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Analysis of Melt-Pool Behaviors during Selective Laser Melting of AISI 304 Stainless-Steel Composites
摘要： The melt-pool behaviors during selective laser melting (SLM) of Al2O3-reinforced and a eutectic mixture of Al2O3-ZrO2-reinforced AISI 304 stainless-steel composites were numerically analyzed and experimentally validated. The thermal analysis results show that the geometry of the melt pool is significantly dependent on reinforcing particles, owing to the variations in the melting point and the thermal conductivity of the powder mixture. With the use of a eutectic mixture of Al2O3-ZrO2 instead of an Al2O3 reinforcing particle, the maximum temperature of the melt pool was increased. Meanwhile, a negligible corresponding relationship was observed between the cooling rate of both reinforcements. Therefore, it was identified that the liquid lifetime of the melt pool has the effect on the melting behavior, rather than the cooling rate, and the liquid lifetime increases with the eutectic ratio of Al2O3-ZrO2 reinforcement. The temperature gradient at the top surface reduces with the use of an Al2O3-ZrO2 reinforcement particle due to the wider melt pool. Inversely, the temperature gradient in the thickness direction increases with the use of an Al2O3-ZrO2 reinforcement particle. The results of melt-pool behaviors will provide a deep understanding of the effect of reinforcing particles on the dimensional accuracies and properties of fabricated AISI 304 stainless-steel composites.
关键词： FEM,Al2O3,Al2O3-ZrO2,304,composite,SLM,additive manufacturing,selective laser melting,stainless
更新于2025-09-16 10:30:52
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Optimization of CO 2 Laser Cutting of Stainless Steel Sheet for Curved Profile
摘要： Laser cutting is one of the most widely used thermal energy based non-contact type advance machining process. In recent years, considerable experimental investigations have been carried out aiming at improving laser cutting process performance. In this work CO2 laser cutting parameters on stainless steel 304 width 2.5 mm thickness were studied. The cut quality achieved minimum kerf width to cut stainless steel sheet depends on appropriate selection process parameters was investigated. The parameters consider to include laser output power, cutting speed, gas pressure. The effect of cutting parameter on the cut quality was further investigated by monitoring top kerf width, and bottom kerf width using box –behnken designing the response surface methodology. And finally optimized best CO2 laser cutting parameters are selected by using genetic algorithm approach.
关键词： Kerf width,Stainless steel 304,CO2 Laser cutting,GA,RSM
更新于2025-09-16 10:30:52
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Effects of Laser Beam Parameters on Bendability and Microstructure of Stainless Steel in Three-Dimensional Laser Forming
摘要： In this study, the e?ects of beam diameter and hatch spacing between the scanning paths on the bendability and microstructural behavior of an AISI 316 stainless-steel sheet in three-dimensional laser forming were investigated. The strain on the heating lines and that between the scanning tracks were numerically investigated to elucidate the e?ects of process parameters. The strain on heating lines and that between scanning tracks were numerically investigated. The increase in hatch spacing caused a larger amount of counter bending to be retained in the una?ected areas between the tracks through a process dominated by a temperature gradient mechanism (TGM), and also caused a lower deformation. The formation of small equiaxed dendrite grains instead of coarse and inhomogeneous austenite grains occurred during the process at a larger beam diameter and smaller hatch spacing, which increased the bendability of the material, owing to the decrease in anisotropy in the microstructure. Moreover, the increase in the grain size of the reheated overlap region of the deformed sample led to a higher bendability. Under these conditions, the microhardness was also increased owing to the grain boundary strengthening e?ect.
关键词： laser forming,track overlap,stainless steel,laser bending,bendability,hatch spacing
更新于2025-09-16 10:30:52
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Influences of Horizontal and Vertical Build Orientations and Post-Fabrication Processes on the Fatigue Behavior of Stainless Steel 316L Produced by Selective Laser Melting
摘要： In this paper, the influences of build orientation and post-fabrication processes, including stress-relief, machining, and shot-peening, on the fatigue behavior of stainless steel (SS) 316L manufactured using selective laser melting (SLM) are studied. It was found that horizontally-built (XY) and machined (M) test pieces, which had not been previously studied in the literature, in both stress-relieved (SR) or non-stress-relieved (NSR) conditions show superior fatigue behavior compared to vertically-built (ZX) and conventionally-manufactured SS 316L. The XY, M, and SR (XY-M-SR) test pieces displayed fatigue behavior similar to the XY-M-NSR test pieces, implying that SR does not have a considerable effect on the fatigue behavior of XY and M test pieces. ZX-M-SR test pieces, due to their considerably lower ductility, exhibited significantly larger scatter and a lower fatigue strength compared to ZX-M-NSR samples. Shot-peening (SP) displayed a positive effect on improving the fatigue behavior of the ZX-NSR test pieces due to a compressive stress of 58 MPa induced on the surface of the test pieces. Fractography of the tensile and fatigue test pieces revealed a deeper understanding of the relationships between the process parameters, microstructure, and mechanical properties for SS 316L produced by laser systems. For example, fish-eye fracture pattern or spherical stair features were not previously observed or explained for cyclically-loaded SLM-printed parts in the literature. This study provides comprehensive insight into the anisotropy of the static and fatigue properties of SLM-printed parts, as well as the pre- and post-fabrication parameters that can be employed to improve the fatigue behavior of steel alloys manufactured using laser systems.
