Papers by Keyword: Laser Surface Treatment

Abstract: Laser surface texturing (LST) is an effective technique for tailoring the surface properties of Ti6Al4V alloy, widely employed in biomedical applications where surface topography plays a key role in osseointegration and functional performance. Nevertheless, the strong nonlinear relationship between laser process parameters and resulting surface roughness still limits predictive control of laser-textured surfaces. This work presents an experimental study aimed at investigating the influence of laser surface texturing parameters on the surface morphology of Ti6Al4V. Key process variables, including laser power, scanning speed, pulse frequency, pulse duration and overlap percentage are systematically varied using a fiber laser system. The textured surfaces are characterized through three-dimensional surface roughness parameters, namely Sa, Sz, Sku, Svk, and Ssk, providing a detailed quantitative description of surface topography relevant for biomedical applications. The resulting experimental dataset represents a fundamental basis for the subsequent development of artificial intelligence models, based on neural networks, for predicting surface roughness parameters as a function of laser processing conditions. The proposed approach supports data-driven optimization of laser surface texturing processes within intelligent and sustainable manufacturing frameworks.

Abstract: Laser shaping of sheet materials is a flexible process and is carried out without force contact on the material, it allows forming, among other things, brittle, elastic and difficult-to-deformed materials. It is known that the main parameters of laser shaping are the beam power, the size of the focus zone and the speed of beam movement along the surface of the workpiece, however, the range of variation of these parameters is not unlimited, but due to the characteristics of a particular equipment. Therefore, it is necessary to develop an approach to selecting processing modes that can be selected from the range available on the equipment and at the same time obtain a predictable result. There is also a need to investigate a reproducibility of laser shaping results with a lot of pass-through processing. Actually, this study is aimed at solving these issues. In particular, the article formulates a provision on complex formation parameters that allow determining interchangeable modes of laser molding processing and varying parameters in ranges available on equipment. For this, the basic processing mode was chosen, formation was carried out with a fixed number of passes, after which, using complex parameters, alternative modes were determined and formation was carried out under these conditions with the same number of passes. The article also presents the methodology and results of experimental studies of checking the interchangeability of formation modes and the repeatability of formation results during processing along parallel and multi-directional trajectories. It was experimentally found that the deviation of the strain value obtained in alternative modes, compared to the base, and did not exceed 2.46% for a three-pass cycle and 5.8% - for a nine-pass cycle. And the repeatability of the formation results during laser shaping is quite high; the discrepancy in the deformation value did not exceed 5%, and, preferably, was lower.

Abstract: The article presents the results of research on the impact of laser surface treatment on selected steel properties. The laser treatment consisted of remelting and alloying high speed steel using hard ceramic phase powders. A high-power diode laser was used in the experiment to examine the effect of parameters such as beam power and powder type on the structure and properties of the surface layer. A structural mechanism was observed consisting in obtaining, after laser processing, a super fine crystalline structure and a dendritic structure at the remelting zone. Structural changes have been found to be associated with improved properties such as hardness, microhardness and wear resistance. Steel treated with conventional heat treatment was used as a comparative material.

