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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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As-fabricated surface morphologies of Ti-6Al-4V samples fabricated by different laser processing parameters in selective laser melting
摘要： The surface morphology of a product plays a crucial role under mechanical loading and chemical environment. Surfaces of Selective Laser Melting (SLM) products often contain high roughness, which varies in different planes as well. The authors have explored the surface characteristics of the SLM samples that are influenced by different combinations of laser processing parameters. The considered processing parameters were Energy Density (ED) and its technological parameters namely laser power, scanning speed and hatch spacing. Additionally, a comparison study has been executed by rescanning effects considering melting with low ED and, thereafter, re-scanning by the best possible laser processing parameters. The results evidently showed that the surface morphologies differ significantly due to different laser processing parameters. Eventually, the thermal and physical behavior of materials, such as the viscosity of the melt pool, thermal and physical stability of the melt pool, solidification time, cooling time, shrinkage, capillary effect, surface tension, balling effect, and the amount of melting of a powder particle, influenced the surface properties of the samples, along with unpredictability. The results showed an interesting correlation between the processing parameters and the occurrence of microcracks on the vertical walls of the specimens caused by the partially melted adhered powder particles.
关键词： Ti-6Al-4V alloy,Selective laser melting,Laser processing parameters,Surface morphology,Rescanning
更新于2025-09-23 15:19:57
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Underwater wire-feed laser deposition of the Ti–6Al–4V titanium alloy
摘要： Underwater wire-feed laser deposition (UWLD) of the Ti-6Al-4V alloy was firstly carried out utilizing a laser deposition nozzle, and the deposition appearance, geometry characteristics, microstructure and microhardness of deposited tracks were studied. At a lower gas flow rate, the absorption of residual water and scattering of aerosol particles on laser beam caused UWLD instability and decreased molten metal wettability. Upon increasing the gas flow rate, the aerosol particle density decreased, increasing the laser density and decreasing the cooling rate of molten metal; thus, the height and deposition angle of UWLD track decreased as the corresponding width and fusion depth increased. The microstructures of the deposited metal at a gas flow rate of 10 L/min were composed of the coarse lath α phase in upper region and the acicular martensite α′ with different size scales in middle and bottom regions. With increasing the gas flow rate to 20 L/min, the microstructure was primarily acicular martensite along with a small amount of α phase, and the martensite exhibited a larger grain size and stronger texture. At a gas flow rate of 20 L/min, the deposited process was stable and uniform deposition track without oxidation layer was obtained for UWLD Ti-6Al-4V alloy.
关键词： Ti-6Al-4V alloy,Laser propagation mechanism,Microstructure,Microhardness,Underwater wire-based laser deposition,Geometrical characteristics
更新于2025-09-19 17:13:59
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Distribution of Al Element of Ti–6Al–4V Joints by Fiber Laser Welding
摘要： In the process of laser welding, the uneven distribution of solute elements caused by element burning loss and ?ow of molten pool a?ects the quality of joints. In this paper, butt welding experiments were conducted on the 3 mm thick Ti–6Al–4V specimens with di?erent preset ratios of Al and Si powders by using 4 kW ?ber laser. The distribution of Al solute element and its in?uence on the microstructure and mechanical properties of the ?nal weld joint were investigated. The results showed that the self-di?usion of Al element and the ?ow of molten pool a?ects the alloy elements distribution in laser welding. And the microhardness of the welded joint with Ti–6Al–4V and 90% Al + 10% Si powders was signi?cantly higher than that with only Ti–6Al–4V, with the di?erence of about 130HV. At the same time, in the joint with 90% Al and 10% Si powders, the acicular α’ size was ?ner, and basketweave microstructure was present as well. This research is helpful to better understand the distribution of Al solute element and its in?uence on the joint quality during laser welding of Ti–6Al–4V alloy, which provides a certain reference for improving the weld or surface properties of Ti–6Al–4V alloy during laser processing.
