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Experimental and Numerical Investigation of Surface Texturing 316L Stainless Steel by Laser Shock Processing
摘要： Surface texturing is considered as a promising method to reduce friction coefficient and improve wear resistance of frictional pairs. In this study, laser peen texturing (LPT) based on laser shock process is proposed to fabricate dimple array on 316L stainless steel. LTP experiments are carried out to investigate the geometrical characteristics of the micro-dimple. It is shown that LPT is capable of fabricating micro-dimples with good repeatability. Numerical simulation based on finite element method is conducted to further study the process of LPT. It is found that the dimple depth obtained from numerical simulation shows a good agreement with that measured from experiments. Moreover, by means of stress analysis, it is shown that residual compressive stress exists in the specimen, which is supposed to be helpful to improve the triboligical performance of frictional pairs.
关键词： friction reduction,wear resistance,316L stainless steel,surface texturing,laser shock processing
更新于2025-09-11 14:15:04
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Defect Prevention in Selective Laser Melting Components: Compositional and Process Effects
摘要： A model to predict the conditions for printability is presented. The model focuses on crack prevention, as well as on avoiding the formation of defects such as keyholes, balls and lack of fusion. Crack prevention is ensured by controlling the solidi?cation temperature range and path, as well as via quantifying its ability to resist thermal stresses upon solidi?cation. Defect formation prevention is ensured by controlling the melt pool geometry and by taking into consideration the melting properties. The model’s core relies on thermodynamics and physical analysis to ensure optimal printability, and in turn offers key information for alloy design and selective laser melting process control. The model is shown to describe accurately defect formation of 316L austenitic stainless steels reported in the literature.
关键词： additive manufacturing,solidi?cation cracking,austenitic stainless steel,porosity
更新于2025-09-11 14:15:04
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Localized Changes of Stainless Steel Powder Characteristics During Selective Laser Melting Additive Manufacturing
摘要： In laser powder bed additive manufacturing processes, feedstock materials are often recycled after each build. Currently, a knowledge gap exists regarding powder reuse effects on powder size distribution, morphology, and chemistry as a function of part geometry and processing conditions. It was found during selective laser melting (SLM) of 316 stainless steel that a significant amount of (0.100 wt pct) oxygen pickup can occur in molten material (spatter) ejected from the powder bed surface. This value was significantly larger than the oxygen content of the powders in the heat-affected-zone regions, adjacent to molten pool, also exhibit oxygen pickup (? 0.043 wt pct). The oxygen content in unmelted 316L powder was found to vary as a function of its spatial position in the powder bed, relative to the heat source. Interestingly, the volume of melted material (i.e., thin vs thick walls) did not correlate well with the extent of oxygen pickup. Possible mechanisms for oxygen pickup in the powder during SLM, such as adsorption and breakdown of water, oxygen solubility, spatter re-introduction, and solid-state oxide growth, are discussed.
关键词： Oxygen Pickup,Selective Laser Melting,Powder Reuse,Additive Manufacturing,Stainless Steel
更新于2025-09-11 14:15:04
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An experimental investigation of the effects of diode laser surface hardening of AISI 410 stainless steel and comparison with furnace hardening heat treatment
摘要： This study investigated the ability of the continuous wave diode laser surface hardening of AISI 410 martensitic stainless steel with a maximum power of 1600 W. Variable process parameters scanning speed (4–7 mm/s), laser power (1200–1600 W) and stand-off distance (65–75 mm) were considered in this study. Microhardness, the geometry of hardened layer (depth and width), microhardness deviation from the base metal microhardness (MHD), microstructure analysis of the laser-hardened zone through optical microscopy and field emission scanning electron microscopy and percentage of the ferrite phase in AISI 410 microstructure by using Clemex software were considered as process output responses. Results confirmed that by increasing the laser power and reducing the scanning speed, the surface hardness and the depth of hardness increase. It is also revealed the width of the hardened area increases by enhancing stand-off distance and reducing the laser power. Maximum hardness of 630 HV0.3 with 2.2 mm depth is obtained. Also, the furnace hardening heat treatment is compared with the laser hardening process. Microstructure, microhardness, and impact tests of the two processes are compared. Results showed that the hardness of the diode laser is 1.4 times the hardness of the furnace hardening heat treatment.
关键词： Microhardness deviation,Microhardness,AISI 410 martensitic stainless steel,Laser surface hardening,Diode laser
更新于2025-09-11 14:15:04
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Parametric optimization of pulsed laser ablation on stainless steel for improving corrosion resistance by Taguchi method
摘要： In the present study, pulsed laser ablation in liquid (PLAL) treatment has been optimised for the corrosion resistance of stainless steel in neutral solution; the overlap rate is the most optimized laser parameters obtained implementing the Taguchi method has been verified experimentally and hence supporting the accuracy of optimization of laser parameters under of Variance (ANOVA) and signal to noise ratio are used to analyse the effect of different laser parameters on the responses. The laser irradiation power is the most dominant factors affecting been derived by considering the response which is corrosion potential of metal targets. Analysis out using fiber laser source by varying laser parameters include overlap rate, scanning speed, ASTM 304/2B stainless steel using Taguchi method. PLAL experimental trials were carried laser irradiation power and the number of laser pulses. The optimum laser parameters have significant impact corrosion resistance of metal in acidic solution. The responses of the the given set of experimental conditions.
