Effects Of Laser Processing Parameters Research Articles

Analysis of synergistic friction reduction effect on micro-textured cemented carbide surface by laser processing

The tribological properties of circular pit, square pit, ring groove micro-textured surface and smooth cemented carbide surface were analyzed by finite element simulation method. Through theoretical analysis and friction and wear test, the tribological properties of circular pits micro-textured (CPMT) cemented carbide surface under the synergistic effect of laser processing parameters and texture arrangement parameters were deeply studied, and the interaction relationship between various influencing factors was developed. Finally, the wear morphology and element distribution of the smooth surface and the CPMT cemented carbide surface were analyzed by SEM. The results show the CPMT surface has better friction performance by comparing with other types of surface micro-textures and smooth surfaces. The laser processing parameters and arrangement parameters of the CPMT are obtained by response surface optimization: laser energy with 1103.494 J/mm2, scanning speed with 991.2 mm/s, scanning times with 3, and the radial and circumferential distance of the micro-texture with 120 μm and 182 μm, respectively. This paper establishes a systematic preparation process and design theory of surface micro-texture, which provides an important theoretical basis for the further optimization research in the field of micro-textured tools.

이종 폴리머 소재의 레이저 투과 용접 시 용접부의 전단 특성 연구

In this study, laser transmission welding of two heterogeneous polymeric materials was performed and the effect of laser process parameters on the weld joint strength was investigated by shear test corresponding to ASTM standard D3163-01. Specifically, laser transmission welding of 2 ㎜ thick PMMA and PC/ABS was performed using a thulium laser with wavelength and focusing diameter of 2 ㎛ and 1 ㎜, respectively. The experimental results showed that the bonding strength increases as the laser energy transmitted to the welding zone increases, but too strong energy causes a decrease in the mechanical properties of the heat-affected zone. Thus, it is necessary to find the laser process parameters (Maximum Laser Power and Laser Scan Speed) that can secure sufficient bonding strength within the allowable range where surface defects do not occur in the actual process.

Surface laser processing of maraging steel parts manufactured by selective laser melting: effect on pass geometry and hardness

Due to the possibility to produce the parts with complex internal and external geometries, selective laser melting (SLM) process attracts growing interest in various fields of engineering segments such as aircraft, aerospace, biomedical, automotive, marine industries and tooling. Maraging steels, having excellent weldability and high resistance to thermal fatigue due to the lack of carbon, has showed good suitability for SLM [1]. However, owing to the limited hardness and wear resistance, maraging steels has limited application at the harsh wear conditions [4]. In this study, the possibility to improve the surface characteristics of DIN 1.2709 steel SLM parts by application of laser alloying technology is evaluated. The surface of SLM part was laser processed at various laser spot diameters and varying laser scanning speeds from 500 to 1500 mm⋅min-1, with and without preposition of alloying element. The power density was provided in the range from ~0.8⋅103 W⋅cm-2 to ~51⋅103 W⋅cm-2 and heat input – from 4 to 12 J⋅mm-1. The effect of laser processing parameters and presence of alloying element on the geometry of obtained processed passes and hardness of surface was evaluated. It was determined, that the application of CO2 continuous laser at the parameters of 1 kW laser power, 0.5 mm laser beam spot diameter and laser scanning speed in the range between 500 mm⋅min-1 and 1250 mm⋅min-1 allows obtaining laser pool of acceptable geometry and sizes directly on as-manufactured SLM part surface without any pre-processing. The increasing scanning speed to 1500 mm⋅min-1 or spot size to 2.0 and 3.0 mm results in too small pool depth and unstable pool geometry. The laser processing with preposition of alloying element layer provided surface alloying effect of the maraging steel SLM part. The hardness of processed surface areas ranged between ~600 HV0.2 at the lowest scanning speed and ~1770 HV0.2 at the highest speed, what is from 18% to ~3.5 times higher, as compared with maximum hardness of 1.2709 maraging steel after aging (~58 HRC or ~510 HV).

