Papers by Keyword: Laser Treatment

Abstract: This article is devoted to establishing the relationship between the state of the material, phase transformations, and the formation of the microstructure of structural steels widely used in mechanical engineering, as well as for the manufacture of welded sealed bulk structures including capsules for hot isostatic pressing.

Abstract: A number of parts of roller-screw mechanisms (RSM), which work in aggressive environments, are made of corrosion-resistant stainless steel 40Cr13 (AISI420 analogue). These elements include a screw and rollers. For these parts, it is necessary to have hard surface layers and a soft core. A promising method for obtaining the necessary requirements is surface laser modification. The article investigated the effect of laser surface treatment on the value of the coefficient of elasticity, hardness, coefficient of friction and the amount of wear of products made of stainless alloy steel 40Cr13. For laser processing, the SVAROG-1-5DR laser complex (Russia) was used. Various modes of surface laser modification were set. For this purpose, the power of the laser power, the speed of movement of the laser beam relative to the treated surface, and the focal length were varied. The Vickers hardness and tribological characteristics were measured using a microcombitester and tribometer manufactured by SSM Instruments SA (Switzerland). The Rockwell hardness was measured using a TN 301 hardness tester manufactured by Time Group (China). The structure of the alloy was studied by metallography and X-ray diffractometry. It was found that the indicators of hardness and wear resistance of the surface layers of sctructural 40Cr13 steel strongly depend on the laser treatment modes. These dependencies are extreme, with highs and lows. The paper presents the quantitative values of the hardness and wear resistance indicators before and after laser treatment of the surface of this steel in various modes. The reasons for the change in the hardness and wear of the surface layers of 40Cr13 steel after laser treatment under different modes are established. The results of the work were used to optimize the modes of laser treatment of the surface of 40Cr13 steel in order to obtain the maximum values of hardness and wear resistance.

Abstract: The article contains the results of experiments carried out on laser irradiation of steels in a constant magnetic field. The experiment shows it possible to increase the cooling speed while heat transfer decreases from the surface into lower metal layers, which slightly reduces laser-hardened layer depth, increases convective mixing of the fusion area, which have a positive impact on the surface layers quality of steel and alloys. This has a positive effect on strength product properties. Magnetic field processing of metal reduces the degree of local plastic deformation of irradiated layer due to magnetostriction phenomenon. Magnetic field superimposition contributes to two-phase decay of the martensite, and reduces residual stresses and crack risk.

Abstract: The ability to control the mechanical properties of metal alloys is an urgent task in materials science. For formation of certain operational properties, in most cases, it is enough to treat the working surface of the product by laser radiation. Classical processing methods are ineffective in relation to multicomponent amorphous-nanocrystalline metallic alloys. This is due to their limited use. Usually, this treatment leads to the loss of unique properties the amorphous-nanocrystalline material. Increasing crack resistance and microhardness is not an easy problem. The structure of an amorphous nanocrystalline material can be destroyed under the action of laser processing. Laser nanosecond treatment, as result of a complex effect on the surface, slightly affects the structure of material. The treated material is characterized by increased microhardness and crack resistance, while at the same time such changes may be controlled.

Abstract: This article deals with laser treatment of plasma spraying of PG-CP4 powder on steel 40H13. A multi-factor model is obtained that relates the friction coefficient of the coating to the radiation power W, the longitudinal feed of the laser beam Spr, and the distance L from the protective glass of the laser head to the sample’s surface. The model allows you to control the modes of laser processing, in order to reduce the friction coefficient of the coating. The greatest influence on the friction coefficient is exerted by the longitudinal feed Spr of the laser beam, followed by the radiation power W and the distance L. A multi-factor model of the friction coefficient of uncoated 40H13 steel treated under the same conditions as coated 40H13 steel is also established. Comparison of the two variants showed that of all the samples providing reliable adhesion of the coating to the substrate, the greatest reduction in the friction coefficient (by 30.2 %) was achieved at W = 5 kW, Spr = 25 mm/s and L = 85 mm. The results of the research are recommended for use in enterprises that implement the processes of plasma and laser processing of materials, as well as in design organizations that develop modern laser systems.

