface roughness was obtained by the line scan strategy. Porosity was investigated with X-ray computed tomography-imaging. Mainly spherical porosity was observed for the line scan and island scan modeled specimens, while the island scan stripes strategy showed more lack-of-fusion defects and a higher total porosity amount. Microstructure was investigated with LOM and scanning electron microscopy (SEM). The microstructure in Ti-6Al-4V was largely martensitic α’ and prior β grains. The morphology is different for the various scan strategies, and decomposition of α’ into lamellar α/β was observed in the bottom part of the island scan specimen. Accordingly, the hardness decreased in the decomposed part of the specimen.
关键词： scanning strategy,porosity,surface topography,selective laser melting,powder bed fusion,microstructure,SLM,Ti-6Al-4V
更新于2025-09-23 15:21:01
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Experimental and numerical investigation of selective laser meltinga??induced defects in Tia??6Ala??4V octet truss lattice material: the role of material microstructure and morphological variations
摘要： The remarkable progress in additive manufacturing has promoted the design of architected materials with mechanical properties that go beyond those of conventional solids. Their realization, however, leads to architectures with process-induced defects that can jeopardize mechanical and functional performance. In this work, we investigate experimentally and numerically as-manufactured defects in Ti–6Al–4V octet truss lattice materials fabricated with selective laser melting. Four sets of as-manufactured defects, including surface, microstructural, morphological, and material property imperfections, are characterized experimentally at given locations and orientations. Within the characterized defects, material property and morphological defects are quanti?ed statistically using a combination of atomic force microscopy and micro–computed tomography to generate representative models that incorporate individual defects and their combination. The models are used to assess the sensitivity to as-manufactured defects. Then, the study is expanded by tuning defects amplitude to elucidate the role of the magnitude of as-designed defects on the mechanical properties of the lattice material.
关键词： mechanical properties,octet truss lattice,additive manufacturing,defects,Ti–6Al–4V,selective laser melting
更新于2025-09-23 15:21:01
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Prediction of the deformation behavior of a selective laser-melted Ti-6Al-4V alloy as a function of process parameters
摘要： Recent studies have shown that the mechanical properties of Ti alloys produced by additive manufacturing (AM) methods are sensitive to AM process parameters. The mechanical threshold stress (MTS) model is capable of predicting the flow stress behavior of materials; however, the parameters needed in the MTS model are affected by the microstructure that originates from the AM process parameters. To find a relationship between the AM process parameters and the MTS parameters, the effect of process parameters on the mechanical properties of selective laser-melted (SLM) Ti-6Al-4V samples was studied. As the MTS model is sensitive to the microstructure, only near fully dense samples were considered.
关键词： Selective laser method,Ti-6Al-4V,Deformation behavior,Additive manufacturing
更新于2025-09-23 15:21:01
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Connecting Diffraction-Based Strain with Macroscopic Stresses in Laser Powder Bed Fused Ti-6Al-4V
摘要： The laser powder bed fusion (LPBF) production process often results in large residual stress (RS) in the parts. Nondestructive techniques to determine RS are badly needed. However, a reliable quantification of macro-RS (i.e., stress at the component level) by means of diffraction-based techniques is still a great challenge, because the link between diffraction-based strain and macro-RS is not trivial. In this study, we experimentally determine (by means of in-situ synchrotron radiation diffraction) this link for LPBF Ti-6Al-4V. We compare our results with commonly used models to determine the so-called diffraction elastic constants (DECs). We show that LPBF materials possess different DECs than wrought alloys, simply because their microstructural and mechanical properties are different. We also show that the existing models can be used to calculate DECs only if high accuracy of the RS values is not required. If the peculiarities of the microstructure have to be taken into account (as is the case of additively manufactured materials), a radically new approach is desirable.
关键词： synchrotron radiation diffraction,Laser powder bed fusion,residual stress,Ti-6Al-4V,diffraction elastic constants
更新于2025-09-23 15:21:01