Abstract: Laser surface treatment is at present one of up-to-date methods for surface layer engineering, in this technique into the matrix material are introduced some amount of alloying additives. So the surface layer is obtained in form of composite material consisting of ceramic particle powders with different properties influencing the surface layer appliance possibilities. Using the technology it is possible to obtain a layer revealing a structured structure consisting of the heat affected zone (HAZ), transition zone (TZ) and remelted zone (RZ), as well as the substrate material. The laser is without cracks and defects as well as has with a slightly higher hardness value compared to the raw substrate material. The used laser power range is set in the range between 1.0 to 2.5 Kw, with the laser scan rate of the beam head in a range between 0.25-0.75 m/min, depending of the applied laser power and material used for alloying.This study was conducted to determine the effect of carbide on oxide ceramic powders addition on the microstructure and mechanical properties their changes and enhancement possibilities during a rapid solidification process of the remelted surface layer. The investigation should help to use this laser treatment technology for alloying of ceramic powder particles into the surface of light alloys, especially magnesium and aluminium. The scientific reason of this work is the usage of High Power Diode Laser (HPDL) for improvement of aluminium`s mechanical properties, especially the surface hardness and war resistance.There was found during the investigations and analysis of the results that, the obtained surface layer is without cracks and defects as well as with a relatively higher hardness compared to the raw material, after standard heat treatment. The hardness value increases according to the laser power used so that the highest power applied gives the highest hardness value in the remelted layer, similar relation can be found in the wear resistance parameters, which increases also with increasing laser power.The findings of the investigations allows to state, that the distribution of the used ceramic particles is generally satisfied, especially the carbide powder was confirmed in the alloys matrix, the particles are mainly present in the upper part of the surface layer or in the bottom zone of the remelted area. The hardness value increases in general according to the laser power used and the highest power results with the highest hardness value in the surface layer. The main aim of this work is to investigate and determine the effect of HPDL remelting and alloying on the cast Al-Si-Cu and Mg-Al-Cu cast aluminium and cast magnesium alloys micro structure for possible application in real working conditions mainly for light metal constructions as well as in many branches of the industry like automotive and rail transportation.

Abstract: Electron multipacting and electron cloud have been identified as being the major limiting factors for the beam quality or for the cryogenic system of high-intensity positive particles accelerators. Among conditioning operational techniques and other surface structuration techniques used to decrease the Secondary Electron Yield (SEY) of surfaces, laser surface treatment is a promising method to treat in situ and at atmospheric pressure copper surface of the vacuum chamber. Here, pulsed laser irradiation of copper in parallel lines pattern led to the local ablation and deposition of aggregates of copper particulates on the surface. Tests undertaken at CERN have shown that the modification of the surface morphology by creating roughness at different scales induces a decrease of the SEY by geometrical effects. Nevertheless, the mechanical strength and dust generation of the treated surface have not been addressed yet.In this work, a qualitative analysis of the multi-scale description of the surface morphology was carried out. Scanning Electron Microscopy (SEM), Focused Ion Beam (FIB), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDS) were used to investigate morphological characterization such as size and shape of the particulates, chemical composition, metallographic structures and phase transformation on the laser-processed surface.SEM and FIB examinations showed that the surface morphology depends on the local laser energy irradiating the surface and especially, relatively to the ablation threshold. TEM analysis revealed chemical composition and crystalline configuration of the treated material and helped to identify the laser modified and oxidized areas. A variety of superficial structures were observed. Potential vulnerable structures have been identified as oxidized matter redeposited on the ablated near surface. Material continuity and composition play a major role in the mechanical integrity of the generated surface morphology. The adherence of the created structures was assessed analyzing the origin of the dust extracted after mechanical stress.

Abstract: Increasingly high expectations for modern engineering, make the constantly being sought-after new processes giving traditional materials new, better features. Nowadays, next to the classic heat treatments, advanced technologies are being used increasingly, leading to much better results than ever before. The most commonly used technologies that allow for obtaining new, enhanced properties of various metal alloys in the area of surface engineering include, among others laser surface treatment. The main objective of this paper was to analyze the influence of laser surface treatment on structural change and mechanical properties improvement of Al-Mg alloy by VC alloying. The remelted layer on the aluminium alloy surface was obtained using high power fiber laser "Ytterbium Laser System YLS-4000". The surface sample was remelted using a rectangular laser beam (2 x 4mm) with a power of 3 kW (1.53e+4w/cm²). Scanning speed of the laser beam was 0.8 cm/s (0.48 m/min). The remelting area has been protected by the use of technical argon blowing. During the process, sintered particles of vanadium carbide with an average size of about 50-100 μm was introduced into the liquid metal. Ceramic powder in the remelting volume was fed with a pressure feeder (constant rate of 5 g/min). As a substrate, the ENAC AlMg3 alloy has been used. During the laser treatment, a composite layer with much better mechanical properties was obtained comparing the base material. The average hardness of the layer was about 19 HV_0.1 higher than that of the base material. Chemical analysis, carried out with the EDS (energy dispersive spectroscopy) detector and transmission microscope revealed many undissolved powder particles used in the alloying process as well as those of Al₈V₅ precipitated in the Al-Mg matrix.