Abstract: This work represents the characterization of materials surface before and after laser processing with macrophotography, optical metallography, and scanning electron microscopy before and after thermal exposure. The factors influencing the reliability of the laser-induced code readability have been determined as color and contrast. The range of stability of the code readability under thermal influence on the structural materials under study was determined, which allows improving the reliability of the laser-induced marking codes readability. The research objects in this paper were samples of the following materials: alloys based on copper, aluminum, and iron with laser-induced codes of various types applied on the surface. This work aimed to research the stability of laser-induced codes readability after thermal exposure using macrophotography, optical metallography and scanning electron microscopy on structural materials of various purposes before and after laser processing (when forming a binary matrix code). The research results obtained and presented in this article on the stability of laser-induced codes reading under thermal action on structural materials can be used in different fields of industry, when marking products of heavy, general, medium, and precision engineering, as well as for marking metal products and blank parts. The results of this research are also planned to be used for further analysis of the occurring damage, leading to reading errors due to mechanical and chemical influences. It is planned to evaluate the limit values of the parameters that determine the degree of degradation at which the encoding will be considered to have lost the recognizing ability. Requirements for the quality and permissible code damage will also be developed to ensure their reliable identification.

Abstract: The article considers the effect of laser treatment of bearing steel on the change in the elasticity modulus and hardness of the steel SHH15SG. Multi-factor models were obtained that relate the output parameters to the power W of laser radiation, the longitudinal feed Spr of the laser beam and the distance L from the protective glass of the focusing head to the workpiece surface. According to the degree of reduction of the influence on the elastic modulus of steel SHH15SG subjected to laser treatment, these factors are arranged in a sequence: W, Spr, and L. With increasing W and L the modulus of elasticity and hardness of the treated surface layer increase. 3M-XYZ surface-graphs, 3M-XYZ contour-graphs of interactive influence of independent factors on the elastic modulus and hardness of the surface layer are constructed, which simplifies the procedure for assigning the processing mode. The research results are useful for manufacturing and design companies that implement laser technologies and create laser equipment.

Abstract: Joining carbon fibre reinforced composites with adhesive are widely used in various applications including aircraft structures and commercialized leisure products. However, surface contaminations hinder the adhesion of the bonding. Laser based surface treatment on bonding surface is suggested to improve the adhesion on the surfaces for secondary bonding. In this paper, single lap shear tests of the samples show that the laser pre-treated samples lead to the higher joint strength then acetone cleaned reference samples and surface sanded samples. The failure mode changed from adhesion failure in the reference sample to cohesion mode in the laser treated samples. The structure, topography and morphology of the composite surfaces which were pre-treated with laser radiation were observed. A correlation between surface properties and adhesive bonding strength was investigated. It should be noted that the variation of the pulse frequency level of the laser treatment contributed to the fibre breakage and the epoxy removal level of the sample surfaces.

Abstract: This research aimed to prepare (Fe-Ni) alloy by powder technology method for its technological and commercial importance. Iron and Nickel powders were tacking then their powders mixed and blended together with percent (63% Fe-37% Ni), then the powders compacted isostatic cold pressure at (6 ton). Laser surface treatment was done for the samples with different energies (0, 200, 260, 300) mJ and pulse time (10 sec) At a distance (100 cm). The X-ray diffractions test indicated that all samples have Face Center Cubic (F.C.C), and the samples at 300 mJ has best properties which include increase of phases intensity and decrease of grain size according to Debye-Scherrer equation. The Atomic Force Microscope (AFM) also shows better properties with increase laser energy. Where increased soft-ness of surface, homogeneity surface and decrease in grain size with increase laser energy. The laser analysis resulted that melting all surface molecules which led to improvement in the structural properties.

Abstract: The processes of structure formation in the bimetal М1 + VТ1-0 after laser treatment from the side of copper are studied. The structure, phase and chemical composition of the interaction zone was investigated, the factors influencing the change in its hardness were determined.