Effect of laser processing parameters and carbon black on morphological and mechanical properties of welded polypropylene

In the present work, laser process window and welding suitability of the neat isotactic polypropylene (iPP) and its carbon black (CB: 0–3 wt.%) composites was defined for laser transmission welding (LTW) with the help of thermal characterisation and thermal simulation. This novel approach of welding feasibility moves from trial and error to robust analytical methods. The non-contact spacer method is also a novel feature of this study, followed by X-ray diffraction of the laser-treated iPP composites. This study emphasises the importance of crystallinity in defining weld integrity and quality. The welding experiments were conducted with line energies of 0.06–0.12 J/mm using the Response Surface Methodology approach by varying laser power and welding speed. The composites with 0.5 wt.% and 1.0 wt.% of CB were welded successfully with neat iPP, but composites with CB (>1 wt.%) were difficult to weld due to degradation. Weld lap shear strength and apparent weld width measured during mechanical testing showed better weld quality for 1 wt.%CB welded at line energy 0.12 J/m. Mathematical models have been developed based on the experimental results of central composite design after backward elimination. The present study demonstrates that an increase in CB to an optimised value fulfils the requirements of high welding speed with improved crystallinity and weld strength. This study is of keen interest to industrialists and researchers.

AN EXPERIMENTAL INVESTIGATION OF LASER TRANSFORMATION HARDENING OF UNALLOYED TITANIUM USING ND:YAG LASER

This research paper presents the investigation on laser transformation hardening (LTH) of unalloyed titanium of 1.6mm thickness sheet, nearer to ASTM Grade 3 of chemical composition was investigated using 2KW CW Nd: YAG Laser. The effects of laser process parameters: laser power750-1250W), scanning speed (1000-3000 mm/min) and focal point position (-10mm to -30mm) on the hardened bead profile parameters such as hardened bead width (HBW) and hardened depth (HD) was investigated using Response Surface Methodology (RSM). The experimental design is based on an independent quadratic Box-Behnken Design (BBD) matrix. The reduced linear and quadratic polynomial equations for predicting hardened bead width and hardened depth of bead profile were developed. Adequacies of models were examined by Analysis of Variance (ANOVA) technique. The results designate that the mathematical models developed predict the responses adequately adequate within the limits of hardening parameters being employed. It is recommended that the regression equations can be used to find optimum laser hardening conditions for desired criterion.

Fabrication and properties of micro-additive manufactured Ni-based composite coatings by short-pulsed laser

Laser micro-additive technology exhibits excellent promising applications in processing microelectronic components, fabricating medical implants and improving local properties of micro-devices. In this paper, laser micro-additive technology is utilized to fabricate Ni-based micro-cladding coatings by a short-pulsed laser with the pulse width of 10 ns and maximum power of 20 W, and the effect of laser process parameters on micro-cladding coatings is investigated. Results exhibit that the surface quality of micro-cladding coatings is seriously influenced by the process parameters, and the optimal laser process parameters: power of 16 W, scanning speed of 20 mm/s, transverse overlap ratio of 0.8 and frequency of 20 kHz (laser energy density of 160 J/mm3) are obtained. Subsequently, the immersion tests are carried out for evaluating the oxidation and corrosion properties of Ni-based coatings, and the coatings with the thickness of 10–15 μm exhibit excellent anti-oxidation and anti-corrosion properties compared to substrate due to the shielding effect of micro-cladding coatings. In oxidation region, Fe3O4 and Fe2O3 oxidation layers are formed on substrate accompanied by large amounts of β-FeOOH, γ-FeOOH and α-FeOOH; however, less oxidation reaction occurs on coating surface. In corrosion region, the substrate is covered by granular structures with more β-FeOOH, γ-FeOOH and a few α-FeOOH, and the coating surface is quite smooth with few defects of exfoliation.