关键词： corrosion behavior,PLAL,Surface modification,Taguchi method,fiber laser,stainless steel
更新于2025-09-11 14:15:04
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Some insights into the structure and morphology of surfactant-doped poly(o-toluidine)
摘要： Poly(o- toluidine) (POT) doped with dodecylbenzene sulfonic acid (DBSA) was synthesized by inverse emulsion polymerization and characterized systematically for morphological, structural, electrochemical, and thermal properties with scanning electron microscopy (SEM), cyclic voltammetry (CV), X- ray diffraction (XRD), and thermogravimetric analysis (TGA). SEM demonstrated irregular granular morphology of the polymer with high porosity similar to polyaniline (PANI). The size distribution of POT salts was analyzed using Nano Measurer 1.2.5 software from scanning electron micrographs. The semicrystalline nature, with crystallite size and d- spacing in the range of 21.4–30.2 nm and 4.93–4.99 ?, respectively, was confirmed from XRD. The activation energy (Ea) of degradation was calculated from TGA curves using Coats and Redfern (39.92–47.50 kJ/mol) & Horwitz and Metzger (50.09 ? 57.45 kJ/mol) methods, respectively. The small crystallite size, high thermal stability, and high values of the activation energy of degradation reveal that DBSA is an efficient dopant for POT and imparts interesting characteristics to this otherwise less thermally stable polymer. The fast rate of electron transfer of POT, as confirmed by electrochemical impedance spectroscopy, reveals its high electrochemical activity toward electrolyte. Potentiodynamic polarization measurement of POT- coated stainless steel showed large anodic potential shift as compared to uncoated stainless steel, illustrated good anticorrosion performance. The enhanced anticorrosion performance is due to synergic effect of dopant which increases the contortion of diffusion pathway of corrosive substance.
关键词： thermogravimetric analysis,cyclic voltammetry,stainless steel,poly(o-toluidine)-doped with dodecylbenzene sulfonic acid,X-ray diffraction,activation energy,anticorrosion
更新于2025-09-10 09:29:36
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Surface micro-structuring of type 304 stainless steel by femtosecond pulsed laser: effect on surface wettability and corrosion resistance
摘要： This paper presents results on femtosecond (fs) pulsed laser-based surface micro-structuring of type 304 stainless steel (304 SS). Post laser treatment surface wettability and corrosion resistance investigation are reported. SS sample surfaces have been micro-structured using a typical laser fluence of ~ 0.9 J/cm2 for varying sample scanning speed in the range 25–1000 μm/s. Dense array of micro-protrusions have been generated without formation of a crater for an optimized target scan speed exceeding 200 μm/s. Static water contact angle (WCA) measurement indicated super-hydrophilic behavior immediately after laser treatment. However, hydrophilicity (wettability) was found to decrease with storage time with sample becoming highly hydrophobic (WCA: 144° ± 5°) within 50 days after laser treatment. Corrosion resistance of the laser-treated samples was measured by potentio-dynamic polarization technique. Fs laser micro-structured SS has shown poorer corrosion resistance in comparison to pristine surface. Observed poorer corrosion resistance of laser-treated surface has been explained on the basis of surface chemical composition and surface roughness. The results demonstrated that corrosion resistance increased with increasing hydrophobicity of the SS surface.
关键词： corrosion resistance,femtosecond pulsed laser,stainless steel,surface micro-structuring,wettability
更新于2025-09-10 09:29:36
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Assessment of the Microstructure and Mechanical Properties of a Laser-Joined Carbon Fiber-Reinforced Thermosetting Plastic and Stainless Steel
摘要： The thermosetting plastic and stainless steel were joined with a fiber laser. The influence of processing parameters on the joint was studied. The laser scanning on stainless steel is shown to result lathy ferrite precipitates along the boundary, which modifies austenite, while in the second zone, ferrite forms the skeleton structure and separates austenite into a small cellular structure. The laser joining improves the microstructure of both zones. With an increase in the laser scanning speed and power, the shear strength of the stainless steel/plastic joint first increases and then decreases. A low laser scanning speed or high laser power would overheat polyphenylene sulphide and lead to its decomposition. Those factors would also reduce heat transfer and lead to its insufficient melting. The stainless steel/plastic joint acquires a maximum shear strength at a laser scanning speed of 4–5 mm/s and laser power of 320-350 W.
关键词： bonding interface,laser joining,microstructure,carbon fiber-reinforced thermoplastic,stainless steel,shear strength
更新于2025-09-10 09:29:36
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NOVEL MATRIX SUBLIMATION DEVICE FOR MALDI MASS SPECTROMETRY IMAGING
摘要： Sublimation is a widely used method for matrix deposition in imaging mass spectrometry experiments. Still, most of the time standard glass sublimators are used for this purpose, which do not enable optimal matrix deposition reproducibility, compromising inter-experiment comparison of the results. Here we present an in-house designed stainless steel sublimator in which the parameters that have the strongest influence over matrix deposition reproducibility can be easily monitored. Using sections of human colon biopsies we demonstrate the capabilities of this new prototype.
关键词： mass spectrometry imaging,matrix sublimation,stainless steel sublimator,reproducibility,MALDI
更新于2025-09-09 09:28:46