scholarly journals Study of Microstructure and Properties of 316L with Selective Laser Melting Based on Multivariate Interaction Influence

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Jianfeng Sun ◽  
Lu Shen ◽  
Weiqiang Wang ◽  
Zhu Liu ◽  
Huaming Chen ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Secondary Growth ◽  
Engineering Application ◽  
Regression Equations ◽  
Laser Melting ◽  
Performance Indexes ◽  
Study Results ◽  
Practical Engineering ◽  
Scan Speed ◽  
Grain Width

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.

Influence of Selective Laser Melting Process Parameters on Densification Behavior, Surface Quality and Hardness of 18Ni300 Steel

2020 ◽  
Vol 861 ◽  
pp. 77-82
Author(s):  
Gan Li ◽  
Cheng Guo ◽  
Wen Feng Guo ◽  
Hong Xing Lu ◽  
Lin Ju Wen ◽  
...  
Keyword(s):  
Energy Density ◽  
Relative Density ◽  
Maraging Steel ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Laser Power ◽  
Densification Behavior ◽  
Laser Melting ◽  
Scan Speed

This study investigated the effect of laser power (P), scan speed (v) and hatch space (h) on densification behavior, surface quality and hardness of 18Ni300 maraging steel fabricated by selective laser melting (SLM). The results indicated that the relative density of the SLMed samples has a shape increase from 73% to 97% with the laser energy density increasing from 0.5 to 2.2 J/mm2. The relative density ≥ 99% was achieved at the energy density in the range of 2.2~5.9 J/mm2. The optimum process parameters were found to be laser power of 150~200 W, scan speed of 600mm/s and hatch space of 0.105mm. In addition, it was found that the hardness increased initially with the increasing relative density up to relative density of 90% and then little relationship, but finally increase again significantly. This work provides reference for determining process parameters for SLMed maraging steel and the development of 3D printing of die steels.

Experimental Investigation of Selective Laser Melting of Lunar Regolith for In-Situ Applications

2013 ◽  
Author(s):  
Miranda Fateri ◽  
Andreas Gebhardt ◽  
Maziar Khosravi
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Lunar Regolith ◽  
Laser Melting ◽  
Manufacturing Method ◽  
3D Objects ◽  
Scan Speed ◽  
Manufacturing Methods ◽  
Object Layer

Selective Laser Melting (SLM) is a powder based Additive manufacturing (AM) technology which builds an object layer wise using a laser beam to melt the powder on an elevated platform. Thus far numerous studies have investigated lunar manufacturing methods and construction but little is known about applicability of SLM of lunar regolith. As most lunar construction proposals require transportation of essential materials from Earth, using an in-situ manufacturing method with indigenous material would be considerably more economical. Fabrication of parts with SLM using various metals and ceramics has already been presented. As such, the feasibility of using lunar regolith mixture to create functional parts with SLM process is investigated. Variation of process parameters such as laser power, scan speed, and scan strategies is investigated and multiple 3D objects are successfully created and presented.

Effect of processing parameters on forming defects during selective laser melting of AlSi10Mg powder

2020 ◽  
Vol 26 (5) ◽  
pp. 871-879 ◽  
Author(s):  
Haihua Wu ◽  
Junfeng Li ◽  
Zhengying Wei ◽  
Pei Wei
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Argon Pressure ◽  
Powder Layer ◽  
Laser Melting ◽  
Content Type ◽  
Scan Speed ◽  
Forming Defects

Purpose To fabricate a selective laser melting (SLM)-processed AlSi10Mg part with almost full density and free of any apparent pores, this study aims to investigate the effect of ambient argon pressure and laser scanning speed on the particles splash during the AlSi10Mg powder bed laser melting. Design/methodology/approach Based on the discrete element method (DEM), a 3D model of random distribution of powder particles was established, and the 3D free surface of SLM forming process was dynamically tracked by the volume of fluid, where a Gaussian laser beam acts as the energy source melting the powder bed. Through the numerical simulation and process experimental research, the effect of the applied laser power and scanning speed on the operating laser melting temperature was studied. Findings The process stability has a fundamental role in the porosity formation, which is process-dependent. The effect of the processing conditions on the process stability and the resultant forming defects were clarified. Research limitations/implications The results shows that the pores were the main defects present in the SLM-processed AlSi10Mg sample, which decreases the densification level of the sample. Practical implications The optimal processing parameters (argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm ) applied during laser melting can improve the quality of selective laser melting of AlSi10Mg, Social implications It can provide a technological support for 3D printing. Originality/value Based on the analysis of the pore and balling formation mechanisms, the optimal processing parameters have been obtained, which were argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm. Then, a near-fully dense sample free of any apparent pores on the cross-sectional microstructure was produced by SLM, wherein the relative density of the as-built samples is larger than 97.5%.

scholarly journals Optimisation of selective laser melting for a high temperature Ni-superalloy

2015 ◽  
Vol 21 (4) ◽  
pp. 423-432 ◽  
Author(s):  
Luke N. Carter ◽  
Khamis Essa ◽  
Moataz M Attallah
Keyword(s):  
High Temperature ◽  
Response Surface ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Laser Power ◽  
Surface Model ◽  
Good Prediction ◽  
Laser Melting ◽  
Content Type ◽  
Scan Speed