Fabrication of superhydrophilic surfaces for long time preservation on 316 l stainless steel by ultraviolet laser etching

Due to the good biocompatibility, 316 l stainless steel is widely used in the manufacture of medical instruments and human implants. The super hydrophilic 316 l steel surface is used for reducing friction and adhesion. By choosing appropriate laser process parameters 316 l steel surfaces with super-hydrophilic were obtained. The effects of laser process parameters including repeat frequency, pulse width, scanning speed, and the number of scanning were investigated to find the relationship between surface microstructure and wetting ability. To investigate the super-hydrophilic maintenance time on the textured surface, the textured surfaces were preserved in ambident air, distilled water, and absolute ethanol. The results showed that by choosing appropriate laser process parameters surface with super-hydrophilicity can be maintained for 30 d.

Microstructural and mechanical characterization of parallel layered WC- NiCr weld overlay on 080 M40 steel substrate prepared using additive manufacturing

080 M40 Medium carbon steel has potential applications in axles, shafts, bolts, studs, spindles, automotive components and many more. In high friction applications these steels possess better wear resistance, and after weld overlay, they can exhibit superior properties. Additive manufacturing (AM) is an advanced method in which material in the form of powder or wire is used to form a desired shape. Laser Metal Deposition (LMD) is an AM method which is used in industrial application to recreate, repair and produce corrosion resistance weld overlay on a part. In comparison with conventional overlay techniques such as Plasma Transfer Arc (PTA), Metal Inert Gas (MIG) & Tungsten Inert Gas (TIG); Laser weld overlays are faster techniques which can make thin sections with good metallurgical bond and with high productivity and flexibility. Apart from that it has also advantage of low heat affected zone, minimum metal dilution, and can produce thin layers with good aesthetics. In this paper, 080 M40 steel samples were used as substrate and WC- NiCr powder was weld overlayed using LMD method. Such kind of weld overlays will be had potential application in the field of mining. The weld overlay was deposited in parallel layered fashion and effect of set of parameters like feed rate, dilution, size of the bead and processing speed were used to produce weld overlays of 1 mm thickness. metallurgical, micro structural and mechanical properties of these weld overlay materials have been investigated. These properties are very important in the processing of mining tools as well as other parts produced using the LMD process and also for other future applications. Further effect of laser processing parameters on the resulting properties of these steels weld overlays are discussed.

Fabrication of hierarchical structures on titanium alloy surfaces by nanosecond laser for wettability modification

Titanium alloy is widely used in aerospace industry due to its low density, high specific strength and high-temperature resistance. To broaden its application scope, superhydrophobicity of titanium alloy is required in certain situations, such as self-cleaning and anti-icing. In this study, direct nanosecond laser ablation was applied to fabricate distinct pits with hierarchical structures on titanium alloy substrates, followed with chemical treatment to modify the wettability of the surfaces. The effects of laser processing parameters on surface morphology and surface wettability were explored systematically. Results show that, increasing the number of scans improves the depth of the pits and the accumulation of the micro-nano structures around the craters. The scanning space mainly affects the overlap of the heat affected zones, and hence the distribution of the laser-induced hierarchical structures. The wettability of a laser processed surface is determined by both surface roughness and surface chemistry, and the solid fraction of the rough surface is regulated by the number of scans as well as the scanning space. Moreover, superhydrophobic surfaces are obtained on the laser processed titanium alloy after chemical treatment, which has great potential for the as-mentioned applications.

