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In situ chemical composition analysis of a tungsten-inert-gas austenitic stainless steel weld measured by laser-induced breakdown spectroscopy
摘要： The chemical composition of a weld metal determines the resulting solidification mode of stainless steel and the consequent weld metal quality. In this work tungsten inert gas (TIG) welding of EN grade 1.4435 austenitic stainless steel was monitored using laser-induced breakdown spectroscopy (LIBS) for the in situ measurement of chemical composition changes. This research aims to prototype a real-time chemical composition analysis system for welding applications and prove the feasibility of such quality control loop. LIBS was used to investigate in situ the monitoring of metal vaporization during TIG welding. We found Mn vapor formation above the weld pool and subsequent condensation of Mn on the weld metal surface using LIBS. Post-weld line scans were conducted by LIBS on various welds produced with different welding currents. Local changes of Ni and Mn were observed at higher welding currents. The results are in good agreement with the literature and proved that LIBS can be used in situ to inspect the TIG welding process.
关键词： LIBS,In situ measurement,Metal vapor,Welding,Austenitic stainless steel
更新于2025-09-23 15:19:57
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[IEEE 2019 Sixteenth International Conference on Wireless and Optical Communication Networks (WOCN) - Bhopal, India (2019.12.19-2019.12.21)] 2019 Sixteenth International Conference on Wireless and Optical Communication Networks (WOCN) - Palm print Recognition Using Neighboring Direction Indicator
摘要： An electroless plating of Co–Ni–P was applied to a grain-oriented electrical steel substrate, resulting in a power loss improvement of ～9%–11%. The mean thickness of the coating was found to be 2.15 ± 0.15 μm from environmental scanning electron microscopy images. Shifts of the magnetostriction stress sensitivity curves showed that stress was acting on the substrate and was corroborated by a shift in X-ray diffraction (XRD) peaks and narrowing of the domains after the samples were coated. The magnetic property measurement system results con?rmed the magnetic nature of the coating and XRD results showed peaks of α-iron in the uncoated sample, α-iron-cobalt and α-iron in the Co-Ni-P-coated sample. The Talysurf pro?lometer showed a decrease in surface roughness values after coating the sample, which reduced the hysteresis loss.
关键词： magnetic coating,power loss,grain-oriented electrical steel,stress,Electroless coating,magnetostriction
更新于2025-09-23 15:19:57
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Laser-arc hybrid additive manufacturing of stainless steel with beam oscillation
摘要： A novel additive manufacturing approach integrating an oscillating laser beam and a cold metal transfer arc was developed to balance the surface accuracy, deposition efficiency, and mechanical properties of the deposited parts. The new method was termed as oscillating laser-arc hybrid additive manufacturing (O-LHAM). The sample properties of the wire-arc additive manufacturing (WAAM), laser-arc hybrid additive manufacturing (LHAM), and O-LHAM processes were compared. It was found that some new phenomena were induced by beam oscillation. First, both the surface roughness and minimum processing margin of the O-LHAM sample were reduced to 20% of the WAAM sample, because the droplet transfer was stabilized by the laser-arc synergic effects. Second, the grains were refined, and the {001} <100>-cube texture content was decreased to 1.6%, as the oscillation induced a strong stirring effect on the molten pool. The nondestructive X-ray test suggested that the visible porosity within the O-LHAM sample was suppressed by beam oscillation when the periodically oscillated laser keyhole could “capture” the bubbles, while the porosity within the LHAM sample reached 24%. Due to the microstructure changes and the porosity suppression, the O-LHAM almost eliminated the anisotropy of tensile strength and improved the elongation by up to 34%.
关键词： Oscillating beam,Tensile properties,Additive manufacturing,Stainless steel
更新于2025-09-23 15:19:57
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Laser cutting optimization model with constraints: Maximization of material removal rate in CO <sub/>2</sub> laser cutting of mild steel
摘要： Taking full advantage of what laser cutting technology offers in terms of achieving superb quality cuts at low cost and high production rates requires the optimization of laser cutting parameters. This implies the need to formulate and solve different laser cutting optimization problems. In this article, an optimization model for CO2 laser cutting of mild steel is developed. The laser cutting optimization problem was explicitly formulated as a single-objective optimization problem with five non-linear constraints of the equality, inequality and range type. The goal was to determine the laser cutting parameter values so as to maximize the material removal rate while simultaneously considering practical process constraints related to dross formation, kerf width, perpendicularity deviation, surface roughness and severance energy. Two crossed experimental designs of different resolutions were performed in order to define six mathematical models, which were used in the formulation of the optimization problem. For the purpose of optimization, the exhaustive iterative search algorithm was applied, since it determines solutions whose optimality is guaranteed in the given discrete space of input variable values. The practical usability of the developed laser cutting optimization model and the effectiveness of the applied optimization approach were proved while solving a real case study aimed at the optimization of laser cutting parameters for cutting parts for the furnace industry.
