Influence Of Laser Scanning Speed Research Articles

Influence of Processing Parameters on Laser-Assisted Reactive Sintering of a Mixture of Ni and Ti Powders

Additive manufacturing (AM) plays a crucial role in the development of NiTi alloys, enabling the creation of complex and customized structures while optimizing properties for various biomedical and industrial applications. The aim of this paper was to investigate the influence of laser scanning speed on laser-assisted reactive sintering of a mixture of No and Ti powders. The samples were sintered at two different beam speeds, 4 and 5 4 mm/s and their morphological and microstructural characteristics were investigated. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD) analyses revealed the presence of intermetallic compounds rich in Ni and Ti for both scanning speeds; however, the scanning speed of 5 mm/s produced a microstructure with greater porosity, leading to a sintered body with poorer consolidation. Thus, employing a slower beam scanning of 4 mm/s seems to be a better alternative in the laser-assisted reactive sintering of NiTi alloys.

Laser-Induced Graphene Heater Pad for De-Icing.

The replacement of electro-thermal material in heaters with lighter and easy-to-process materials has been extensively studied. In this study, we demonstrate that laser-induced graphene (LIG) patterns could be a good candidate for the electro-thermal pad. We fabricated LIG heaters with various thermal patterns on the commercial polyimide films according to laser scanning speed using an ultraviolet pulsed laser. We adopted laser direct writing (LDW) to irradiate on the substrates with computer-aided 2D CAD circuit data under ambient conditions. Our highly conductive and flexible heater was investigated by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, X-ray diffraction, and Brunauer–Emmett–Teller. The influence of laser scanning speed was evaluated for electrical properties, thermal performance, and durability. Our LIG heater showed promising characteristics such as high porosity, light weight, and small thickness. Furthermore, they demonstrated a rapid response time, reaching equilibrium in less than 3 s, and achieved temperatures up to 190 °C using relatively low DC voltages of approximately 10 V. Our LIG heater can be utilized for human wearable thermal pads and ice protection for industrial applications.

Research on the influence of laser scanning speed on Fe-based amorphous coating organization and performance

The laser cladding method was selected to prepare Fe47Cr15Mo14Co3C15B6 amorphous coating on H13 steel surface. The structure morphology and surface properties of the cladding layer under various laser scanning speeds were compared, which were analyzed through scanning electron microscope, electron probe and X-ray diffraction to represent the micro microstructure and phase distribution of the cladding layer. The results show that, with the increase of scanning speed, there is obvious changes of the microstructure of the cladding layer. When the scanning speed was 50 mm/s, the cladding layer was made up of large amount of crystalline phase and small amount of amorphous phase. When the scanning speed was 80 mm/s, the proportion of amorphous phase in the cladding layer increased obviously, and the crystalline phase diffused in the amorphous region. When the scanning speed further increased, the amorphous phase content increased as well. In addition, with the increase of scanning speed, the hardness and corrosion resistance of the cladding layer increased greatly as well, which indicates that the amorphous phase amount has a significant influence on the properties of the cladding layer.

Ultrashort Pulse Laser Lift-Off Processing of InGaN/GaN Light-Emitting Diode Chips

Gallium nitride (GaN) film delamination is an important process during the fabrication of GaN light-emitting diodes (LEDs) and laser diodes. Here, we utilize 520 nm femtosecond laser pulses, exploiting nonlinear absorption rather than single-photon absorption such as in conventional laser lift-off (LLO) employing excimer or Q-switched laser sources. The focus of this study is to investigate the influence of laser scanning speed and integrated fluence corresponding to laser energy per area during the LLO processing of GaN LED chips and their resulting structural properties. Because both the sapphire substrate and InGaN/GaN heterostructures are fully transparent to the emission of the laser system, a key question is related to the impact of laser pulses on the quality of a thin film structure. Therefore, several characterization methods (i.e., scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and electroluminescence spectroscopy) were employed to understand the material modifications made by femtosecond LLO (fs-LLO). We demonstrated that by adjusting the laser scanning speed, smooth GaN surfaces and good crystal quality could be obtained regardless of the existing delamination of metal contact, which then slightly downgraded the LED performance. Here, the integrated fluence level was set in the range of 2.6–4.4 J/cm2 to enable the fs-LLO process. Moreover, two mitigation strategies were developed and proven to improve the optoelectrical characteristics of the lifted-off LEDs (i.e., modification of the processing step related to the metal creation and reduction of laser energy).

