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Nanosecond Pulsed Laser Irradiation of Titanium Alloy Substrate: Effects of Periodic Patterned Topography on the Optical Properties of Colorizing Surfaces
摘要： Most of the current works based on surface treatments of metals by laser marking technology are focused on the modification of the color tonality of flat surfaces, or the development of specific topography features, but the combination of both processes is not usually evaluated, mainly due to the complexity of controlling the optical properties on rough surfaces. This research presents an analysis of the influence of the micro-geometrical characteristics of periodic patterned laser tracks on the chromaticity and reflectance of Ti6Al4V substrates. The samples were irradiated with an infrared nanosecond pulsed laser in air atmosphere, taking as the control parameter the scan speed of the beam. A roughness evaluation, microscopic inspection, and absorption and chromaticity examination were conducted. Although micro-crack growth was detected in an isolated case (10 mm/s), the possibility of adjusting the result color was demonstrated by controlling the heat-affected zone thickness of the textures. The results of rough/colored combined textures allow new perspectives in industrial design to open, particularly in aesthetic applications with special properties.
关键词： titanium,oxidation,reflectance,roughness,color,laser marking
更新于2025-09-12 10:27:22
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Process planning guidelines in selective laser melting for the manufacturing of stainless steel parts
摘要： Selective laser melting (SLM) is now, one of the most widespread Additive Manufacturing processes, due to presence in the market and known capabilities for the fabrication of mechanical components, with acceptable levels in geometrical accuracy, surface quality and mechanical properties. However, the metalworking industry is still skeptical for its full adoption in realistic production schemes, because of the lack of non-scholarly knowledge for calibrating process parameters among other technical barriers. In this work, several process planning guidelines are presented as a result of a SLM process calibration for a selected material (stainless steel 316L), with the intention of contributing in process parameters selection in net shape manufacturing. In order to conceive a proper set of guidelines for selective laser melting set up, several parameters were taken into account such as point distance, hatch distance, exposure time among others, with the aim of obtaining appropriate surface quality and good mechanical tensile behavior. Parts were obtained with good surface quality, presenting stable and well-defined weld lines and low presence of partially sintered particles adhered to the surface. After the application of the methodology, top and lateral surface roughness were improved, reaching values of Ra 5.81 and 9.61 μm respectively. In addition, good mechanical properties were obtained, of up to 500 MPa of ultimate tensile strength and 400 MPa of yield stress, comparable to the properties of sintered stainless steels alloys studied in previous works.
关键词： powder bed laser melting,roughness,surface quality,process planning,selective laser melting
更新于2025-09-12 10:27:22
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Helical milling of bore holes in Ti6Al4V parts produced by selective laser melting with simultaneous support structure removal
摘要： Selective Laser Melting (SLM) is a powder bed based Additive Manufacturing (AM) process that is currently being established in the series production of Ti6Al4V components in the aviation industry. One advantage is the significantly lower Buy-to-Fly ratio. However, subsequent machining is necessary in order to remove support structures of the SLM process and to fulfill quality requirements. Experimental results on support structure removal and simultaneous finishing of holes by helical milling are presented. Engagement conditions in helical milling are strongly influenced by the support structure. Material removal rates in both peripheral and axial direction are calculated and agree well with the variation of measured forces in these directions. In addition, the surface roughness of the machined holes is affected by the support structure design and may change along the hole perimeter. The findings indicate how support structures should be designed in order to obtain high quality bore holes in one machining step.
关键词： titanium,helical milling,support structure removal,modeling,force,surface roughness,SLM
更新于2025-09-12 10:27:22
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Study the Effect of Changing the Surface Roughness and the Laser Focus Distance to the Aluminum Appearance using Picosecond Laser
摘要： Picosecond laser device is used to treat Aluminum samples, the appearance of the treated samples is affected by the variation of laser focus distance and the samples surface roughness. Samples with smoother surface before laser treatments show dark colors and high increase in surface roughness after laser treatments, while samples with rougher surfaces before laser treatments show brighter colors with slightly change in surface roughness after the laser treatments. The surface texture, topography, and roughness of the treated samples is characterized to identify the mechanism driving appearance change. The characterization results indicate that size and shape of laser processing induced microscale cavities on the surface may account for the differences in samples appearance.