Effects of laser processing parameters on properties of laser-induced graphene by irradiating CO2 laser on polyimide

Effects of laser processing parameters on properties of laser-induced graphene by irradiating CO2 laser on polyimide

A review on coating with high entropy alloy developed by laser energy based surfacing process

This review paper discusses about the deposition of coating with high entropy alloy on metallic materials by laser energy based surfacing process. The purpose of coating is to deposit a hard and wear resistant layer of expansive material on the surface of workpiece material without altering the bulk properties of the workpiece to increase its surface properties. The coating with high entropy alloy shows excellent surface characteristics like corrosion resistance, wear resistance and oxidation resistance at high temperature. Due to high power density and fast cooling rate, laser cladding is most suitable technique for synthesis of coating with high entropy alloy. Coating with high entropy alloy is generally developed on titanium alloy, magnesium alloy, aluminium alloy, copper alloy and ferrous alloy by laser based cladding process. In this paper effects of laser process parameters on high entropy alloy coating developed on various industrial materials has been discussed. The various laser parameters which affect the properties of coating with high entropy alloy are laser power density, laser scanning speed, feed rate of powder, argon flow rate, and frequency. The high entropy alloy exhibits effect due to high entropy, effect due to slow diffusion, cocktail effect and effect due to severe lattice distortion, which leads to tailoring of microstructure and exhibits to excellent surface hardness, corrosion resistance and wear resistance. This paper describes about the brief review on benefits of high entropy alloy coating, challenges arises, suggested remedies for future research work and its applications in aerospace, automobile, marine and chemical industries.

Prediction of solidification microstructure of titanium aluminum intermetallic alloy by laser surface remelting

By controlling the processing parameters in the laser additive manufacturing (LAM) process, the mechanical properties of titanium aluminum alloy could be modified. However, the difficulty of optimizing the solidification microstructure is to build the relationship between the microstructure and processing parameters. To solve this problem, a numerical model of combined processing parameters with dendrite arm spacing was developed in this paper to predict the solidification microstructure and reveal the effects of laser processing parameters on dendrite arm spacing. A geometry factor (α) was first introduced in the prediction model to correct the simulated molten pool shape to improve prediction accuracy. Moreover, the nonequilibrium solidification of LAM due to fast cooling was taken into consideration in this study. Based on the model, primary dendrite arm spacing (PDAS) and secondary dendrite arm spacing (SDAS) in laser surface remelting of Ti-47Al-2Cr-2V alloy were investigated in combination with simulations and experimental observations. The experimental results indicate that the model calculated using average solidification conditions applies well in predicting the solidification microstructure of titanium aluminum alloy. The dendrite arm spacing slightly decreases at low scanning velocity but increases at high scanning velocity as the laser power increases. In addition, the scanning velocity plays a dominant role in the change in dendrite arm spacing when the scanning velocity is lower than 600 mm/min, and the impact of laser power on dendrite arm spacing gradually increases as the scanning velocity increases.

Optimization of Laser Parameters and Dimple Geometry Using PCA-Coupled GRG

Stainless steel (SS316L) is applied in numerous fields due to its intrinsic properties. In this study, micro-dimples were fabricated on SS316L. The effects of laser process parameters, such as frequency, average power, and pulse duration, on the average dimple diameter, dimple distance, and dimple depth were studied using an L9 orthogonal array. The analysis of variance (ANOVA) and multi-objective optimization technique, principal-component-analysis-coupled grey relational grade (GRG), was used to optimize laser process parameters on output responses. The optimal machining parameter settings obtained for the highest GRG peak value of 0.2642 are 15 kHz (frequency), 12 W (average power), and 1500 ns (pulse duration). The ANOVA results showed that average power is the most influential factor, contributing 86.40 % to performance measures (average dimple diameter (φ), dimple distance (d), and depth (l). Moreover, the effect of process parameters was studied using mean effect plots, and the micro-dimple quality was analysed using SEM micrographs.

Effect of Laser Processing Parameters on Microstructure, Hardness and Tribology of NiCrCoFeCBSi/WC Coatings.

