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Experimental investigation on Ytterbium fiber laser butt welding of Inconel 625 and Duplex stainless steel 2205 thin sheets
摘要： In this study, welding of Superalloy Inconel 625 and duplex stainless steel 2205 (DSS 2205) has been successfully performed through Ytterbium fiber laser at different heat inputs. With decreasing energy input, width of the weld bead narrowed and the mechanical properties of the joint improved. Characterization of the weld joint was carried out using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and micro-hardness testing. No solidification cracks or porosity was observed in the microstructure of the weld metal (WM). Cellular dendritic and columnar dendritic grains were main grain types observed in the weld metal. At heat input of 43 J/mm, inter-dendritic arms of the weld metal witnessed more segregation of Molybdenum and Niobium in comparison of welded samples at heat input of 21.5 J/mm. Carbides of Cr, Mo and Ni are formed in the weld joint interface as revealed by the XRD analysis. Tensile strength study reveals the maximum strength of 890 MPa when the heat supplied is low i.e. 21.5 J/mm. This strength value is more than that of the base metal (DSS 2205). The result obtained in terms of comprehensive structure-property correlation, recommends the effectiveness of laser beam welding for joining of the said dissimilar alloys.
关键词： Mechanical properties,Laser beam welding,Duplex stainless steel 2205,Microstructure,Inconel 625
更新于2025-09-23 15:19:57
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Electrodeposition of hierarchical zinc oxide nanostructures on metal meshes as photoanodes for flexible dye-sensitized solar cells
摘要： Hierarchical zinc oxide (ZnO) nanorod arrays (ZNRAs) were fabricated on stainless steel meshes via a two-step electrodeposition approach as flexible dye-sensitized solar cells (DSSCs) photoanodes. The two-step electrodeposition was realized by deposition of primary ZNRAs followed by growth of secondary branched ZnO nanorods on the primary ZnO nanorods surfaces. The morphologies of ZNRAs and the photovoltaic performances of the assembled DSSCs with different deposition conditions of primary ZNRAs were compared in detail. After modulating electrodeposition conditions, the DSSC assembled with hierarchical ZNRAs obtained an optimum photovoltaic performance with power conversion efficiency of 1.81 %.
关键词： Electrodeposition,Zinc oxide,Stainless steel mesh,Dye-sensitized solar cells,Flexible photovoltaic devices
更新于2025-09-23 15:19:57
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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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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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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
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Study of Microstructure and Properties of 316L with Selective Laser Melting Based on Multivariate Interaction Influence
摘要： The selective laser melting technique is widely used in aerospace and biomedical industries, and the performance of formed 316L parts is significantly subject to the forming angle. As the selective laser melting 316L parts are constrained by multiple performance indexes, the study involves multivariate interaction influenced on the forming parameters such as the angle with the xz plane, the angle with the xy plane, laser power, scan speed, powder thickness, and hatching space on the indexes like tensile strength, density, and surface roughness with linear regression equations based on multiobjective optimization to obtain the best process parameters. The study results of microstructure performance of the formed 316L parts show that the angle with the xz plane has significant effect on the experiment indexes, while the layer thickness has the greatest effect on the indexes. After stretching, the molten pools are obviously elongated and the microstructure of the formed 316L parts is composed of equiaxed crystals and columnar crystals with a grain width of 0.28–0.4 nm. The secondary growth of the dendrites is not obvious, and the crystallinity of the selective laser melting 316L parts is not as good as the standard parts, with the microstructure showing directional solidification due to grain refinement and microscopic distortion of crystals. As the fracture has dimples, it is a ductile fracture and typical plastic fracture. The hardness near the fracture is higher than that of the substrate, whilst the indexes regarding the selective laser melting parts are higher than the ASTM-A182 and ASTM-F3184-16 standards. Since the theoretical model built in this study has less error, the findings have practical engineering application value.
关键词： microstructure,multivariate interaction,selective laser melting,mechanical properties,316L stainless steel
更新于2025-09-23 15:19:57
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A comparative study of microstructure and hydrogen embrittlement of selective laser melted and wrought 17a??4??PH stainless steel
摘要： In this study, the microstructure and hydrogen embrittlement of 17–4 PH stainless steel produced by Selective Laser Melting (SLM) were investigated. The microstructure of SLM-ed 17–4 PH stainless steel was found to be fully ferritic, in contrast to the wrought martensitic steel. This finding was correlated to the high cooling and heating rates of the SLM process that suppressed the austenite formation and retained the delta ferrite to room temperature. The SLM-ed steel shows grains elongated in the building direction and its grain size is higher than the prior austenitic grain size of the wrought steel. The two steels present nanoscale copper precipitation after ageing 4 h at 580°C. The yield strength of the SLM-ed steel was found lower by only 10% with respect to the wrought steel. The hydrogen embrittlement was evaluated by performing slow strain rate tensile tests under cathodic charging after ageing 4 h at 580°C. It was found that SLM-ed 17–4 PH steel was more susceptible to hydrogen embrittlement compared to its wrought counterpart. This was attributed to the difference in microstructures, more specifically grain size. The crack initiation and propagation was much easier in the ferritic SLM-ed steel than in the martensitic wrought steel because of the higher grain size. The fracture in both steels was due to a significant subcritical crack growth followed by fast overload fracture of the remaining ligament. The fracture surface of the wrought steel showed a brittle intergranular fracture mode close to the surface and a ductile mode at the center. The brittle intergranular fracture mode was associated with the slow subcritical crack growth, while the ductile mode was due to the final fast overload fracture. On the other hand, in the SLM-ed steel, both the subcritical crack growth and the final fast overload fracture were obtained by transgranular cleavage. This shows that under hydrogen the martensitic wrought steel is prone to brittle intergranular fracture in contrast to the ferritic SLM-ed steel which is subject to brittle transgranular cleavage. The same tendency is obtained under air when notched specimens are used. This propensity of the martensitic steel to fracture along prior austenite grain boundaries can be interpreted in terms of the easiest fracture path.