关键词： fracture,fatigue,selective laser melting,defect,stainless steel 316L
更新于2025-09-16 10:30:52
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Study on Effect of Post Processing on Direct Metal LASER Sintered 420 Stainless steel Infiltrated with Bronze
摘要： Additive manufacturing (AM) of metals is increasing its potential applications in the areas of aerospace, automobile, defense and medical with the processing capability from light to heavy metals, but still low density of the finished products which causes discrimination to functional properties and thus reducing AM process real time efficiency. Current research focus on improving the functional properties of 420 stainless steel specimens which are fabricated by Direct Metal LASER Sintering (DMLS) process and infiltrated with bronze for improving the density. Also post processing i.e. annealing, deep cryogenic treatment and tempering was performed. By studying the mechanical properties like tensile strength, hardness, wear of material of specimens in as fabricated and post processed condition it was observed that post processing treatment will favours in enhancing the functional properties. Also results are compared with SEM and optical microscopy images in order to determine microstructural changes.
关键词： deep cryogenic treatment,Infiltration with bronze,Additive manufacturing,420 stainless steel,annealing,tempering
更新于2025-09-16 10:30:52
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Conductive and convective heat transfer during welding of AISI316L stainless steel using pulsed Nd: YAG laser
摘要： Conductive and convective heat transfers during an autogenous butt joint welding of AISI 316L stainless steel sheets using pulsed Nd: YAG laser have investigated. An FEA based three-dimensional model was developed to receive the transient thermal responses across the weld pool and the predicted results are compared with experimental observations. The heat transfer in the keyhole region, melt ?ow directions around the keyhole and heat affected zone are computed for consecutive pulse irradiation during laser welding and the same was investigated on far with experiment. The temperature distribution have predicted in terms of inward heat ?ux and Paclet number to investigate the heat and mass transportation in the weld pool. These results have taken for discussion and found that has a close association with experimental results.
关键词： Peclet Number,Pulsed laser welding,Melt ?ow,316L Stainless steel,Moving heat source,Heat transfer
更新于2025-09-16 10:30:52
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Austenitic Stainless Steel Powders with Increased Nitrogen Content for Laser Additive Manufacturing
摘要： Nitrogen is used as an alloying element, substituting the expensive and allergenic element nickel, in austenitic stainless steels to improve their mechanical properties and corrosion resistance. The development of austenitic stainless steel powders with increased nitrogen content for laser additive manufacturing has recently received great interest. To increase nitrogen content in the austenitic steel powders (for example AISI 316L), two measures are taken in this study: (1) melting the steel under a nitrogen atmosphere, and (2) adding manganese to increase the solubility of nitrogen in the steel. The steel melt is then atomized by means of gas atomization (with either nitrogen or argon). The resulting powders are examined and characterized with regard to nitrogen content, particle size distribution, particle shape, microstructure, and ?owability. It shows that about 0.2–0.3 mass % nitrogen can be added to the austenitic stainless steel 316L by adding manganese and melting the steel under nitrogen atmosphere. The particles are spherical in shape and very few satellite particles are observed. The steel powders show good ?owability and packing density, therefore they can be successfully processed by means of laser powder bed fusion (L-PBF).
