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Improvement of classification accuracy of stainless steel alloys by laser-induced breakdown spectroscopy based on elemental intensity ratio analysis
摘要： Laser-induced breakdown spectroscopy (LIBS) is a useful technique for accurate sorting of metal scraps by chemical composition analysis. In this work, a method for intensity-ratio-based LIBS classification of stainless steel applicable to highly fluctuating LIBS signal conditions is proposed. The spectral line pairs for intensity ratio calculation were selected on the consideration of elemental concentration and upper levels of emission lines. It is demonstrated that the classification accuracy can be significantly improved from that of full spectra principal component analysis or intensity-based analysis. The proposed method is considered to be suited for an industrial scrap sorting system that requires minimal maintenance and low system price.
关键词： intensity ratio,laser-induced breakdown spectroscopy (LIBS),stainless steel,classification
更新于2025-09-19 17:13:59
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Collaborative Optimization of Density and Surface Roughness of 316L Stainless Steel in Selective Laser Melting
摘要： Although the concept of additive manufacturing has been proposed for several decades, momentum in the area of selective laser melting (SLM) is ?nally starting to build. In SLM, density and surface roughness, as the important quality indexes of SLMed parts, are dependent on the processing parameters. However, there are few studies on their collaborative optimization during SLM to obtain high relative density and low surface roughness simultaneously in the literature. In this work, the response surface method was adopted to study the in?uences of di?erent processing parameters (laser power, scanning speed and hatch space) on density and surface roughness of 316L stainless steel parts fabricated by SLM. A statistical relationship model between processing parameters and manufacturing quality is established. A multi-objective collaborative optimization strategy considering both density and surface roughness is proposed. The experimental results show that the main e?ects of processing parameters on the density and surface roughness are similar. We observed that the laser power and scanning speed signi?cantly a?ected the above objective quality, but the in?uence of the hatch spacing was comparatively low. Based on the above optimization, 316L stainless steel parts with excellent surface roughness and relative density can be obtained by SLM with optimized processing parameters.
关键词： 316L stainless steel,multi-objective optimization,relative density,selective laser melting,surface roughness
更新于2025-09-19 17:13:59
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Fatigue Life Behavior of Laser Shock Peened Duplex Stainless Steel with Different Samples Geometry
摘要： Two different stress raiser geometries (fillet and notched) were treated by laser shock peening (LSP) in order to analyze the effect of sample geometry on fatigue behavior of 2205 duplex stainless steel (DSS). The LSP treatment was carried through Nd:YAG pulsed laser with 1064 nm wavelength, 10 Hz frequency, and 0.85 J/pulse. Experimental and MEF simulation results of residual stress distribution after LSP were assessed by hole drilling method and ABAQUS/EXPLICIT software, respectively. The fatigue tests (tensile-tensile axial stress) were realized with stress ratio of R = 0.1 and 20 Hz. A good comparison of residual stress simulation and experimental data was observed. The results reveal that the fatigue life is increased by LSP treatment in the notched samples, while it decreases in the fillet samples. This is related to the residual stress distribution after LSP that is generated in each geometry type. In addition, the fatigue crack growth direction is changed according to geometry type. Both the propagation direction of fatigue crack and the anisotropy of this steel results detrimental in fillet samples, decreasing the number of cycles to the fatigue crack initiation. It is demonstrated that the LSP effect on fatigue performance is influenced by the specimen geometry.
关键词： laser shock peening,residual stress,duplex stainless steel,fatigue life,sample geometry
更新于2025-09-19 17:13:59
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Laser Brazing of Dissimilar Joint of Austenitic Stainless Steel and Pure Copper
摘要： In many industries, there are applications that require the joining of stainless steel and copper components; therefore, the welding of dissimilar stainless steel/copper joints is a common process. For this investigation, the optimal brazing conditions and suitable filler metals for laser brazing of stainless steel/copper lap joints were studied. Tensile shear force increases with increases in the laser spot diameter or in the laser irradiation angle, which is associated with increased bonding width; however, as bonding width approaches 2 mm, tensile shear force reaches a saturated value due to fracturing at the HAZ of the Cu base plate. In order to obtain joints with high tensile shear strength, laser brazing was optimized by using Cu-Si-based filler metal under the following conditions: laser power: 4 kW; spot diameter: 3mm; laser irradiation angle: 80 degrees; irradiation position shift: 0.6 mm; brazing speed: 0.30 m/min; and filler metal feed speed: 0.30 min. Concerning filler metals, it was found that the Ni-Cu type showed relatively large tensile shear force even at high welding speeds in comparison with those of the Cu-Si, Cu, Cu-Ni, Ni-Cu and Ni types, respectively.