Experimental analysis of repairing H14 die steel surface by laser cladding

The damage of die metal parts is one of the key problems that affect its normal use. Laser cladding technology can solve this problem quickly and effectively. In this paper, the tungsten alloy powder was cladding on the metal surface by laser cladding, and the surface repair and strengthening technology were carried out. The influence of laser scanning speed on the microstructure of cladding layer metal was studied. The experimental results show that the metal parts with surface damage are repaired by laser cladding technology, and the cermet protective layer without pores and cracks is obtained. The hardness value of laser cladding layer is greatly improved than that of base material, which lays a good foundation for improving material performance.

Influence of laser scanning speed on the formation property of laser brazing diamond coating

The pre-placed BNi-2 alloy solder was utilized as braze material to fabricate brazing diamond coating on 65Mn steel substrate by using fiber laser with 5 mm × 5 mm square laser spot. The laser spot was scanned at a steady power of 1.1 kW. The effect of laser scanning speed on the formation mechanism was investigated. Different scanning speed leads to different heating conditions of solder layer, and finally leads to different melting behavior of the coating. At the small laser scanning speed (1 mm/s and 2 mm/s), the solder can be fully melted to form a small liquid ball owing to the long interaction time, and the small ball can quickly flow into the left liquid molten pool because of the high heating temperature and good fluidity. Because of its small mass, the diamond particles float on the surface of the molten pool and gather on the top of the molten pool. With the cooling and solidification of the molten pool, the diamond particles are finally fixed on the top of the coating. With the increase of laser scanning speed (3 mm/s), the solder which has not been completely melted will flip the coating toward the liquid molten ball due to the greater melting imbalance in the solder area. The initial liquid molten balls constantly gather and grow in size and finally contact with the molten pool and merge into it. However, when the scanning speed reaches 4 mm/s, the solder cannot be fully melted due to the shortening of the irradiation time of the laser spot. The graphitization degree of diamond, the exposed height of diamond and the width of coating were also studied and they are related to the previous formation process.

The influence of process parameters on corrosion behavior of Ti6Al4V alloy processed by selective laser melting

Ti6Al4V alloy exhibits good biocompatibility and has a wide range of applications in the medical fields. Additive manufacturing, especially selective laser melting (SLM), provides a new and effective way for the fabrication of Ti6Al4V alloy biological components. The corrosion resistance of SLM processed Ti6Al4V alloy needs further investigation, which is important for the application of biological components. In this study, Ti6Al4V alloy was fabricated by SLM using different process parameters. Electrochemical measurements including open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy were performed to study the influence of laser scan speed on the corrosion behavior of SLM fabricated Ti6Al4V specimens. The corrosion resistance on different planes of SLM fabricated Ti6Al4V alloy was further characterized. The electrochemical measurements indicated that the corrosion resistance was reduced as the laser scan speed increased. Microstructure analysis suggested that the inferior corrosion resistance under a high laser scan speed was related to the decreased densification behavior. Compared to the XZ-plane, the XY-plane possesses a superior corrosion resistance. The anisotropic corrosion resistance on XY- and XZ-planes of SLM fabricated Ti6Al4V alloys is attributed to the different microstructures on different planes, where more α′ martensite and less β-Ti phase were formed on the XZ-plane than on the XY-plane.

Prediction of spatiotemporal variations of deposit profiles and inter-track voids during laser directed energy deposition

The spatiotemporal variations of the molten pool and deposit profiles during laser Directed Energy Deposition (DED) largely affect the formation of printing defects and the build quality. Quantitative assessment of the dependencies of molten pool characteristics on critical process variables is helpful to reveal the evolution of the depositing tracks. To this end, a novel 3D transient phenomenological model was developed in this work to explore the evolution of the temperature and velocity fields and the molten pool dimensions for both single-track and multi-track laser DED deposits. The influences of laser scanning speed, mass feed rate, laser power, Mass per Unit Length (MUL, g/mm) and Energy per Unit Mass (EUM, J/g) intensities on the deposit characteristics were comprehensively examined. The 3D profiles of the deposited tracks were sectioned, reconstructed and visualized. The computed deposit profiles showed that the contact angles of the single-tracks increased significantly with higher MUL intensity. In contrast, the contact angle decreased with higher EUM intensity. The formation of highly convex deposits was carefully examined in particular, and a prominent bulge was found near the beginning of the deposit with local contact angle larger than 100°. The simulation results showed that convex deposit profiles obtained at high MUL intensity further caused inter-track voids during multi-track deposition.

