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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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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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Collaborative Optimization of Density and Surface Roughness of 316L Stainless Steel in Selective Laser Melting
摘要： Although the concept of additive manufacturing has been proposed for several decades, momentum in the area of selective laser melting (SLM) is ?nally starting to build. In SLM, density and surface roughness, as the important quality indexes of SLMed parts, are dependent on the processing parameters. However, there are few studies on their collaborative optimization during SLM to obtain high relative density and low surface roughness simultaneously in the literature. In this work, the response surface method was adopted to study the in?uences of di?erent processing parameters (laser power, scanning speed and hatch space) on density and surface roughness of 316L stainless steel parts fabricated by SLM. A statistical relationship model between processing parameters and manufacturing quality is established. A multi-objective collaborative optimization strategy considering both density and surface roughness is proposed. The experimental results show that the main e?ects of processing parameters on the density and surface roughness are similar. We observed that the laser power and scanning speed signi?cantly a?ected the above objective quality, but the in?uence of the hatch spacing was comparatively low. Based on the above optimization, 316L stainless steel parts with excellent surface roughness and relative density can be obtained by SLM with optimized processing parameters.
关键词： 316L stainless steel,multi-objective optimization,relative density,selective laser melting,surface roughness
更新于2025-09-19 17:13:59
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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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Fiber laser induced self-organizing structures of 316L stainless steel surface
摘要： When the micro-nano groove structure is processed on the surface of 316L stainless steel by a fiber laser, a self-organizing structure with regular distribution appears. After optimizing the processing parameters, the self-organizing structure with excellent quality can be formed in the groove. In order to further research the properties of the self-organizing structure, the large-area self-organizing structures with different spacings are processed. It is found by the characterization that when the spacing is 50 um, the contact angle of the large-area self-organizing structure is increased by 43.1% with respect to the smooth surface, and its wetting property changes from hydrophilicity to hydrophobicity. The component and the phase composition of the self-organizing structure were found to be consistent with the composition of the original material, and it is preliminarily concluded that the self-organizing structure is formed by the splashing flow of molten liquid in the oxidizing molten pool.
关键词： self-organizing structure,fiber laser,contact angle,component,316L stainless steel
更新于2025-09-12 10:27:22
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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