In the present study, pulsed laser post-processing was applied to improve the properties of the thermally sprayed NiCrCoFeCBSi/40 wt.% WC coatings. The powder mix was deposited onto a mild steel substrate by flame spray method and then the as-sprayed coatings were processed by Nd:YAG laser. The peak power density applied was between 4.00 × 106 and 5.71 × 106 W/cm2, and the laser operating speed ranged between 100 and 400 mm/min, providing processing in a melting mode. Scanning electron microscopy, energy dispersive spectroscopy, Knop hardness measurements, and “ball-on-disc” dry friction tests were applied to study the effect of the processing parameters on the geometry of laser pass and microstructure, hardness, and tribology of the processed layers. The results obtained revealed that pulsed laser processing provides a monolithic remelted coating layer with the microstructure of ultrafine, W-rich dendrites in Ni-based matrix, where size and distribution of W-rich dendrites periodically vary across remelted layer depth. The composition of W-rich dendrites can be attributed to a carbide of type (W, Cr, Ni, Fe)C. The cracks sensitivity of coatings was visibly reduced with the reduction of power density applied. The hardness of coatings was between ~1070 and ~1140 HK0.2 and correlated with microstructure size, being dependent on the processing parameters. The friction coefficient and wear rate of coatings during dry sliding were reduced by up to ~30% and up to ~2.4 times, respectively, after laser processing.

Numerical and experimental study on laser soldering process of SnAgCu lead-free solder

Laser soldering has been widely used in the connection of the electronic components and printed circuit boards. Normally, the temperature and thermal stress of solder joints significantly influence the soldering performance and the reliability of solder joints. However, it is difficult to be accurately measured by the experiment during laser soldering process. In order to reveal the effect of laser process parameters on the temperature and thermal stress of SnAgCu solder joints, a novel 3D transient thermo-mechanical coupling numerical model is proposed using finite element method. The numerical simulation results reveal that the temperature and the thermal stress as well as the deformation of the as-soldered samples are proportional to laser output power and output time. These results demonstrate that the fine and uniform microstructure is obtained for SnAgCu solder and the micro Vickers hardness reaches to the maximum value of 38.3 N at the condition of laser output power of 16 W and laser output time of 0.8 s. The good consistency between the experimental and simulation results proves that the finite element model may effectively predict the temperature distribution and stress distribution, which provides a new pathway for the optimization of the laser soldering parameters in the application of electronic components and PCB.

Microstructure and Corrosion Behavior of Ti-Nb Coatings on NiTi Substrate Fabricated by Laser Cladding

Ti-23Nb (at.%) coatings on an NiTi alloy with metallurgical bonding were prepared by laser cladding (LC) technology using Ti-Nb mixture powders. The effects of laser processing parameters on the microstructure and mechanical properties of the coatings were systematically investigated and the corrosion resistance of the coatings was assessed. The coatings were composed of TiNb, (Ti, Nb)2Ni, and β-Nb phases. The coatings increased the hardness of the NiTi alloy by a combined strengthening effect of the eutectics and fine microstructure. The corrosion resistance of the coated part was improved. The coatings with great corrosion resistance could keep the coated parts inert in an aggressive environment, and effectively restrain the release of toxic Ni ions, which means that the Ti-Nb alloy coatings are likely to be used as a biomaterial for medical applications.

A new sealing technology for ultra-thin glass to aluminum alloy by laser transmission welding method

An experimental study on laser transmission welding of transparent glass and aluminum alloy by a millisecond pulsed laser is reported for the purpose of hermetically sealing glass to metal. Prior to the laser sealing process, an oxide coating is prepared on the aluminum alloy surfaces using the micro-arc-oxidation process. The effect of laser processing parameters on the shear force, weld seam morphology, and weld joint interface is investigated, and the formation mechanism of the weld seam is analyzed. The results show that the micro-arc-oxidation coating can effectively act as a laser energy absorbing layer and buffer layer of weldments. In addition, the main reason for realizing the connection between these two materials lies in the mixed mosaic structure formed within welds. When the laser power is 100 W, laser pulse width 2.5 ms, welding speed 3 mm/s, and laser frequency 10 Hz, the weldments can obtain good sealing.

