Effect Of Laser Scanning Speed Research Articles

Influence of scanning speed on titanium alloy processed with TC4+Ni60/hBN composite powder by laser metal deposition coating technology

PurposeRegarding the broadening of the titanium alloy application field, the surface treatment coating of TC4 alloy has become an essential global research topic. This study aims to illustrate the titanium-based composite coating is created by laser cladding TC4+Ni60/hBN composite powder onto the surface of the TC4 alloy.Design/methodology/approachDifferent laser scanning speeds were initially selected to prepare TC4+Ni60/hBN titanium-based composite coating on the surface of TC4 alloy using RFL-C1000 Raycus fiber laser. Second, the cladding layers with different laser scanning speeds are composed of Ti2Ni, TiN0.3, TiC, TiB, α-Ti and other phases. Finally, precision balances, friction and wear testing machines were used to analyze and test the structure, phase, hardness, wear amount and friction coefficient of the composite coating and to study the effect of laser scanning speed on the microstructure and properties of the titanium-based composite coating.FindingsIt is evident that at the low laser scanning speed, the reinforcing phase agglomeration area is distributed in the substrate as a network. Increasing the laser scanning speed can reduce the cladding layer's friction coefficient and improve the cladding layer's hardness and wear resistance. But too high a laser scanning speed will cause defects such as pores and cracks in the cladding layer and also affect the cladding layer. The bonding performance of the layer and the substrate is optimal in this research at a laser scanning speed of 10 mm/s.Originality/valueThis research has practical value in improving the quality of surface treatment coating in modern aerospace and automotive companies.

Effect of Laser Scan Speed on Defects and Texture Development of Pure Chromium Metal Fabricated via Powder Bed Fusion-Laser Beam.

Chromium (Cr) metal has garnered significant attention in alloy systems owing to its exceptional properties, such as a high melting point, low density, and superior oxidation and corrosion resistance. However, its processing capabilities are hindered by its high ductile-brittle transition temperature (DBTT). Recently, powder bed fusion-laser beam for metals (PBF-LB/M) has emerged as a promising technique, offering the fabrication of net shapes and precise control over crystallographic texture. Nevertheless, research investigating the mechanism underlying crystallographic texture development in pure Cr via PBF-LB/M still needs to be conducted. This study explored the impact of scan speed on relative density and crystallographic texture. At the optimal scan speed, an increase in grain size attributed to epitaxial growth was observed, resulting in the formation of a <100> cubic texture. Consequently, a reduction in high-angle grain boundaries (HAGB) was achieved, suppressing defects such as cracks and enhancing relative density up to 98.1%. Furthermore, with increasing densification, Vickers hardness also exhibited a corresponding increase. These findings underscore the efficacy of PBF-LB/M for processing metals with high DBTT properties.

Effect of Laser Scanning Speed and Fine Shot Peening on Pore Characteristics, Hardness, and Residual Stress of Ti-6Al-4V Fabricated by Laser Powder Bed Fusion

There is a concern regarding sub-surface pores within laser powder bed fusion of Ti-6Al-4V, which can initiate cracks and reduce mechanical properties, especially after machining for surface finishing. This study investigated the effect of laser scanning speed and fine shot peening on the pore characteristics, hardness, and residual stress of Ti-6Al-4V fabricated by laser powder bed fusion using scanning electron microscopy, X-ray micro-computed tomography, Vickers hardness, and X-ray diffraction. As the laser scanning speed increased, the number of pores and pore size increased, which reduced the hardness of Ti-6Al-4V. Most pores were less than 20 µm in size and randomly distributed. The fine shot peening generated plastic deformation and compressive residual stress on the surface, leading to higher hardness, with similar surface properties at all scanning speeds. The depth of compressive residual stress by fine shot peening varied corresponding to the scanning speeds. Increasing the scanning speed accelerated the rate of conversion between the compressive and tensile residual stresses, and decreased the depth of the maximum hardness by the fine shot peening from initial tensile residual stress within Ti-6Al-4V fabricated by laser powder bed fusion, thus reducing the enhancement achieved by the fine shot peening.

Multi-Physics Modeling of Melting-Solidification Characteristics in Laser Powder Bed Fusion Process of 316L Stainless Steel.

In the laser powder bed fusion process, the melting-solidification characteristics of 316L stainless steel have a great effect on the workpiece quality. In this paper, a multi-physics model was constructed using the finite volume method (FVM) to simulate the melting-solidification process of a 316L powder bed via laser powder bed fusion. In this physical model, the phase change process, the influence of temperature gradient on surface tension of molten pool, and the influence of recoil pressure caused by the metal vapor on molten pool surface were considered. Using this model, the effects of laser scanning speed, hatch space, and laser power on temperature distribution, keyhole depth, and workpiece quality were studied. This study can be used to guide the optimization of process parameters, which is beneficial to the improvement of workpiece quality.