关键词： mild steel,CO2 laser cutting,optimization model,material removal rate,non-linear constraints
更新于2025-09-23 15:19:57
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Influence of the pulse duration at near-infrared wavelengths on the laser-induced material removal of hot-dipped galvanized steel
摘要： Hot-dipped galvanized steel is processed with short- and ultrashort-pulsed lasers in air at near-infrared wavelengths with pulse durations ranging from 350 fs to 241 ns. The morphology of the ablated craters (processed over a range of laser fluence levels and a number of laser pulses) is analyzed by confocal laser scanning microscopy and scanning electron microscopy. The ablation threshold of galvanized steel is found to increase with laser pulse durations following a simple power Fth ? A:τB law. Longer pulse durations in the nanosecond regime, as compared to pulse durations in the picosecond and femtosecond regime, result in higher ablation efficiency and energy penetration depth at the cost of surface quality.
关键词： ablation efficiency,ultrashort-pulsed laser,galvanized steel,ablation threshold,rim
更新于2025-09-23 15:19:57
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Investigation on the effect of power and velocity of laser beam welding on the butt weld joint on TRIP steel
摘要： In this study, the characterization of laser weld joint on transformation-induced plasticity (TRIP) steel sheets coupled with Nd:YAG laser welding was investigated, and the influence of welding conditions like angle of weld, power of laser, and welding speed on the strength of the joint was measured. The microstructure, tensile behavior, and microhardness of TRIP laser-welded sheets were examined in detail. The power was maintained constant, i.e., 1800 W, and by relatively varying the velocity from 25 to 30 mm/s, the strength of the joint increased drastically to 11%. In contrast, by varying the power, the effect of velocity was reduced; however, the point performance was enormously stable. Finally, the microhardness behavior of the heat-affected zone and fusion zone was investigated and discussed.
关键词： butt weld joint,heat treatment,TRIP steel,Nd:YAG laser,laser welding
更新于2025-09-23 15:19:57
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Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review
摘要： Martensitic stainless steels are widely used in industries due to their high strength and good corrosion resistance performance. Precipitation-hardened (PH) martensitic stainless steels feature very high strength compared with other stainless steels, around 3-4 times the strength of austenitic stainless steels such as 304 and 316. However, the poor workability due to the high strength and hardness induced by precipitation hardening limits the extensive utilization of PH stainless steels as structural components of complex shapes. Laser powder bed fusion (L-PBF) is an attractive additive manufacturing technology, which not only exhibits the advantages of producing complex and precise parts with a short lead time, but also avoids or reduces the subsequent machining process. In this review, the microstructures of martensitic stainless steels in the as-built state, as well as the effects of process parameters, building atmosphere, and heat treatments on the microstructures, are reviewed. Then, the characteristics of defects in the as-built state and the causes are specifically analyzed. Afterward, the effect of process parameters and heat treatment conditions on mechanical properties are summarized and reviewed. Finally, the remaining issues and suggestions on future research on L-PBF of martensitic precipitation-hardened stainless steels are put forward.