Effect of Laser Treatment on the Surface Roughness of Multilayer Plasma Sprayed Thermal Barrier Coating System

Thermal barrier coatings (TBCs) are used in advanced engines working at higher temperatures. Higher efficiency and performance of gas turbine engines will require careful selection of TBCs. In this study, Ni22Cr10Al1.0Y (Amdry 9625) bond coat and two types of top coat including ceria stabilized zirconia (CSZ) ZrO2-24CeO2-2.5Y2O3) and yttria stabilized zirconia (YSZ) ZrO2-8Y2O3 were deposited on IN 625 by air plasma spraying (APS). The thickness of the duplex ceramic coat based on zirconia was in the range between 350 to 400 µm. The effect of high power Yb:YAG solid state laser at different laser parameters on feature, microstructure and roughness of plasma sprayed and laser sealed coating of multilayer ceria stabilized zirconia/ yttria stabilized zirconia was investigated. Surface roughness has been reduced significantly after laser sealing. The effect of laser process parameters carried out using Taguchi’s L16 orthogonal array design. Minimum roughness can be obtained at moderate power density and longer interaction time with sufficient specific energy to produce complete melting of coating. Characterization and analysis of results was achieved by employing scanning electron microscopy (SEM) , (EDS) and image J analysis. It was found from the results, there were significant improvements in the performance of plasma sprayed coatings after laser sealing due to the reduction of surface coating defects.

Formation of bionic surface textures composed by micro-channels using nanosecond laser on Si3N4-based ceramics

Bionic surface textures exhibit excellent properties in improving the friction and wear resistance. To obtain the micro-channel bionic textures with high-quality on Si3N4/TiC ceramic surface, the effect of laser process parameters by using a nanosecond laser with 1064 nm wavelength on micro-channel surface quality and geometry is studied. The surface morphology, depth and width of the micro-channels are examined by scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM). The surface compositions of heat-affected are detected by energy dispersive spectrometer (EDS). Results show that the surface morphology and geometry of the micro-channels are seriously influenced by the laser process parameters. Higher laser power, lower scanning speed, higher frequency and overscan are prone to produce larger channel depth and width due to more accumulated energies. The optimal laser process parameters of the micro-channels are obtained, correspondingly the micro-channel depth and width are about 40–45 μm and 55–60 μm, respectively; meanwhile, it is found that the oxidation occurs in the heat-affected zone. Finally, five kinds of bionic surface textures orderly composed by micro-channels (square, circle, diamond, hexagon and sector) are fabricated on Si3N4/TiC ceramic surface based on the optimal laser process parameters.

Removal mechanism of 2.5-dimensional carbon fiber reinforced ceramic matrix composites processed by nanosecond laser

C/SiC composite material is widely used in aerospace fields because of its excellent properties; however, it is difficult to be removed and processed. In this paper, the 2.5-dimensional C/SiC composite material was ablated by nanosecond laser to explore the laser removal mechanism. Firstly, the laser ablation experiment was carried out to investigate the gradual process of ablation morphology with the increasing laser power density. Secondly, the characteristics of ablation holes were analyzed, and the effects of laser processing parameters and fiber orientation on the ablation morphology and size were studied. In addition, the ablation morphology of needle-punched fiber area was analyzed to expound the unique ablation removal characteristics of 2.5-dimensional C/SiC composites. At last, ablation removal mechanism of 2.5-dimensional C/SiC composites was summarized, and the model of ablation removal process was established. The results indicated that ablation morphology was evolved from nothing to ablation mark, to fiber expansion, to fiber shrinkage and tension, to resolidification, to removal holes, and to increasing holes with laser power density. Besides, the ablation morphology in needle-punched fiber area was different from elliptic ablation morphology in the 0° or 90° fiber area, the ablation holes in the needle-punched fiber area were smaller and deeper, and the ablation holes were approximately circular. The results would provide theoretical basis and technical support for processing functionalized structure of 2.5-dimensional C/SiC composites by nanosecond laser, such as blind holes, grooves, and square holes.