关键词： Aluminum Appearance,Picosecond Laser,Focus Distance,Surface Roughness
更新于2025-09-12 10:27:22
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Effect of initial surface topography during laser polishing process: Statistical analysis
摘要： Surface finish is one of the most important quality characteristics of fabricated components. Laser polishing (LP) is one of the advanced manufacturing surface finishing techniques that has been recently developed and successfully employed for improving surface quality without deteriorating the overall structural form through surface smoothing by melting and redistributing a thin layer of molten material. This paper advances the statistical analysis of the LP process emphasizing aspects of the effect of the initial surface topography. Flat and ground initial surfaces are used for comparative statistical analysis of initial and polished profiles obtained experimentally. Their profile geometries and surface quality characteristics, such as, roughness, were compared and analyzed. In addition, LP process was experimentally investigated as a thermodynamic operator represented by a transfer function and it was examined by means of a coherence function.
关键词： statistical analysis,initial topography,Laser polishing,travel speed,laser power,surface quality,roughness
更新于2025-09-12 10:27:22
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Wear Tribo-Performances of Laser Cladding Colmonoy-6 and Stellite-6 Micron Layers on Stainless Steel 304 Using Yb:YAG Disk Laser
摘要： Stainless steel material has been widely used in aeronautical, chemical and nuclear industries due to good corrosion resistance. However, the material has less hardness and wear resistance. In this study, two various depositions namely Colmonoy-6 and Stellite-6 have produced on 304 Stainless steel. Besides, the coating was examined to reveal their metallurgical, mechanical and tribological properties. In addition, wear mechanism, wear debris and roughness averages were studied. The outcomes indicate that both coatings show with dendrite structure due to rapid cooling rates. Hardness of the clad surface has improved than substrate material. The results of friction coefficient of specimen with Colmonoy-6 is lower than that of specimens Stellite-6 and substrate. Also, wear resistance of Colmonoy-6 has increased 49 times than substrate sample, which reveals that Colmonoy-6 laser cladding plays role on wear resistance. Adhesive and abrasive are the major wear mechanisms in the present study.
关键词： Wear debris,Microstructure,Stainless steel 304,Roughness,Wear performance,XRD,Laser cladding,Hardness
更新于2025-09-12 10:27:22
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Cr12MoV Die Repair Experiment Based on Laser Cladding with Wire
摘要： In this paper, SKD11 steel wire has been deposited on Cr12MoV plate using Nd: YAG pulsed laser for repairing the die surface damage. The effects of laser power, wire feeding speed, scanning speed and surface roughness on clad geometry have been studied with OM and LSCM. hardness distribution of the cladding layer is also obtained by microhardness tester. Experiment results indicate that the surface roughness is important for clad characteristics due to the light trapping effect. With the increases of roughness, the laser absorption ratio can be raised, both the clad depth and the dilution rate increase, the height decreases. The essence of influence mechanism is effective body energy Ev and specific filling rate ω, and can be used as critical process factors. When Ev is 80~100 J/mm3 and ω is 1~3, a flat cladding layer can be obtained with low dilution, less fusion defects and high hardness.
关键词： laser cladding with wire,clad geometry,hardness,Cr12MoV,surface roughness
更新于2025-09-12 10:27:22
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Characterization and tribological evaluation of NiCrMoNb and NiCrBSiC laser cladding on near-α titanium alloy
摘要： In the present study, two different types of coatings such as NiCrMoNb and NiCrBSiC were produced on titanium alloy using a high power Yb:YAG disk laser. Then the coatings were analysed to expose their phase characterization, microstructure and hardness using X-ray diffraction analysis (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), optical microscopy (OM) and Vickers microhardness machine (HV). Further, tribotest was performed through ball-on-plate machine to analyse the wear properties of coatings. In addition, worn surfaces of cladding and surface roughness were examined using FE-SEM and whitelight interferometer, respectively. The results showed that the both NiCrMoNb and NiCrBSiC cladding exhibited a dendrite homogeneous structure due to higher cooling rates. XRD results indicating that the solid solution of γ-Ni was mixed with chromium, boride, silicon and formed the structure of interdendritic eutectics on cladding region. Microhardness of the clad layer has remarkably been increased than substrate. The results of friction coefficient of specimen with NiCrBSiC are lower than that of specimens NiCrMoNb clad and substrate. Also, the wear resistance of NiCrBSiC clad has been increased than NiCrMoNb clad and substrate sample, which reveals that NiCrBSiC laser cladding plays a major role on wear resistance. The microstructures of NiCrMoNb and NiCrBSiC cladding layer are composed of Ni-rich austenitic, Cr, Mo, Nb and carbide, borides, respectively. The analysed wear track indicates that adhesion and abrasion was a major wear mechanism. The NiCrSiBC cladded worn-out surfaces exhibited reduction in surface roughness than NiCrMoNb clad and substrate.