关键词： 17–4 stainless steel,heat treatment,microstructure,precipitation-hardened stainless steels,ferrite,selective laser melting,building atmosphere,defects,laser powder bed fusion
更新于2025-09-23 15:19:57
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Laser hardening of copper-iron pseudoalloy
摘要： The purpose of the study is to improve the performance characteristics of powder pseudo-alloy materials using surface heat treatment. Such materials have unique properties, for example, self-lubrication under dry friction conditions, high thermal conductivity coefficient, and high electro-erosion resistance. The disadvantage of powder pseudo-alloys is their relatively low strength. The paper considers the method of surface hardening by high-energy treatment - laser radiation. The paper describes the method of experimental research, describes the method of obtaining powder material, its chemical composition, shows the equipment used. The results of studies of the microstructure and microhardness of the surface layer of steel-copper powder pseudo-alloy after laser heat treatment (LHT) of a continuous-wave fiber laser with a maximum power of 1 kW are given, LHT modes are indicated, the influence of LHT parameters on the characteristics of the hardened layer is evaluated. It is revealed that the partial melting region in which melting occurs in the volumes of the fusible component (copper) in the initial structure and contacting segments of steel matrix is formed in the material in addition to the total melting zone. Then the quenching zone from the solid state follows, in which the maximal hardness up to 1000 HV is attained for best samples in the volume of martensite, which is formed in perlite colonies of the initial steel–copper material.
关键词： Steel–copper pseudoalloy,Microhardness,Abrasive wear,Laser heat treatment,Powder metallurgy,Microstructure
更新于2025-09-23 15:19:57
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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 18a??22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Preliminary laser welding tests of 22MnB5 steel with a butt joint and lap joint configurations
摘要： In recent years, the automotive industry has expanded the use of hot stamping and press hardening processes. Using ultra-high-strength steels, such as 22MnB5, allows car manufacturers to build lighter, stronger and safer vehicles at a reduced cost and generate lower CO2 emissions. In the research the laser weldability of 22MnB5 steel was tested. The test plates were produced using a constant heating temperature of 900°C and a variable furnace time of between 250 and 600 seconds. The samples were quenched in a water-cooled flat die to ensure a fully martensitic structure and good flatness. The welding tests were made using a 10 kW disk laser equipped with the optics of Precitec. Various welding energies were used to determine the effects of heating and cooling on the mechanical properties of the welds. The weld inspections conformed to ISO standard 13919-1 and automotive testing code SEP 1220-3 (Testing and documentation guideline for the joinability of thin sheet of steel - Part 3: Laser beam welding) where applicable. The radiographic inspection showed some porosity and a lack of penetration on both the face and root side of almost every weld. Despite these serious imperfections, the destructive tests were performed and showed relatively good results. The maximum achieved yield strength was over 1200 MPa, reaching almost the strength of the base material 22MnB5. The maximum value of hardness in the laser welds of 22MnB5 steel was 500 HV; the same as the hardness of the base material. However, a relatively narrow softened zone exists in the HAZ area, which has a hardness value of 200 HV.
关键词： press hardening,ultra-high-strength steels,22MnB5 steel,automotive industry,laser welding
更新于2025-09-23 15:19:57
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Comparative study of optimised molybdenum back-contact deposition with different barriers (Ti, ZnO) on stainless steel substrate for flexible solar cell application
摘要： In this study, we optimised the molybdenum (Mo) back-contact layer for solar cell applications on stainless steel substrates using direct-current (dc) sputtering with varying sputtering powers (100 W to 500 W) and pressures (5 mTorr to 20 mTorr). We comparatively analysed the effectiveness of titanium (Ti) layer deposited using e-beam evaporation deposition and zinc oxide (ZnO) layer deposited using radio-frequency (RF) sputtering for barrier application with Mo. Structural characterisation of the optimised Mo films was carried out using XRD studies confirmed the (110) plane corresponding to the body-centred cubic (bcc) structure. Estimated Mo film parameters for films deposited on barrier layers were compared against films deposited on SS substrate without any barriers as these properties influence the prospective diffusion of Fe and Cr into the absorber layer. Surface characterisation of the deposited films was carried out using a scanning electron microscopy (SEM) to study the morphology of films, and energy-dispersive X-ray (EDX) to identify elemental presence to confirm the blockage of the impurities atoms through the film. Secondary ion mass spectroscopy (SIMS) was employed to study the depth profiles of films while atomic force microscopy (AFM) was used to characterise the topographical properties from the sputtered Mo film and analyse the grain properties of the films. A low resistivity value of 0.511 × 10–6 Ω m for Mo films on the reference glass substrate and 0.625 × 10–6 Ω m for the Mo film on ZnO barrier was measured using the four-point probe. We observed a further 40% reduction in impurities using annealed ZnO barrier combined with an optimised Mo layer.
关键词： flexible solar cell,stainless steel substrate,sputtering,barrier layers,molybdenum back-contact
更新于2025-09-23 15:19:57