激光扫描速度对镁合金组织演变和性能的影响

激光扫描速度对镁合金组织演变和性能的影响

Influence of Laser Scanning Speed on Phase Transformation and Superelasticity of 4D-printed Ti-Ni Shape Memory Alloys

Influence of Laser Scanning Speed on Phase Transformation and Superelasticity of 4D-printed Ti-Ni Shape Memory Alloys

Selective laser melting processing of 316L stainless steel: effect of microstructural differences along building direction on corrosion behavior

SLM-processed 316L stainless steel exhibits promoted mechanical and corrosion performances, compared with the conventionally manufactured counterparts, and has been successfully applied in many fields. The anisotropic microstructure of SLM-processed materials, caused by the layer-wise fashion of SLM processing, not only results in the anisotropy of mechanical properties but also leads to the anisotropic corrosion behavior. In this study, the influence of microstructural differences of SLM-processed 316L stainless steel along the building direction on corrosion behavior was investigated. Firstly, the influence of laser scan speed on the microstructure, hardness, and corrosion behavior of SLM-processed 316L stainless steel samples was evaluated. Then, the sample with the highest relative density and the best hardness and corrosion resistance was selected to further investigate the influence of microstructural differences along the building direction on the corrosion behavior. Results showed that the corrosion resistance improved with the increase of distance from bottom plane along the building direction. Microstructure and phase analysis revealed that the microstructural differences in crystallographic orientation and grain size along the building direction of SLM-processed 316L stainless steel led to the different corrosion behavior.

Influence of laser scanning speed on corrosion resistance and hardness properties of Fe-Mn-Si-Cr-Ni-Co alloy coating

In this study, the Fe-Mn-Si-Cr-Ni-Co alloy coatings were deposited on the polished 2Cr13 steel samples by using a laser cladding technique. The microstructure, chemical composition, hardness and corrosion resistance of laser cladding coatings were investigated, and the influence of laser scanning speed on coating’s hardness and corrosion resistance were analyzed. The research results show that laser scanning speed affects obviously the hardness and corrosion resistance of cladded coatings, when the laser scanning speed is 480 mm/min, the coating possessed the highest hardness (801 HV), the highest corrosion potential (−0.937 V) and the lowest corrosion current (1.089 × 10−5 A·cm−2).

Microstructural evolution of the amorphous layers on Mg-Zn-Ca alloy during laser remelting process

Mg-Zn-Ca bulk metallic glasses (BMGs) have been regarded as new biodegradable materials for orthopedic implants, while size constrains limit their biomedical applications. In this study, Mg-based amorphous layers with the nominal composition of Mg65Zn30Ca5 have been successfully produced using the laser remelting method. The influences of laser scanning speed on the microstructural characteristics of Mg-Zn-Ca amorphous layers during laser remelting process were investigated systematically by experiments and numerical simulations. Amorphous phase could be formed when the laser scanning speed was kept above 1000 mm/min. The remelted layer mainly consisted of a gradient structure: amorphous-crystalline composite layer, transitional layer and crystalline substrate. The increase of the laser scanning speed was benefit to improve the corrosion resistance of the remelted layer due to the formation of amorphous structure. Analysis of the temperature distributions and related thermal profiles simulated using the finite element method indicated that the crystallization could be suppressed with the increase of the laser scanning speed, which would shorten the residence time and leads to higher cooling rate in this process as well.

Finite element modelling for part distortion calculation in selective laser melting

Additive manufacturing (AM) is presently a strong candidate for automotive, medical and aerospace applications. The present work focuses on the influence of laser scanning speed on part distortion, when depositing AISI 304 stainless steel using selective laser melting (SLM). The commercial software ABAQUS was used to develop a 3D finite element model to simulate the deposition process and predict thermal gradients and part distortion. The user subroutine USDFLD was used to model powder to solid phase transformation, and the laser beam effects were modelled using the user subroutine DFLUX. In addition, heat convection within the molten pool was considered by enhancing the thermal conductivity of molten material. Also, the element birth technique was used to simulate material deposition of successive layers. The predicted results were validated by comparing them to the available literature, where a good match was found. It was concluded that higher laser scanning speeds results in lower surface temperatures and higher vertical deflections. In addition, the effect of scanning speed on temperature gradients and part distortion was found to be more evident by the deposition of subsequent layers.

Influence of Laser Scan Speed on Bronze Nickel Alloy Produced by Direct Metal Laser Sintering Technique

Influence of Laser Scan Speed on Bronze Nickel Alloy Produced by Direct Metal Laser Sintering Technique

Enhancing antireflection property of silicon through direct picosecond laser surface texturing

Crystalline silicon was laser surface textured by picosecond pulsed laser to enhance its antireflection property. The influence of laser scan speed and number of passes in fabricating the uniform surface microtexture were evaluated. Surface texture so generated was investigated and a grid of spherical domes and cavities, with nanoripples in the order of incident laser wavelength spread over it was observed. Reflectivity of bare silicon was greater than 40% and was significantly reduced well below 2% upon laser texturing, over a wavelength range of 400 to 700 nm. Antireflecting surface is an essential requirement for more efficient performance of devices for optical and photovoltaic application.