Laser Polishing of Polymer Parts Produced with Material Jetting Technology: Effect of Laser Scan Speed, Overlapping and Loop Cycles

In the last year, the industrial production is characterized by the request of high level of product variety that generates a decrease of production volume changing manufacturing from mass production to mass customization. This trend let the conventional production processes, as forming, casting or moulding, expensive because of initial tools production cost that is not more amortized by the high-volume production. A solution to this scenario is to integrate Additive Manufacturing in tools production; this solution guarantees tools cost reduction also if post processes operations are needful to reduce the surface roughness produced by additive processes. Among additive processes, Material Jetting is able produce parts with guaranteed high accuracy and low average surface roughness (0.5 µm). However, these standards mainly refer to upfacing surfaces parallel to the print plate, and the roughness obtained on the other surfaces could increase up to 15 µm because of production mechanism. To improve parts roughness in this study, the laser polishing process was tested; different experimental tests were executed to investigate the effects of scan speed, overlapping and loop cycles. The results demonstrated that it is possible to improve the surface finish and reduce the roughness by 70% at the expense of dimensional accuracy.

Effect of laser scanning speed on microstructure and corrosive-wear performance of Ni-60%WC coating in Wusu mine water

PurposeThe purpose of this study is to investigate the effect of laser scanning speed (LSS) on the corrosive-tribological performance of Ni-60%WC coating in Wusu mine water, which was beneficial to improve the friction–wear performance of cylinder liner on water injection pump.Design/methodology/approachNi-60%WC coatings were fabricated on 45 steel by laser cladding, and the microstructure and tribological performance was analyzed using a super depth of field microscope and ball-on-plate friction tester, and the wear mechanism was also discussed.FindingsAt room temperature (RT, 25 ± 2 °C), the average coefficients of friction of substrate and Ni-60%WC coatings fabricated at the LSS of 6, 10, 12 and 14 mm/s are 0.48 ± 0.08, 0.23 ± 0.01, 0.21 ± 0.05, 0.22 ± 0.02 and 0.25 ± 0.04, respectively, and the corresponding wear rates are 8.755 × 104, 4.525 × 103, 1.539 × 103, 1.957 × 103 and 2.743 × 103 µm3·s–1·N–1, respectively, showing that the coating fabricated at the LSS of 10 mm/s has best friction reduction and wear resistance. The wear mechanism of Ni-60%WC coating is abrasive wear, fatigue wear and oxidative wear, which is resulted from the WC particles with the high-hardness.Originality/valueNi-60%WC coatings were first applied for cylinder liner, and the effect of laser scanning speed on its tribological performance was investigated.

Simulation and Experimental Study of Laser Processing NdFeB Microarray Structure

NdFeB materials are widely used in the manufacturing of micro-linear motor sliders due to their excellent permanent magnetic properties. However, there are many challenges in processing the slider with micro-structures on the surface, such as complicated steps and low efficiency. Laser processing is expected to solve these problems, but few studies have been reported. Therefore, simulation and experiment studies in this area are of great significance. In this study, a two-dimensional simulation model of laser-processed NdFeB material was established. Based on the overall effects of surface tension, recoil pressure, and gravity, the temperature field distribution and morphological characteristics with laser processing were analyzed. The flow evolution in the melt pool was discussed, and the mechanism of microstructure formation was revealed. In addition, the effect of laser scanning speed and average power on machining morphology was investigated. The results show that at an average power of 8 W and a scanning speed of 100 mm/s, the simulated ablation depth is 43 μm, which is consistent with the experimental results. During the machining process, the molten material accumulated on the inner wall and the outlet of the crater after sputtering and refluxing, forming a V-shaped pit. The ablation depth decreases with the increment of the scanning speed, while the depth and length of the melt pool, along with the height of the recast layer, increase with the average power.