Purpose – The purpose of this paper is to optimise the selective laser melting (SLM) process parameters for CMSX486 to produce a “void free” (fully consolidated) material, whilst reducing the cracking density to a minimum providing the best possible fabricated material for further post-processing. SLM of high temperature nickel base superalloys has had limited success due to the susceptibly of the material to solidification and reheat cracking. Design/methodology/approach – Samples of CMSX486 were fabricated by SLM. Statistical design of experiments (DOE) using the response surface method was used to generate an experimental design and investigate the influence of the key process parameters (laser power, scan speed, scan spacing and island size). A stereological technique was used to quantify the internal defects within the material, providing two measured responses: cracking density and void per cent. Findings – The analysis of variance (ANOVA) was used to determine the most significant process parameters and showed that laser power, scan speed and the interaction between the two are significant parameters when considering the cracking density. Laser power, scan speed, scan spacing and the interaction between power and speed, and speed and spacing were the significant factors when considering void per cent. The optimum setting of the process parameters that lead to minimum cracking density and void per cent was obtained. It was shown that the nominal energy density can be used to identify a threshold for the elimination of large voids; however, it does not correlate well to the formation of cracks within the material. To validate the statistical approach, samples were produced using the predicted optimum parameters in an attempt to validate the response surface model. The model showed good prediction of the void per cent; however, the cracking results showed a greater deviation from the predicted value. Originality/value – This is the first ever study on SLM of CMSX486. The paper shows that provided that the process parameters are optimised, SLM has the potential to provide a low-cost route for the small batch production of high temperature aerospace components.

Direct Selective Laser Sintering of WC-Co Cemented Carbide by Premixing of Additives

2012 ◽  
Author(s):  
Hideki Kyogoku ◽  
Takeshi Uemori ◽  
Akihiko Ikuta ◽  
Kenichi Yoshikawa ◽  
Hitoshi Ohmori
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Smooth Surface ◽  
Laser Scanning ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Cemented Carbides ◽  
Sintering Process ◽  
Laser Melting ◽  
Scan Speed

In this study, the fabrication conditions of WC cemented carbides by direct selective laser melting were investigated. The effects of additives, such as Co, Cu-20%Sn and Cu powders, and laser scanning conditions on laser sintering process were examined to fabricate a sound laser-scanned body of WC cemented carbides. The optimum laser power, scan speed and scan pitch were found out by experiments. It was found that the continuously smooth single-scan track can be obtained at a lower laser power and a higher scan speed by the addition of 30% Cu powder. The smooth surface of the laser-scanned body could be fabricated at a laser power of 9 W, a scan speed of 20 mm/s and a scan pitch of 0.05 mm.

Build Orientation Effect on Geometric Performance of Curved-Surface 316L Stainless Steel Parts Fabricated by Selective Laser Melting

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Yue Zhou ◽  
Fuda Ning
Keyword(s):  
Stainless Steel ◽  
Selective Laser Melting ◽  
316L Stainless Steel ◽  
Curved Surface ◽  
Laser Melting ◽  
Metal Parts ◽  
Build Orientation ◽  
Practical Engineering ◽  
Actual Profile ◽  
Surface Metal

Abstract Selective laser melting (SLM) is a powder bed fusion additive manufacturing technology that allows the production of high-performance metal parts with geometrically complex shapes, such as curved surface, can be used in practical engineering applications. In recent years, systematic attempts have been made to uncover the material-process-microstructure-property linkage in SLM-fabricated planar-surface metal parts; however, little is known on the performance and quality of SLM-fabricated metal parts with curved surfaces. In this paper, we studied the effects of build orientation on the geometric performance of SLM-built 316L stainless steel (SS) samples with a sinusoidal curved surface. The results indicated that the average values of profile roughness Ra and surface texture attributes Sa, Sk, and Vmc decreased with the increase in build orientation. Moreover, the locations at curvatures C2 and C4 exhibited the best surface finish at the build orientation of 75 deg and 90 deg. In addition, the least square method was used to fit the actual profile of the curved surface of as-built samples fabricated at each build orientation, and it was found the actual profile demonstrated the best consistency with the designed one at 90 deg build orientation. In this paper, the process–curvature–geometric performance relationship of SLM-built metal parts with curved surface was uncovered. In addition, this paper provides keen insights into assessing the geometric performance of SLM-built curved-surface metal parts and establishes a roadmap toward SLM-fabrication of metal parts with complex geometries for practical engineering applications.

Atomic-level crystallization in selective laser melting fabricated Zr-based metallic glasses

2019 ◽  
Vol 21 (23) ◽  
pp. 12406-12413 ◽  
Author(s):  
Yue Zhang ◽  
Haishun Liu ◽  
Jinyong Mo ◽  
Mingzi Wang ◽  
Zhe Chen ◽  
...  
Keyword(s):  
Temperature Variation ◽  
Selective Laser Melting ◽  
Metallic Glasses ◽  
Atomic Level ◽  
Laser Melting ◽  
Average Temperature ◽  
Scan Speed ◽  
Variation Rate ◽  
Temperature Variation Rate

Scan speed impacts greatly on average temperature variation rate and thus atomic-level changes in clusters and crystallization.

Selective Laser Melting of Nanocomposite Ti-6Al-4V and TiC Powder

2019 ◽  
Vol 822 ◽  
pp. 575-579 ◽  
Author(s):  
Evgenii Borisov ◽  
Dmitriy V. Masaylo ◽  
Vera Popovich
Keyword(s):  
Composite Material ◽  
Selective Laser Melting ◽  
Mechanical Characteristics ◽  
Melting Process ◽  
Nanosized Powder ◽  
Laser Melting ◽  
Selective Laser Melting Process ◽  
Powder Composition ◽  
Study Results ◽  
Electron Microscopes

The paper presents the study results of the selective laser melting process of the Ti-6Al-4V alloy and nanosized powder TiC composition. The results of the particles morphology study of resulting powder composition after blending are presented. The microstructure and mechanical characteristics of the obtained composite material were studied. Study of microstructures using optical and electron microscopes were conducted.

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