Microstructure evolution, mechanical response and underlying thermodynamic mechanism of multi-phase strengthening WC/Inconel 718 composites using selective laser melting

For further understanding the underlying relations of microstructure evolution on mechanical properties of Inconel 718 composites reinforced by WC particles using selective laser melting (SLM), the influence of laser scanning speed on microstructure growth, evolution mechanism and mechanical properties was analyzed combining with experiments and mesoscopic simulations. The obtained results apparently reveal that the Ni2W4C primary dendrites exhibit with a reduced trunk length as well as the decreasing length and spacing of dendrite arms following an increasing scanning speed according to the combining analysis of X-ray diffraction spectrum and EDS, due to the significant reduction of operating temperature and the resultantly weak atoms diffusion rate and thermodynamic driving force of dendrite growth. Meanwhile, the (Nb, M)C carbides (M representing Ni, Cr, W, Fe, Ti) generated in γ-Ni matrix are inversely refined as elevating the laser scanning speed. Both the experimental microhardness and ultimate tensile strength of SLM-processed WC/Inconel 718 composite is, therefore, evidently enhanced with a slight reduction of elongation as successively increasing the scanning speed, attributing to the combined strengthening effects of refined multi-phase of Ni2W4C primary dendrite and granular (Nb, M)C carbides. Furthermore, the underlying evolution mechanism of composite microstructure with variable processing conditions is discussed.

Influence of laser scan speed on micro-segregation in selective laser melting of an iron-carbon alloy: A multi-scale simulation study

Selective laser melting (SLM) is an additive manufacturing method complementary to traditional manufacturing technologies, and it has drawn increasing amount of attention in recent years. However, effective control of microstructure evolution in SLM is usually difficult due to the rapid heating and cooling cycles involved in the process. In this research, multiscale simulation is performed to investigate the influence of laser scan speed on micro-segregation in SLM of binary Fe-C alloy, with the consideration of realistic thermal history and powder-to-dense phase transformation. Meso-scale finite element method (FEM) is used to calculate the temperature field, and micro-scale phase field (PF) method is used to calculate the dendrite evolution and solute redistribution. Three levels of laser scan speeds, i.e., 1000, 1600, and 2400 mm/s are used to perform the simulation. The results indicate that the overall melt pool morphology and temperature distribution are significantly affected by the laser scan speed. Higher scan speed leads to significantly higher cooling rate in the interested solidification region, and therefore alters the dendrite growth velocity and tip radius. Moreover, higher laser scan speed results in lower interdendritic segregation ratio, due to ultra-fast cooling and solute trapping.

Influence of laser scanning speed on nitrided Ti6Al4V surface

ABSTRACT The influence of laser scan speed during nitriding in the range 30–150 cm min−1 on the physical properties, microstructure and corrosion behaviour of Ti6Al4V was studied. The surface energy of nitrided Ti6Al4V remained almost constant up to the scan speed of 60 cm min−1 followed by an increase in the maximum value at 80 cm min−1. A gradual drop in the microhardness of the coating from the outermost surface was noticed for specimens nitrided up to 80 cm min−1; an abrupt decrease, however, was found at a scan speed ≥100 cm min−1. The laser nitriding produced dendritic microstructure; an exponential decay in the secondary dendrite arm spacing (SDAS) with the increase in laser scan speed was revealed. The SDAS produced was smaller at the interphase and centre of the coating, compared to that at outermost surface. The passivation behaviour of Ti6Al4V at lower potentials shifted to the smaller current side after laser nitriding.

Experimental Research on Selective Laser Melting AlSi10Mg Alloys: Process, Densification and Performance

In this work, a set of experiments was designed to investigate the effect of process parameters on the relative density of the AlSi10Mg parts manufactured by SLM. The influence of laser scan speed v, laser power P and hatch space H, which were considered as the dominant parameters, on the powder melting and densification behavior was also studied experimentally. In addition, the laser energy density was introduced to evaluate the combined effect of the above dominant parameters, so as to control the SLM process integrally. As a result, a high relative density (> 97%) was obtained by SLM at an optimized laser energy density of 3.5-5.5 J/mm2. Moreover, a parameter–densification map was established to visually select the optimum process parameters for the SLM-processed AlSi10Mg parts with elevated density and required mechanical properties. The results provide an important experimental guidance for obtaining AlSi10Mg components with full density and gradient functional porosity by SLM.