Effects of laser scanning speed on the microstructure and mechanical properties of 2205 duplex stainless steel fabricated by selective laser melting

Specimens of duplex stainless steel (DSS) fabricated by selective laser melting (SLM) exhibit excellent strength but poor plasticity, which has limited their applications. To improve the plasticity and to achieve a strength-plasticity matching, the effect of the laser scanning speed on the density, phase, microstructure, and mechanical properties of 2205 DSS specimens fabricated via SLM is investigated. The results reveal that the molten metal is solidified according to the kinetic sequence L → δ + L → δ → δ + γ for the SLM forming process, and the sample is completely composed of the ferrite phase. The content of austenite cannot be effectively enhanced by a change in the laser scanning speed. The mechanical properties of the samples are primarily affected by the presence of pores. A scanning speed of S700 (700 mm/s) results in the formation of fewer pores, which gives rise to a high yield strength of 896.80 MPa but a poor plasticity of 15.34 %. Decreasing the scanning speed to below 700 mm/s reduces the yield strength, but it also significantly increases the elongation. The elongation of the specimens fabricated using a laser scanning speed of 500 mm/s increases to 23.09 %, and they exhibit excellent strength-plasticity matching. This increased elongation at lower scanning speeds is attributed to higher density, lower dislocation density, decreased number of grain boundaries and the higher proportion of high-angle grain boundaries (HAGBs) of the specimens. Therefore, a significant decrease in the scanning speed can improve the plasticity of the specimens fabricated by the SLM method. By changing the laser scanning speed, the density, microstructure and mechanical properties can be optimized to further improve the plasticity of the specimens.

The influence of the proportion of silica sand on cement mortar during laser irradiation

The contribution of silica sand which acts as an aggregate in concrete material on its properties has been clarified in past research. However, it is crucial to investigate the cut characteristics of cement mortar with different content of silica sand using a laser beam. In this study, cement mortars with different mixed ratios of cement and silica sand are utilized to be cut by a high-power laser beam. The influence of the silica sand content on the cut profile including melting width, kerf width, and penetration depth was clarified. Furthermore, the investigation of the glassy layer produced on the cut surface was investigated. The results show that the effect of laser scanning speed and silica sand contents on melting and kerf widths was indistinctly observed, but the difference in the penetration depth was certainly revealed. In addition, the relationship between the thickness of the glassy layer and the proportion of silica sand was established.

Effect of Laser Surface Texturing parameters on the texture formation in pure magnesium substrate

Magnesium and its alloys find a prominent application in bio-implant applications. However, their poor surface property like high corrosion rate has limited their wide usage. Various conversion and deposited coating methods are available to protect the magnesium surface from the rapid degradation. Recently, laser surface texturing (LST) has been identified as a unique surface treatment technique. In this work, LST experiments were conducted on a pure magnesium substrate with a picosecond laser system. The effect of laser scan speed and number of passes on the texture formation and surface roughness was investigated. Microstructure of the textures was investigated through scanning electron microscopy and surface roughness was investigated through White Light Interferometry (WLI). Results revealed that texture formation is accurate in lower laser scanning speed. Moreover, depth of the textures increases in lower scanning speed conditions. Surface roughness of the textures is governed by the formation of recast materials in and around the textures.

Influence of Scanning Speed on the Microstructure and Wear Resistance of Laser Alloying Coatings on Ti-6Al-4V Substrate.

Laser alloying has attracted significant attentions due to the advantages of high processing precision, good controllability and low heat effects on the substrate. However, the complexity of laser alloying requires further attentions on its processing parameters. This study aims at improving the wear resistance of the Ti-6Al-4V substrate by means of laser surface alloying with Ni-coated graphite (G@Ni). The effect of laser scanning speed is explored. The result suggests that the coating has a high surface quality and excellent metallurgical bonding with the substrate. NiTi and NiTi2 have a eutectic microstructure as well as in the TiC ceramic-reinforced phase as dendrites distribute in the γ-Ni matrix of the coatings. At higher scanning speeds, the lower energy density and shorter existence time of the molten pool refines the microstructure of the coating, improving its microhardness. At the scanning speed of 15 mm/s, the coating has the lowest wear weight loss due to its high microhardness and dense structure. This paper explores the influence of scanning speed on the microstructure and properties of the coatings, expanding the application of laser alloying on the surface modification of Ti-6Al-4V alloys.

Effect of laser scanning speed on microstructure and mechanical properties of SLM porous Ti-5Al-5V-5Mo-3Cr-1Fe alloy

In this study, porous Ti-55531(Fe) was fabricated by selective laser melting (SLM) with different laser scanning speeds. The microstructures, surface morphology, inner defects, porosity, microhardness, and compressive behaviors were studied. The variation of lattice constant and hardness were analyzed. The results show that all the specimens have a density of ∼1 g/cm3, and a Vicker’s hardness with a range of 280–320 Hv0.1. The porosity of the SLM-produced materials is greater than the designed value (77%) and increases from 77.33% to 82.33% with the increase of laser scanning speed from 500 mm/s to 1,500 mm/s. Continuous irregular columnar dendrites, a large number of gas-induced defects with small size between 20 and 60 μm and a deep molten pool form in the specimens fabricated with a laser scanning speed less than 1,000 mm/s. Some defects, elongated voids and interrupted columnar dendrites are identified in the specimens fabricated with the laser scanning speed more than 1,000 mm/s caused by the insufficient input energy. All specimens with different laser scanning speeds show the single ß phase patterns. The compressive strength of the specimens with the laser scanning speed of 500 mm/s is maintained at 32 MPa and the compressive strength decreases with the increase of laser scanning speed. The specimens with a scanning speed of 500 mm/s present the best mechanical properties and surface quality.

