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Effect of laser forming on mechanical properties of multiple-phase steels by using a thermal–microstructure–mechanical model
摘要： Based on a forming temperature-controlled mixed strain-hardening law, a temperature-controlled thermal–microstructure–mechanical model was developed to predict the deformation in ferrite–martensite dual-phase steel before and after complex laser forming. Phase transformation in dual phase steel was predicted by coupling a kinetic transformation model with the developed model during laser forming. The corresponding algorithm of the constitutive model was used in three-dimensional finite element method to simulate the material deformation and mechanical properties during the laser forming. The simulated results agree well with the experimental results. Laser forming influences the mechanical properties of the material significantly, leads to bending deformation of the scanned sample and induces a ferrite-to-martensite transformation. The influence of scanning line number on the tensile strength and bending deformation of the scanned specimen was investigated. The tensile strength and bending angle are related positively to the number of scanning lines on the sample.
关键词： Stress-strain curve,Phase transformation,Thermal–microstructure–mechanical model,Sheet metal,Laser forming
更新于2025-09-23 15:23:52
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Laser forming of nanostructures in aqueous suspensions with particular optical and photoelectrical properties
摘要： The self-organizing forming of ordered nanostructures in the aqueous suspensions with inorganic nanoparticles of nickel, copper, silica and bio-organic particles of grinded green leaves were studied by means of the irradiation with red, green and blue lasers. Various forms of self-consistent non-homogeneous distributions of the nanocomponents and the optical ?ows were found. The suspensions with high density of the nickel nanoparticles demonstrated abrupt changes of their transparency and periodicity. These abrupt changes were transformed to more slow oscillations of the particles and light distributions when the nickel particles were mixed with the nanoparticles of copper. The suspensions with the nanoparticles of copper created arc-like agglomerations explained by generation of vortexes. The vortex-like distributions were found in the suspensions with silica as well. The anisotropic agglomerations were observed during the irradiations of the suspensions with the grinded green leaves. These results are promising for the developments of new kinds of optical modulators and switchers, optical memory and green solar batteries.
关键词： laser forming,optical properties,aqueous suspensions,photoelectrical properties,nanostructures
更新于2025-09-23 15:19:57
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Investigation on the microstructure and mechanical behaviors of a laser formed Nb-Ti-Al alloy
摘要： Nb-Ti-Al alloys have attracted much attention as a potential candidate for high-temperature structural applications beyond the scope of Ni-based superalloys. Previously, Nb-Ti-Al alloys were prepared by arc-melting or hot-pressing. In this study, laser forming of the Nb-23Ti-15Al alloy is explored, and the microstructure and mechanical behaviors are systematically investigated. The results indicate that the nearly defectless Nb-Ti-Al alloy with fine dendrites could be obtained through laser forming. Three phases, β, δ and Ti(O,C), present in the alloy, and the β/δ matrix displays a columnar microstructure. Moreover, the Ti(O,C) phase, a solid-solution of TiO or TiC, appears in the alloy. Ti(O,C) is formed due to the introduction of the O and C from the elemental powder, which has a face-centered cubic (FCC) structure and a moderate lattice parameter between that of TiO and TiC. Two morphologies of Ti(O,C), large cobblestone-like particles and small dispersive particles, are observed in the alloy. Forbidden reflections of δ phase occur due to double diffraction and slight superlattice reflections of β phase arise. Furthermore, refined β/δ phases and dispersed small Ti(O,C) result in higher microhardness and fracture toughness. In brief, our results indicate that laser forming is a potential method for manufacturing Nb-Ti-Al alloys with prominent properties.