关键词： Laser brazing,Copper,Filler metal,Dissimilar material,Stainless steel,Brazing condition
更新于2025-09-16 10:30:52
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Structurally colored stainless steel processed by using femtosecond laser pulses
摘要： Structurally colored stainless steel (SS) surfaces were produced by using femtosecond laser at normal incidence at ambient conditions. The influence of laser polarization on the surface properties was investigated. The surface morphologies, roughness and color of the laser-treated surface were characterized by using environmental scanning electron microscope (ESEM), roughmeter and atomic force microscope (AFM). Results indicated that the circular polarization leads to more random structures than the horizontally linear polarization. Specimen with the highest surface roughness shows the brightest color. Different colors are cyclically exhibited by changing view angles due to different orders of diffraction. This investigation developed the technique of using femtosecond laser in situ preparation of periodic structures on 304 SS, and indicating that laser polarization is an important parameter to control surface structures to achieve different colors.
关键词： polarization,micro/nanostructure,coloration,Femtosecond laser,stainless steel
更新于2025-09-16 10:30:52
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[Laser Institute of America ICALEO? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22–26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Laser metal deposition with 316L stainless wire: Macro morphologies and microstructures
摘要： Laser metal deposition (LMD) with wire as the filler material has demonstrated to be a potential method in addictive manufacturing due to its higher material deposition efficiency, improved surface quality, reduced material wastage and cleaner process environment without metal dust pollution. In this study, single beads samples and block samples of 316L stainless wire were successfully deposited on the surface of 316L stainless steel under optimized depositing conditions using a YLR-4000 S2 CW Fiber Laser, a Fronius MAG arc welding machine and an ABB industrial robot. The macro morphologies, geometric characteristics and microstructures were examined. The influence of process parameters to macro morphologies and geometric characteristics of different samples were carefully studied. A 5*5 block sample was finally deposited with appropriate parameters based on the single bead experiments. The results showed that satisfied single bead samples with smooth surface and high aspect ratio (height-width ratio) can be deposited under appropriate process conditions and parameters during the stable deposit process. Uniform structures of fine equiaxed austenite grains with good metallurgical bonding to the substrate were also obtained. Uniform bond-like microstructures of block samples was also obtained and investigated. All these results will provide guidance for further large study of laser metal-wire deposition with structures.
关键词： Laser metal deposition,macro morphology,geometric characteristic,316L stainless wire,microstructure
更新于2025-09-16 10:30:52
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Multi Response Optimization of Nd:YAG Laser Micro Drilling Characteristics of 304 Stainless Steel using Desirability Function Approach
摘要： Laser micro drilling is a non-traditional machining process for producing micro hole of various sizes and different angle in many modern industrial application, such as aerospace gas turbine, automobile industry, electronics field etc. Laser drilling is extremely high speed with high aspect ratio. However, the quality and accuracy of the holes can be excellent, if the optimal process parameter has set. It is difficult to achieve exact size of hole as per suggested by the equipment manufacturer without any consideration. So this paper addressed to investigate influence of process parameter on drilling characteristics of 304 stainless steel of 1.5 mm thickness material using Nd:YAG laser drilling through desirability function optimization technique. The effect of process parameter taken during machining operation is average power, nozzle stand-off, nitrogen gas pressure to obtain requisite hole quality. The output responses are entry circularity, exit circularity and taper angle were considered performance criteria for the experimentation. Analysis of variance (ANOVA) has been performed to find out the significant process parameter during the micro drilling process. It is found that nitrogen gas pressure is highly influencing factor on the overall response characteristics, which is about 54.62% and nozzle standoff is 2nd highest influencing parameter, which is about 27.69%.