关键词： NiCrBSiC,Cladding,Microstructure,Titanium alloy,Surface roughness,Wear mechanism,NiCrMoNb
更新于2025-09-12 10:27:22
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Control of short-pulsed laser induced periodic surface structures with machining -picosecond laser nanotexturing with magnetic abrasive finishing-
摘要： An active area of research is the altering of surface functions (e.g., wettability and cell adhesion) by controlling fine surface structures such as laser-induced periodic surface structures (LIPSS). It has been found that micrometer-scale grooving (produced, for example, using ultraprecision cutting) followed by short-pulsed laser irradiation can result in efficient LIPSS coverage of a large area. However, micrometer-scale grooves can remain on the surface after short-pulsed laser irradiation. In this paper, to clarify the phenomenon and processing principle of groove-assisted short-pulsed laser irradiation, a finite-difference time-domain simulation is developed and experiments are conducted using 304 stainless steel and nickel-phosphorus (Ni–P) plating layer substrates. The use of magnetic abrasive finishing (MAF) is proposed for fabricating sub-micrometer-deep straight grooves with various peak-to-peak distances (pitch length) prior to the short-pulsed-laser irradiation. The subsequent short-pulsed-laser irradiation produces sub-micrometer-deep straight structures superimposed on the MAF-produced surface. While the pattern and depth of LIPSS are influenced by the groove depth made by MAF prior to the short-pulsed laser irradiation, the pitch length of LIPSS is dependent on the laser wavelength. This demonstrates the ability of MAF to produce grooves that guide the LIPSS and the efficacy of the developed method for fabricating fine LIPSS. The geometry of the sub-micrometer deep grooves—made prior to the short-pulsed laser irradiation—is the dominant factor in determining the pattern and geometry of the LIPSS.
关键词： Straight sub-micrometer groove,Surface roughness,Magnetic abrasive finishing,Short-pulsed laser
更新于2025-09-12 10:27:22
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Prediction of surface roughness and material removal rate in laser assisted turning of aluminium oxide using fuzzy logic
摘要： Processing of ceramics with good surface integrity and high material removal rate is a challenging task in the manufacturing industry. Laser assisted machining (LAM) is one of the benchmark technique currently used in industry to process difficult to machine materials. In LAM, laser is used as source to heat the work piece and simultaneously remove the softened material by cutting tool without changing the material microstructure. Since many process parameters are involved in LAM, experimental investigation of processing of ceramics is expensive. So the main objective of this present work is to develop an Artificial Intelligence model to understand the process mechanics and for the prediction of surface roughness and material removal rate (MRR) during laser assisted turning of Aluminium oxide using fuzzy logic. Input parameters are assumed as triangular and Gaussian function and output parameters are assumed as trapezoidal function. It is inferred that increase in cutting speed and pulsed frequency of laser, there is an improvement in surface finish, whereas increase of feed rate results in deterioration of surface integrity. The material removal rate is directly proportional to feed, speed, depth of cut and pulsed frequency of laser. There is a better agreement between experimental and fuzzy model values. The proposed model predicts the surface roughness and MRR with prediction error of 15.76 and 7.69 % respectively.
关键词： material removal rate,Laser assisted machining,fuzzy logic,surface roughness,Ceramics
更新于2025-09-12 10:27:22