关键词： nitrogen alloying,powder production,austenitic stainless steel,gas atomization,laser additive manufacturing
更新于2025-09-16 10:30:52
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Transferability of Process Parameters in Laser Powder Bed Fusion Processes for an Energy and Cost Efficient Manufacturing
摘要： In the past decade, the sales of metal additive manufacturing systems have increased intensely. In particular, PBF-LB/M systems (powder bed fusion of metals using a laser-based system) represent a technology of great industrial interest, in which metallic powders are molten and solidified layer upon layer by a focused laser beam. This leads to a simultaneous increase in demand for metallic powder materials. Due to adjusted process parameters of PBF-LB/M systems, the powder is usually procured by the system’s manufacturer. The requirement and freedom to process different feedstocks in a reproducible quality and the economic and ecological factors involved are reasons to have a closer look at the differences between the quality of the provided metallic powders. Besides, different feedstock materials require different energy inputs, allowing a sustainable process control to be established. In this work, powder quality of stainless steel 1.4404 and the effects during the processing of metallic powders that are nominally the same were analyzed and the influence on the build process followed by the final part quality was investigated. Thus, a correlation between morphology, particle size distribution, absorptivity, flowability, and densification depending on process parameters was demonstrated. Optimized exposure parameters to ensure a more sustainable and energy and cost-efficient manufacturing process were determined.
关键词： powder characterization,stainless steel (1.4404; 316L),energy and cost-efficient manufacturing,PBF-LB/M,sustainable process parameters,additive manufacturing
更新于2025-09-16 10:30:52
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Effects of laser additive manufacturing on microstructure and crystallographic texture of austenitic and martensitic stainless steels
摘要： Powder-fed laser additive manufacturing (LAM) based on directed energy deposition (DED) technology is used to produce S316-L austenitic, and S410-L martensitic stainless steel structures by 3D-printing through a layer-upon-layer fashion. The microstructural features and crystallographic textural components are studied via electron backscattering diffraction (EBSD) analysis, hardness indentation and tensile testing. The results are compared with commercial rolled sheets of austenitic and martensitic stainless steels. A well-developed <100> direction solidification texture (with a J-index of ~11.5) is observed for the austenitic structure produced by the LAM process, compared to a J-index of ~2.0 for the commercial austenitic rolled sheet. Such a texture in the LAM process is caused by equiaxed grain formation in the middle of each layer followed by columnar growth during layer-upon-layer deposition. A quite strong preferred orientation (J-index of 17.5) is noticed for martensitic steel developed by LAM. Large laths of martensite exhibit a dominant textural component of <011>//{111} in the α-phase, which is mainly controlled by transformation during layer-by-layer deposition. On the other hand, the martensitic commercial sheet consists of equiaxed grains without any preferred orientation or completely random orientations. In the case of the austenitic steel, mechanical properties such as tensile strength, hardness and ductility were severely deteriorated during the LAM deposition. A ductility loss of about 50% is recorded compared to the commercially rolled sheets that is attributed to the cast/solidified structure. However, LAM manufacturing of martensitic stainless steel structures leads to a considerably enhanced mechanical strength (more than double) at the expense of reduced ductility, because of martensitic phase transformations under higher cooling rates.
关键词： Directed energy deposition (DED),Laser additive manufacturing (LAM),Crystallographic texture,S316-L austenitic stainless steel,S410-L martensitic stainless steel
更新于2025-09-12 10:27:22
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Reducing the pitting susceptibility of AISI 304 stainless steel using a hybrid treatment of high-power diode laser and large pulsed electron beam irradiation
摘要： Large pulsed electron beam (LPEB) irradiation has been widely used for surface modification of metals, alloys, polymers, and composites due to its unique interaction mechanisms with materials. The rapid melting and resolidification processes during LPEB irradiation induce phase transformation at the resolidified layer, which enables a simultaneous improvement in mechanical characteristics and chemical stability of metals. However, the generation of craters during LPEB irradiation adversely affects surface quality. It is imperative to minimize crater formation following LPEB irradiation to mitigate pitting corrosion on the surface of stainless steel (SS). In this study, a hybrid surface modification approach using a high-power diode laser (HPDL) and LPEB is proposed to reduce the crater generation during LPEB irradiation. The size and density of craters generated during LPEB irradiation were effectively reduced following the HPDL-LPEB irradiation hybrid surface treatment. The decrease in extent of crater formation and phase transformation has enabled an improvement in corrosion resistance. The ability of the resolidified layer formed after the hybrid HPDL-LPEB irradiation to form a stable passive film shifts the pitting potential from less than 0 mV/SCE (for untreated 304 SS) to more than +800 mV/SCE, which reduced the depth of corroded pits by 75%. The hybrid HPDL-LPEB irradiation decreased non-metallic inclusions, extent of crater formation and the surface roughness, and improved the pitting corrosion and general corrosion resistance.
关键词： High power diode laser,Pitting corrosion,Electron beam,Microstructure,Corrosion resistance,Stainless steels
更新于2025-09-12 10:27:22