Microstructural evolution and corrosion properties of Fe-based amorphous coating by laser cladding on 316L stainless steel

ABSTRACT The aim of the present study was to investigate the feasibility of fabrication of a Fe53.4Cr20Mo16Cu0.6C10 amorphous and amorphous-crystalline crack-free layer with desirable corrosion resistance and hardness using the laser surface melting technique The phase analysis of clad layers has been characterised by X-ray diffraction (XRD). Also, the microstructure and phase analysis of the cross-section of clad layers has been studied by scanning electron microscopy, field emission scanning electron microscopy, and energy dispersive spectrometry. The effect of laser scanning speed on microstructure, corrosion behaviour, and hardness was investigated at 4, 6, and 8 mm s-1. The results showed that a high fraction of amorphous phase (90%) has been obtained at an 8 mm s−1 scan rate. The coating thickness is more than 150 μm, fully dense having low porosity. The corrosion resistance of Fe-based coatings was investigated by potentiodynamic polarisation and electrochemical impedance spectroscopic tests, and pitting corrosion evaluated in HCl solutions. The laser-treated material coatings had a lower current density than the substrate due to the formation of an amorphous phase, and the corrosion resistance values were 56, 162, and 141 Ω.cm2 for 4, 6, and 8 mm s−1 scanning rate samples respectively. It was found that high corrosion resistance is related to coating with a 6 m s−1 scan rate due to the mixture of galvanic effects and amorphous structure. The average measured micro-hardness of the coatings demonstrated that the sample formed from the highest scan rate possessed the highest micro-hardness, which was 824 HV.

Effect of Laser Scanning Speed on the Microstructure and Mechanical Properties of Laser-Powder-Bed-Fused K418 Nickel-Based Alloy.

Laser powder bed fusion (LPBF) is a powder-bed-based metal additive manufacturing process with multiple influencing parameters as well as multi-physics interaction. The laser scanning speed, which is one of the essential process parameters of the LPBF process, determines the microstructure and properties of the components by adjusting the instantaneous energy input of the molten pool. This work presents a comprehensive investigation of the effects of the laser scanning speed on the densification behavior, phase evolution, microstructure development, microhardness, and tensile properties of K418 alloy prepared by laser powder bed fusion. When the scanning speed is 800 mm/s, the microstructure of the material is dominated by cellular dendrite crystals, with coarse grains and some cracks in the melting tracks. When the scanning speed is increased to 1200 mm/s, a portion of the material undergoes a cellular dendrite–columnar crystal transition, the preferred orientation of the grains is primarily (001), and internal defects are significantly reduced. When the scanning speed is further increased to 1600 mm/s, columnar crystals become the main constituent grains, and the content of high-angle grain boundaries (HAGBs) within the microstructure increases, refining the grain size. However, the scanning speed is too fast, resulting in defects such as unmelted powder, and lowering the relative density. The experimental results show that by optimizing the laser scanning speed, the microhardness of the LPBF-ed K418 parts can be improved to 362.89 ± 5.01 HV, the tensile strength can be elevated to 1244.35 ± 99.12 MPa, and the elongation can be enhanced to 12.53 ± 1.79%. These findings could help determine the best scanning speed for producing K418 components with satisfactory microstructure and tensile properties via LPBF. In addition, since the LPBF process is largely not constrained and limited by the complexity of the geometric shape of the part, it is expected to manufacture sophisticated and complex structures with hollow, porous, mesh, thin-walled, special-shaped inner flow channels and other structures through the topology optimization design. However, due to the relatively narrow LPBF process window, this study will benefit from LPBF in producing a lightweight, complex, and low-cost K418 product, greatly improving its performance, and promoting the use of LPBF technology in the preparation of nickel-based superalloys.