关键词： Ti–6Al–4V alloy,structure morphology,laser welding,elements distribution,microhardness
更新于2025-09-16 10:30:52
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Structure and Phase Composition of Ti-6Al-4V Samples Produced by Direct Laser Deposition
摘要： In this article had been carried out X-ray phase analysis of the samples obtained using direct laser deposition. Two groups of samples were studied: the first one was obtained with oscillation of laser radiation, the second one – without. The investigations have shown that in the process of direct laser deposition, the α+β phase is formed from a Ti-6Al-4V titanium alloy with oscillation of laser radiation.
关键词： high-speed direct laser deposition,titanium alloys,X-ray analysis,oscillations of laser radiation,Ti-6Al-4V alloy,microstructure
更新于2025-09-16 10:30:52
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Influence of laser post-processing on pore evolution of Ti–6Al–4V alloy by laser powder bed fusion
摘要： In laser powder bed fusion (LPBF) processes, critical defect issues such as porosity limit the quality of the fabricated part. This work investigates the mechanism of pore evolution during the laser post-processing of an LPBF part. A laser beam was utilized to scan the top surface of a Ti–6Al–4V alloy part. The morphologies of the internal layers as well as the distribution of the porosity inside the Ti–6Al–4V sample were experimentally measured and compared using micro-computed tomography (micro-CT). It was found that the void fraction was significantly decreased, from 2.51% to 0.77%, by laser post-processing. A multi-physics coupled finite element model based on the Level-set method was built to analyze the evolution mechanism of the pore. This model simulated the effects of the energy density, Marangoni flow and mass transfer on the pore evolution. Typical processes were studied in detail, and a table summarizing the pore evolution under different post-processing parameters is given.
关键词： Ti–6Al–4V alloy,Laser powder bed fusion,Pore evolution,Additive manufacturing,Level-set method
更新于2025-09-12 10:27:22
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Improving impact wear resistance of Ti-6Al-4V alloy treated by laser shock peening
摘要： The effects of laser shock peening (LSP) on the impact wear behavior of Ti?6Al?4V alloys were investigated by a homemade impact wear test rig. The microstructure and mechanical properties of the peened samples were studied. During the impact wear test, the energy absorption, impact force, wear contact time and wear mechanism of all the test samples were investigated in terms of the influence of the impact kinetic energy. The results showed that microhardness, elastic modulus and residual compressive stress of the treated samples were markedly improved. The wear resistances of both treated samples were highly improved after LSP, and a higher pulse energy corresponded to a more obvious effect. Besides, the wear in all test samples involved a combination of abrasive and oxidation wear and fatigue spalling.
关键词： laser shock peening,wear mechanism,impact wear,impact kinetic energy,Ti?6Al?4V alloy
更新于2025-09-12 10:27:22
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Effects of laser surface texturing on tribological properties of Ti-6Al-4V in hydroxyethyl-cellulose water-based lubrication
摘要： Purpose – This paper aims to investigate the effect of laser surface texturing on the tribological performance of Ti-6Al-4V disks sliding against Si3N4 balls under hydroxyethyl-cellulose water-based lubrication. The friction coefficients and wear losses of textured and untextured disks were measured and compared. The results indicate that the texture patterns can lead to reduction of friction and wear in the condition of water-based lubrication. Design/methodology/approach – Solutions of hydroxyethyl cellulose were used as water-based lubricants. To find the optimal laser texturing parameters for the best performance enhancement, three line-like patterns were fabricated onto the disks and three machining parameters were used for each type of pattern. Tribological tests were conducted in rotation sliding with ball-on-disk contact configuration on UMT-2. Findings – A higher density of texture lines leads to a larger friction and wear reduction. Compared with untextured disks, the friction coefficient is reduced from 0.043 to 0.028 for textured disks. Some unworn parts were detected in the contact region of the balls against textured disks, which were not found on the balls against untextured disks. The worn surfaces indicated that periodic geometry of the contact track was rebuilt during run-in period, which was beneficial for the formation of lubricant films. Originality/value – In this work, laser surface texturing was used to reduce the friction and wear of Ti-6Al-4V specimens in water-based lubrication, which can be used to improve the tribological performance of Ti-6Al-4V components in mechanical equipment.
关键词： Ti-6Al-4V alloy,Hydroxyethyl-cellulose,Friction reduction,Laser surface texturing,Water-based lubrication
更新于2025-09-09 09:28:46