关键词： Laser forming,Double diffraction,Mechanical behavior,Ti(O,C),Nb-Ti-Al alloy,Microstructure
更新于2025-09-23 15:19:57
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Hybrid Process of Laser Heat Treatment and Forming of Thin Plate with a Small Power Semiconductor Laser
摘要： In recent years, the recycling of resources has become important because of the aggravation of global environmental concerns. In light of this, it is necessary to minimize the resource needs of current production systems. This concept is called sustainable development. When this concept is applied to machine tools, the assumption is that small parts should be processed using small machines. Additionally, the diversification of consumer needs and the ephemeralization of product life cycles are progressing in industry. As a result, the overall production system has changed from high-mix low-volume production manufacturing, to variant types in variable quantity. In this background, the cell production system is receiving attention as a production system that can achieve variant types in variable quantity. The cell production system also requires miniaturization and process consolidation of machine tools, which has given rise to the need to consolidate heat treatments, especially as part of the process consolidation of machine tools. Laser beams have proved to be effective heat sources when integrated into heat-treatment processes, such as quenching and tempering on machine tool tables. On the other hand, In the case of the thin plate, it is well known that the deformation of a plate occurs due to laser irradiation, as named a laser forming. The laser forming is also effective to generate the complex shape without a press die set. Thus, we propose that the hybrid process of laser heat treatment and forming of thin plate with a small power semiconductor laser, and demonstrate that the proposed method makes it feasible to generate the hardened sheet metal products with a compact machine tools. Moreover, considering the power consumption in laser quenching and forming process, we investigate an appropriate laser irradiation condition from a view of reducing the environmental burden.
关键词： Laser forming,Compact machine tools,Sustainable manufacturing,Laser heat treatment,Small power semiconductor laser
更新于2025-09-16 10:30:52
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Effects of Laser Beam Parameters on Bendability and Microstructure of Stainless Steel in Three-Dimensional Laser Forming
摘要： In this study, the e?ects of beam diameter and hatch spacing between the scanning paths on the bendability and microstructural behavior of an AISI 316 stainless-steel sheet in three-dimensional laser forming were investigated. The strain on the heating lines and that between the scanning tracks were numerically investigated to elucidate the e?ects of process parameters. The strain on heating lines and that between scanning tracks were numerically investigated. The increase in hatch spacing caused a larger amount of counter bending to be retained in the una?ected areas between the tracks through a process dominated by a temperature gradient mechanism (TGM), and also caused a lower deformation. The formation of small equiaxed dendrite grains instead of coarse and inhomogeneous austenite grains occurred during the process at a larger beam diameter and smaller hatch spacing, which increased the bendability of the material, owing to the decrease in anisotropy in the microstructure. Moreover, the increase in the grain size of the reheated overlap region of the deformed sample led to a higher bendability. Under these conditions, the microhardness was also increased owing to the grain boundary strengthening e?ect.
关键词： laser forming,track overlap,stainless steel,laser bending,bendability,hatch spacing
更新于2025-09-16 10:30:52
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Prediction and Optimization of Deformations in Coupling Mechanism Based Laser Forming of Sheet Metals
摘要： Fabricating three dimensional shaped surfaces from flat sheet metals by laser forming, both out-of-plane and in-plane deformations are required. This article presents the modeling of coupling mechanism activated laser forming of sheet metals based on experimental data for prediction and optimization of bending and thickening deformations. Experiments were performed based on a central composite design of experiments on coupling mechanism based laser metal forming process considering the input process parameters like laser power, scan speed and spot diameter, bending and thickening were taken as the outputs. Neural network and neuro-fuzzy system-based models were developed to carry out both forward and inverse modeling of the laser metal forming process under the coupling mechanism. Multi-objective optimization based on the non-dominated sorting genetic algorithm was used to obtain multiple optimal solutions to achieve different amounts of out-of-plane and in-plane deformations. The proposed method could guide for a suitable selection of the process parameters to produce three-dimensional shapes utilizing coupling mechanism-based laser forming using multiple laser line heating.
关键词： Coupling mechanism,Soft Computing,Laser forming,Multi-objective optimization
更新于2025-09-16 10:30:52
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Online measurement of the surface during laser forming
摘要： The laser forming process is characterized by high temperature gradients and localized deformation. The process uses a laser to introduce thermal strains. The localized deformation along with the high temperature gradients is introduced iteratively which creates a complex and dynamic forming process. To understand the dynamic behavior of the process, various models have been used. A limitation of these models is that verification is commonly based on comparison with the final shape. The present work is an attempt to measure the dynamic response during laser forming. This work will present a laser forming setup for measuring the dynamic response of a v-bend. A 2D laser range scanner was used for measuring a line perpendicular to the laser heating scan path. By scanning multiple samples and changing the relative position of the 2D laser range scanner along the laser heating scan path, a surface can be generated. Analysis of the surface shows that the plate undergoes different deformation profiles during forming—this can help in understanding the changes that incur during laser forming. A case study is performed where the experimental results are compared with a state-of-the-art numerical model with good correlation between results. This shows that the measured dynamic response can be used for improved verification of numerical models of laser forming to increase confidence in the numerical results.