关键词： 304 Stainless Steel,Laser Drilling Machine,Optimization,Desirability,ANOVA
更新于2025-09-16 10:30:52
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Characterisation of 17-4PH metallic powder recycling to optimise the performance of the selective laser melting process
摘要： The advantages of Additive Manufacturing (AM) processes are well known. Particularly, those AM techniques which are used to manufacture metallic parts are of great interest to industry due to the good mechanical behaviour of metallic alloys. Despite this, the quality of the manufactured parts is still an important issue due to the wide range of parameters that can affect them. In some powder bed fusion techniques, such as Selective Laser Melting (SLM), not all the initially distributed metallic powder is used in the process. There is an unmolten portion that can be recycled to ensure both the economic and environmental viability of the process. Even though this powder is unmolten, it is thermally affected due to the high temperatures attained during the process. This fact affects the powder properties and, consequently, the properties of the manufactured parts. Therefore, an analysis of the recycling effects of SLM metallic powders is an important issue in order to establish good recycling procedures and to optimise the process performance.
关键词： Additive manufacturing,17-4PH stainless steel,Powder bed fusion,Selective laser melting,Laser beam melting
更新于2025-09-16 10:30:52
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Nd:YAG laser welding of dissimilar metals of titanium alloy to stainless steel without filler metal based on a hybrid connection mechanism
摘要： In this paper, Nd:YAG laser welding of TC4 Titanium (Ti) alloy and SUS301 L stainless steel (SS) dissimilar metal material was carried out without filler metal by laser biasing. The microstructure and fracture mode of the joint were analyzed by scanning electron microscope (SEM), energy dispersive instrument (EDS), and X-ray diffractometer (XRD). The mechanical properties of the joint were evaluated by a tensile test. The results showed that when the peak temperature was 1116?, the liquid phase existed only in the narrower region of the Ti-SS interface, and the eutectic reaction zone formed a reaction layer, which was mainly composed of (cid:2)-Ti solid solution. Ti-Fe intermetallic compound (TiFe, TiFe2) was formed at the Ti alloy-SS interface by heat conduction of the unmelted Ti alloy. The TEM analysis confirmed the presence of the (cid:2)-Ti and TiFe2 phases. The nucleation and growth of the reaction layer depended on the diffusion rate and atomic concentration of Ti and Fe atoms. The growth of the reaction layer could be effectively promoted by increasing the welding heat input, increasing the peak temperature of the Ti-SS interface and prolonging the reaction time. The tensile strength of the joint could be reached 336 MPa and an elongation was 0.13 %. The eutectic reaction method could control the thickness and size of the Ti-Fe intermetallic compound at the interface of the Ti alloy-SS and improve the mechanical properties of the joint.
关键词： Reaction layer,Microstructure,Mechanical property,SUS301L stainless steel,TC4 Ti alloy,Eutectic reaction
更新于2025-09-16 10:30:52
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[Laser Institute of America ICALEO? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18–22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Hot wire laser cladding for repairing martensite precipitation hardening stainless steel
摘要： Martensite precipitation hardening stainless steel (M-PHSS) is widely used as load-bearing parts because of its excellent overall properties. It is economical and flexible to repair the failure parts instead of changing new ones. However, it is difficult to keep the properties of repaired layer as good as the substrate. Multi-pass layers were cladded on the surface of FV520B by hot wire laser cladding. Response surface methodology (RSM) was used to optimize processing parameters and predict formation quality of multi-pass cladding. Microstructure of the as-cladded layer was non-uniform and divided into quenched and tempered region. For the as-cladded layer, tensile strength was almost equivalent to that of the substrate, while ductility and impact toughness deteriorated much. With using laser scanning, microstructure of the clad layers was tempered to fine martensite uniformly. The ductility and toughness of clad layer were improved to be equivalent to those of the substrate, while the tensile strength was a little lower than that of the substrate. By adding TiC nanoparticles as well as laser scanning, the precipitation strengthening effect was improved and the structure was refined in the clad layer. As a result, the strength, ductility and toughness were all improved further. Finally, high quality clad layers were obtained with equivalent or even superior mechanical properties to the substrate, offering a valuable technique to repair M-PHSS.
关键词： Mechanical properties,Microstructure,Hot wire laser cladding,Martensite precipitation hardening stainless steel,Repair
更新于2025-09-16 10:30:52