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Influence of Processing Parameters on the Microhardness Property of Laser Cladded Titanium Powder
摘要： Laser cladding techniques of additive manufacturing has been globally embraced in the most efficient means of maintenance of steel rail. Nano-composite of titanium has been used as covering layer. The processing parameters of the laser power was varied between 1.0 kW and 2.0 kW while the scanning speed, powder and gas flow rate were kept at constant. Design expert 11 software environment was used to analyze the results derived with a full factorial experiment design guide. The microhardness profiling was performed at a load of 500 g and at a dwelling time of 15 s with the microhardness indenter 20 (cid:2)(cid:3)(cid:4) (cid:5)(cid:6)stance was maintained between indentations. An almost uniform weight of Titanium powder was cladded at different variation of processing parameters. A predictive microhardness equation was generated and termss runs intercept of an orthogonal shape. The model terms were found to be significant with logical relationships. It was found that the microhardness increases as the laser power increased.
关键词： microhardness,factorial experiment,steel rail,laser cladding,nano-composite
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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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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The International Round Robin Test of Magnetostriction Measurement of Grain-oriented Electrical Steel by Means of a Single Sheet Tester and an Optical Sensor
摘要： This paper reports the results of the round robin test (hereafter RRT) of magnetostriction measurement using the test apparatus following IEC 60404-17 from April 2019 to August 2019. The main purpose of the RRT is to identify factors affecting the magnetostriction measurement, and then to estimate the reproducibility of the measurements. Nine anonymous laboratories, whose test apparatuses are a little different from the draft standard, participated in the RRT. In the progress of the RRT, we identified factors affecting the magnetostriction measurement. Finally, the reproducibility of the measurements was estimated. Doshisha Univ. acts as the reference laboratory.
关键词： Single Sheet Tester,Optical Sensor,Magnetostriction,Grain-oriented Electrical Steel,Round Robin Test
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
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Effects of Low-Temperature Tempering on Microstructure and Properties of the Laser-Cladded AISI 420 Martensitic Stainless Steel Coating
摘要： Post-treatment is crucial to improve the comprehensive performance of laser-cladded martensitic stainless steel coatings. In this work, a low-temperature tempering treatment (210 ?C), for the ?rst time, was performed on the laser-cladded AISI 420 martensitic stainless steel coating. The microstructure and properties of the pre- and post-tempering specimens were carefully investigated by XRD, SEM, TEM, a micro-hardness tester, a universal material testing machine and an electrochemical workstation. The results show that the as-cladded AISI 420 stainless steel coating mainly consisted of martensite, austenite, Fe3C and M23C6 carbides. The phase constituent of the coating remained the same, however, the martensite decomposed into ?ner tempered martensite with the precipitation of numerous nano-sized Fe3C carbides and reverted austenite in the as-tempered specimen. Moreover, a slight reduction was found in the micro-hardness and tensile strength, while a signi?cant increase in elongation was achieved after tempering. The fractography showed a transition from brittle fracture to ductile fracture accordingly. The as-tempered coating exhibited a striking combination of mechanical properties and corrosion resistance. This work can provide a potential strategy to enhance the overall properties of the laser-deposited Fe-based coating for industrial applications.
关键词： microstructure,laser cladding,low-temperature tempering,properties,stainless steel coating
更新于2025-09-19 17:15:36
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Dependance of Poly(acrylic acid) Interfacial Adhesion on the Nanostructure of Electrodeposited ZnO Films
摘要： Understanding the impact of the intricate morphology and surface chemistry of ZnO nanorod arrays on their interactions with polyelectrolyte polymers is crucial for the development of nascent ZnO-based adhesion-promoting materials. AFM based Single Molecule Force Spectroscopy (SMFS) was applied for the analysis of the adsorption of poly(acrylic acid) (PAA) on zinc oxide (ZnO) film covered stainless steel substrates in aqueous electrolytes at pH 7. Based on the electrodeposition process, the morphology of zinc oxide films could be varied ranging from platelet-like crystals to nanorods. This approach allowed for the morphology dependent analysis of macromolecular adsorption processes on complex ZnO nanostructures which have diverse applications in the field of adhesion-promoting thin films. The surface chemical composition, as determined by X-ray photoelectron spectroscopy, could be correlated to the AFM-based desorption studies. Only equilibrium desorption events (plateaus), centered at 42 pN, were observed on mirror polished, preconditioned stainless steel. However, for platelet-like ZnO films, the poly(acrylic acid) desorption showed a mixture of rupture events (mean rupture forces of about 350 pN) and equilibrium desorption, while ZnO nanorod structures showed solely rupture events with mean rupture forces of about 1300 pN. These results indicate that simultaneous multiple ruptures of carboxylate-zinc bonds occur due to the macromolecular coordination of poly(acrylic acid) to the ZnO nanorods. The analysis of the interfacial adhesion processes is further supported by the dwell time dependence of desorption processes.
关键词： poly(acrylic acid),Single Molecule Force Spectroscopy (SMFS),worm like chain (WLC) model,stainless steel,zinc oxide (ZnO),electrochemical deposition,molecular adhesion,adsorption free energy
更新于2025-09-19 17:15:36
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Study of expanded austenite formed in plasma nitrided AISI 316L samples, using synchrotron radiation diffraction
摘要： AISI 316L stainless steel samples nitrided at different conditions of temperature and time, showing different properties, such as nitrogen concentration (CN) and nitrided layer thickness, were studied. Expanded austenite (gN) diffraction peaks up to the (222) reflection were observed using suitable wavelength synchrotron radiation. XRD patterns were fitted by Le Bail method, using a special triclinic crystal structure (with a lattice distortion η) for gN, whose peaks were decomposed in a few subpeaks, to consider CN gradient across the nitrided layer. Our results indicate that regarding gN magnetic behavior, which was observed for the samples nitrided at 450 °C, it seems to be correlated not only to high CN (≥31at.%), but also to higher η (≥2.4°), which reaches up to 5.6°. This distortion η decreases when CN increases, consequently, with its minimum close to the surface. On the other hand, for paramagnetic samples (350 °C), η increases up to 1.4° when CN increases up to 30 at.%.
关键词： magnetic character,layer depth,AISI 316L stainless steel,expanded austenite,synchrotron diffraction,plasma nitriding
更新于2025-09-19 17:15:36
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Analytical model for estimating bending angle in laser bending of 304 stainless steel/Q235 carbon steel laminated plate
摘要： Compared with the single-component metal plate, the stainless steel-carbon steel laminated plate (SCLP) combines the stainless steel layer and the carbon steel layer with a special preparation technique. In order to estimate the bending angle of laminated plates accurately, it is of great significance to establish an analytical model. Based on the temperature gradient mechanism, the temperature distribution equation of the SCLP is established by the piecewise function. Then, the depth of the plastic zone is calculated by the recrystallization temperature according to the temperature distribution along the thickness direction of the SCLP. Moreover, by fitting the yield strength curves of stainless steel and carbon steel, the average compressive stress of the plastic zone is calculated through the integral method. By optimizing the calculation of the plastic depth and the average compressive stress in the plastic zone, the analytical model is established based on mechanical equilibrium equations. The experimental verification shows that the average error of bending angle using the proposed model is 9.95%, while Liu’s model is 38.02%. The proposed model provides a calculation method for estimating the bending angle, which contributes to improving the accuracy of the analytical model in laser bending of SCLP.
关键词： stainless steel-carbon steel laminated plate,analytical model,bending angle,laser bending,depth of plastic zone
更新于2025-09-19 17:13:59