关键词： Online measurements,FEM,Laser forming,AISI 304,Bending angle
更新于2025-09-16 10:30:52
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A double raster laser scanning strategy for rapid die-less bending of 3D shape
摘要： Double raster scanning approach to 3D laser forming was investigated to obtain a large deformation with one-step laser irradiation, avoiding repetitive scanning. The magnitude of the deformation during raster scanning was found to be strongly dependent on the overlapping between adjacent passes, which can be controlled by changing their spacing and the beam diameter. Therefore, 3D deformation during raster scanning has been analyzed at various overlap ratios, whose effect on the temperature and strain distribution were discussed. As the heat transfer mode significantly influences the uniformity of the bending process, the variations in bending angles with negative and positive overlapping ratios have also been investigated. The ratio of the longitudinal and lateral curvatures decreased with the increasing overlap ratio. Therefore, the effect of the lateral side is more important for specifying the final symmetry of the part, playing a critical role in bending with higher overlap ratios. In a rectangular part, deformation of the lateral side was found to be more difficult, showing strong dependence on the length of the scanning track, compared with the space of the adjacent passes. Through process characterization, the double raster scanning process has been well understood and proved to be a feasible approach to 3D laser forming of rectangular parts.
关键词： Curvature,Overlap,Laser bending,Heat transfer,Laser forming,Raster scanning
更新于2025-09-12 10:27:22
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Disk Laser Assisted Surface Heat Treatments Of AlSi10Mg Parts Produced By Selective Laser Melting (SLM)
摘要： Metal parts produced with the Selective Laser Melting (SLM) method have a great variety of uses today and because of this the requirements on the surface quality differ between applications. The surface treatments of the printed metal pieces, like other finishing phases, are often still manually worked on and thus are very time-consuming processes. This study focuses on the SLM printed AlSi10Mg aluminium specimen’s surface laser heat treatment with disk laser equipment (wavelength of 1030nm). The goal of this study was to achieve the desired effect on the aluminium’s surface quality with robotized laser heat treatment equipment. This was to show that the used finishing treatment method could be automated or robotized. The study showed that with the correct laser parameters, it is possible to generate desired effects and features on to the AlSi10Mg aluminium piece’s surface with a robotized process.
关键词： Selective Laser Melting (SLM),laser forming,AlSi10Mg,Additive Manufacturing (AM)
更新于2025-09-12 10:27:22
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Investigation of the Profile of Laser Bends with Variable Scan Distance
摘要： Laser forming is a process capable of bending sheet metal only with the laser beam and without a physical interaction with the part. The part is formed by small and local deformations by the laser beam and it is done in increments with each pass of the laser. This incremental forming makes it difficult to ensure a smooth deformation field, which can result in non-smooth components and difficulties in achieving the required tolerance of the bends. This work presents an experimental investigation of the effect of varying the scan distance, number of passes per scan line and number of scan lines on the profile of a v-bend. The v-bends were measured on both sides by a laser range scanner to determine the surface profile along the bend. To evaluate the quality of the v-bend and define the profile as discrete or continuous, the bend roundness was evaluated manually and automatically by a Least Squares Circles method and by using second order differentiation method. The effect of varying the scan distance was tested experimentally on five samples with 16 mm and five samples with 20 mm bend length. The parts were subsequently evaluated on both the inside and outside of the bend and the bend angle was measured. The results show good correlation between the manual inspection and the automatic examination. The results show that the overlapping of the laser beam paths is required to create a continuous smooth bend.
关键词： Roundness error,Laser forming,Sheet metal bending,Profile scanning
更新于2025-09-12 10:27:22