Abstract: The surface of worn dies are often machined to remove the worn layer and then to re-form its shape. But, in machining operations for hardened materials, the high cutting force sometimes yields bending deflection of low stiffness tools, and results the decrease in productivity and accuracy.In this study, surface treatment by pulsed laser is applied for the high hardness materials to improve the machinability in the machining operation. Die steels are used as work material machined with ball endmills of carbide in the experiments where the cutting force and the actual depth of cut are measured to obtain the specific cutting energy and to evaluate the machinability. In endmilling operations of the nitrided die steels, the actual depth of cut is decreased by the bending deflection of endmill. However, the surface treatment with laser moderates the decreasing of the actual depth of cut. It is confirmed that the surface of workpiece pre-treated with laser has larger roughness than un-treated ones, and the specific cutting energy is decreased by laser surface pre-treatment.

Abstract: In cold extrusion of aluminum alloys adhesive wear can be prevented by an excessive lubrication of the process. While this causes additional process steps also environmental risks have to be addressed. Hence, dry metal forming, i.e. avoiding lubrication by means of coatings and topography modifications is highly desirable. In this paper first results concerning the behavior of tailored surfaces under dry metal forming conditions for pure aluminum are presented. Different surface treatments (laser polishing and Mo₂BC coating) of the tool steel AISI H11 are tested in a compression-torsion-tribometer under conditions adapted from cold extrusion. Normal stresses six times higher than the initial yield stress of the tested workpiece material pure aluminum (AA1050-O) are applied. Furthermore, a strategy for the characterization of aluminum adhesions to the tool is introduced. The influences of different topographies and the presence of a coating on the loss of material due to adhesive wear are investigated.

Abstract: Due to instrumentation and time constraints, it is infeasible to perform thorough research, especially experiments, for all the possible solutions, encompassing a full combination of materials with the expected mechanical and functional properties and the manufacturing technologies ensuring such properties. An objectivised selection of a material for research and its surface treatment technology is, therefore, essential in the planning phase of a materials science experiment. A methodology of computer-integrated prediction of development is dedicated to such task, enabling to perform an expert assessment and to present results thereof graphically using contextual matrices being a tool of a quantitative analysis that is very desirable in engineering circles. Considering the three groups of materials, i.e.: steels, casting magnesium alloys and casting aluminum alloys subjected to an expert assessment using a dendrological matrix being an inherent part of materials surface engineering development prediction methods, aluminum casting alloys has achieved the best position. It was further demonstrated that laser treatment is a technology of the highest potential and attractiveness in the context of applying aluminum casting alloys for surface treatment.

Abstract: The purpose of this paper was the investigation of laser treatment influence on the microstructure and properties of the surface layer of heat treated Al-Si-Cu cast aluminium alloys, using the high power diode laser (HPDL). The performed laser treatment involves remelting and feeding of ZrO₂ ceramic powder into the aluminium surface. Based on the performed investigations it was possible to obtain the layer consisting of the heat affected zone, transition zone and remelted zone, without cracks and defects as well as has with a slightly higher hardness value compared to the non remelted material. The laser power range was chose as 1.5 to 2.0 kW and implicated by one process speed rate of 0.25 m/min. Also a powder size was used for alloying with the particle size of ca. 100 μm. The hardness value increases according to the laser power used so that the highest power applied gives to highest hardness value in the remelted layer [1-8]. The carried out investigations allow to conclude, that as a result of alloying of the heat-treated cast aluminium alloys with oxide ceramic powder the surface layer can be enriched with the powder particle and in some cases a high-quality top layer is possible to obtain. Very often to determine conditions of laser treatment are being used the numerical methods that would significantly shorten the time to find the most optimal parameters. [8]. Concerning original practical implications of this work there was important to investigate the appliance possibility of High Power Diode Laser (HPDL) for enhancement of the aluminium surface properties, especially the wear resistance and hardness. the scientific reason was also to describe structure changes and processes occurred in the laser remelted surface aluminium layer after ZrO₂ feeding using HPDL laser [10-1. .