关键词： Cleavage,Subcritical crack growth,Martensitic stainless steels,Selective laser melting,Additive manufacturing,Hydrogen cracking,Hydrogen embrittlement,Intergranular
更新于2025-09-23 15:19:57
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Single-crystalline-like stainless steel 316L with different geometries fabricated by laser powder bed fusion
摘要： In this study, we explored the feasibility of fabricating single-crystalline or single-crystalline-like stainless steel 316L (SS316L) with different geometries (thin struts, cubes, walls and a simulated pump impeller) using laser powder bed fusion (LPBF). The LPBF-fabricated SS316L thin struts possessed a single-crystalline core featuring a ?110? ∥ building direction (BD) crystallographic texture. The cubes, walls and the pump impeller preserved this ?110? ∥ BD texture and also exhibited a well-defined single-crystalline-like {110}?001? Goss texture. Cellular sub-grain structures with their primary dendrite arm spacing (PDAS) values smaller than 1 μm were discovered in all the samples with their growth directions showing a 45° angular deviation from the BD. Nanoscale precipitates and dislocations were also found in the cellular sub-grain structures of the thin struts. The mechanical properties of different geometries (the thin struts, the walls, and the simulated pump impeller) were studied and compared. The anisotropic mechanical responses of the walls and the simulated pump impeller were correlated with their crystallographic textures.
关键词： Single crystal,Geometries,Crystallographic texture,Laser powder bed fusion,Mechanical properties,Stainless steel 316L
更新于2025-09-23 15:19:57
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An insight into microstructural heterogeneities formation between weld subregions of laser welded copper to stainless steel joints
摘要： The effect of laser beam welding (LBW) process on the microstructure?mechanical property relationship of a dissimilar weld between the copper (Cu) and stainless steel (SS) was investigated. Backscattered electron (BSE) based scanning electron microscopy (SEM) imaging was used to characterize the highly heterogeneous microstructural features across the LBW (Cu?SS) weld. The BSE analysis thoroughly evidenced the complex microstructures produced at dissimilar weld interfaces and fusion zone along with the compositional information. Widely different grain growths from coarse columnar grains to equiaxed ultrafine grains were also evident along the Cu?weld interface. A high-resolution electron backscattered diffraction (EBSD) analysis confirmed the existence of the grain refinement mechanism at the Cu?weld interface. Both tensile and impact properties of the dissimilar weld were found to be closely aligned with the property of Cu base metal. Microhardness gradients were spatially evident in the non-homogeneous material composition zones such as fusion zone and the Cu?weld interface regions. The heterogeneous nucleation spots across the weld sub-regions were clearly identified and interlinked with their microhardness measurements for a holistic understanding of structure?property relationships of the local weld sub-regions. The findings were effectively correlated to achieve an insight into the local microstructural gradients across the weld.
关键词： impact toughness,laser beam welding,stainless steel,microstructural characterization,copper,tensile property
更新于2025-09-23 15:19:57
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Microstructure and Corrosion Properties of Laser-Welded SAF 2507 Super Duplex Stainless Steel Joints
摘要： SAF 2507 super duplex stainless steel has been welded using laser beam (LB) welding and laser/gas metal arc hybrid (LGH) welding processes. The pitting and intergranular corrosion properties of the welding joints have been tested using electrochemical testing and microstructure observations. The volume fraction of the ferrite phase reaches 70% in the weld zone of the LB welding joint, while the volume fraction of the ferrite phase is 60% for the welding joint of LGH due to the introduction of Ni from welding wire. The pitting corrosion resistance of the welding joint for LB is better than that of LGH. The pitting corrosion is easily conceived in the heat-affected zone (HAZ) because of the formation of Cr2N in the HAZ during welding.
关键词： intergranular corrosion,pitting corrosion,super duplex stainless steel,laser-GMAW hybrid welding,laser beam welding
更新于2025-09-23 15:19:57