The Effect of Wall Thickness and Scanning Speed on the Martensitic Transformation and Tensile Properties of Selective Laser Melted NiTi Thin-Wall Structures

In this study, we analyzed the coupling effect of laser scanning speed and wall thickness on the phase transformation behavior and tensile properties of selective laser melted NiTi thin-wall structures. It is demonstrated that either scanning speed or wall thickness has their respective influence rule, whereas this influence could be changed when coupling them together; that is, under different scanning speeds, the effect of wall thickness could be different. It is found that the deviation of phase transformation temperature among different wall thicknesses is ~3.7 °C at 400 mm/s, while this deviation increases to ~23.5 °C at 600 mm/s. However, the deviation of phase transformation peak width among different wall thicknesses shows little change under different scanning speeds. At low scanning speed, the samples with thicker wall thickness exhibit better tensile ductility than thinner, whereas they all show poor tensile properties and brittle behavior at high scanning speed. This uncertain influence rule is mainly due to the interaction effect between different thermal histories generated by wall thickness and scanning speed.

Effect of laser scanning speed on the microstructure, phase transformation and mechanical property of NiTi alloys fabricated by LPBF

This study investigated the effects of laser scanning speed on the microstructure, phase transformation and properties of NiTi alloys fabricated by laser powder bed fusion (LPBF). In this study, the contributions of metallurgical factors under different scanning speeds, such as Ni evaporation, Ni4Ti3 precipitation, dislocations and internal stress, to the transformation temperature and transformation latent heat were clarified through specially designed experiments. Ni evaporation is found to have the most profound effect, followed by precipitation. Increasing scanning speed is found to reduce Ni loss, thus cause less increase in the transformation temperature and transformation heat of the LPBF-NiTi alloys. Increasing scanning speed also increases the microstructure non-uniformity and thus widens the transformation temperature interval. The orientations of residual stress exhibit strong crystallographic stiffness dependence. The LPBF-NiTi alloys with different scanning speeds all exhibited high strains (>13.4%) and excellent shape memory effect. A LPBF-NiTi honeycomb structure exhibited 96% shape recovery rate after a 60% pre-compressive deformation. Besides, there is an optimum scanning speed for minimum porosity and smallest average pore size. However, the pore structure is found to have weak influence on the tensile behaviour of the LPBF-NiTi alloys, possibly due to the high defect tolerance of the martensitic transformation.

Effect of laser scanning speed of the removal quality of rust layer on carbon steel surface

Effect of laser scanning speed of the removal quality of rust layer on carbon steel surface

Effect of Laser Scan Speed on Pool Size and Densification of Selective Laser Melted CoCr Alloy Under Constant Laser Energy Density

Effect of Laser Scan Speed on Pool Size and Densification of Selective Laser Melted CoCr Alloy Under Constant Laser Energy Density

Effects of laser scanning speed and building direction on the microstructure and mechanical properties of selective laser melted Inconel 718 superalloy

This work focused on the effects of different scanning speeds and building directions on the microstructure, mechanical properties, and texture of Inconel 718 parts manufactured by selective laser melting (SLM). The microstructure evolution, including orientation texture and precipitate distribution, was studied by electron backscatter (EBSD) and scanning electron microscope (SEM), and the phase was analyzed by X-ray diffractometer (XRD). The results show that with the increase of laser scanning speed, the width-to-depth ratio of single molten pool increases, and the epitaxial growth is restricted, which leads to a decrease in the intensity of the <001> texture and a decrease in the anisotropy of mechanical properties. The grain refinement caused by the increase in scanning speed further weakens the anisotropy of mechanical properties. This work can provide potential guidance of high laser scanning speed in benefiting a more homogenous microstructure and a higher production rate for SLM manufacturing.

The Effect of Laser Scanning Speed on Microstructure and Performance of Cr3C2-NiCr Cermet Fabricated by in-situ Laser Cladding

To explore the effect of laser scanning speed on the microstructure and performance of Cr3C2-NiCr cermet layers fabricated by in-situ laser cladding, Cr3C2-NiCr cermet layers were laser cladded from Ni/Cr/Graphite (25:65:10 wt.%) elemental powder mixtures. The microstructures of the laser cladded cermet layers and the formation mechanism were investigated. In addition, the effect of laser scanning speed on the microstructure, friction and corrosion performance of the Cr3C2-NiCr cermet layers was studied. The results indicated that the in-situ laser cladded Cr3C2-NiCr cermet layers were composed of NiCr binder and Cr3C2. The laser scanning speed had a significant influence on the carbide content, composition and size. Furthermore, it affected the in-situ laser cladded cermet layer’s hardness and wear resistance. The corrosion resistance of the in-situ laser cladded cermet layer was superior to that of laser cladded nickel-based alloy and was improved with decreasing laser scanning speed.