Selective Laser Melting of 18NI-300 Maraging Steel

In the present study, 18% Ni 300 maraging steel powder was processed using a selective laser melting (SLM) technique to study porosity variations, microstructure, and hardness using various process conditions, while maintaining a constant level of energy density. Nowadays, there is wide range of utilization of metal technologies and its products can obtain high relative density. A dilatometry study revealed that, through heating cycles, two solid-state effects took place, i.e., precipitation of intermetallic compounds and the reversion of martensite to austenite. During the cooling process, one reaction took place (i.e., martensitic transformation), which was confirmed by microstructure observation. The improvements in the Rockwell hardness of the analyzed material from 42 ± 2 to 52 ± 0.5 HRC was improved as a result of aging treatment at 480 °C for 5 h. The results revealed that the relative density increased using laser speed (340 mm/s), layer thickness (30 µm), and hatch distance (120 µm). Relative density was found approximately 99.3%. Knowledge about the influence of individual parameters in the SLM process on porosity will enable potential manufacturers to produce high quality components with desired properties.

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Fabrication of Mesh Patterns Using a Selective Laser-Melting Process

Applied Sciences ◽

10.3390/app9091922 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1922 ◽

Cited By ~ 3

Author(s):

Tae Woo Hwang ◽

Young Yun Woo ◽

Sang Wook Han ◽

Young Hoon Moon

Keyword(s):

Selective Laser Melting ◽

Laser Scanning ◽

Dimensional Accuracy ◽

Base Plate ◽

Steel Powder ◽

Melting Process ◽

304 Stainless Steel ◽

Process Conditions ◽

Laser Melting ◽

Metal Mesh

The selective laser-melting (SLM) process can be applied to the additive building of complex metal parts using melting metal powder with laser scanning. A metal mesh is a common type of metal screen consisting of parallel rows and intersecting columns. It is widely used in the agricultural, industrial, transportation, and machine protection sectors. This study investigated the fabrication of parts containing a mesh pattern from the SLM of AISI 304 stainless steel powder. The formation of a mesh pattern has a strong potential to increase the functionality and cost-effectiveness of the SLM process. To fabricate a single-layered thin mesh pattern, laser layering has been conducted on a copper base plate. The high thermal conductivity of copper allows heat to pass through it quickly, and prevents the adhesion of a thin laser-melted layer. The effects of the process conditions such as the laser scan speed and scanning path on the size and dimensional accuracy of the fabricated mesh patterns were characterized. As the analysis results indicate, a part with a mesh pattern was successfully obtained, and the application of the proposed method was shown to be feasible with a high degree of reliability.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.861.77 ◽

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.

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Selective Laser Melting of High Relative Density and High Strength Parts Made of Minor Surface Oxidation Treated Pure Copper Powder

Metals ◽

10.3390/met11121883 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1883

Author(s):

Peng Yang ◽

Xingye Guo ◽

Dingyong He ◽

Zhen Tan ◽

Wei Shao ◽

...

Keyword(s):

Relative Density ◽

Selective Laser Melting ◽

Pure Copper ◽

Surface Oxidation ◽

High Strength ◽

Microstructural Characterization ◽

Laser Melting ◽

Oxidation Treatment ◽

High Relative Density ◽

Pure Cu

Pure Copper (Cu) is very difficult to prepare using selective laser melting (SLM) technology. This work successfully prepared the pure Cu with high relative density and high strength by the SLM technology using a surface oxidation treatment. The gas-atomized pure Cu powder was used as the feedstock in this work. Before the SLM process, the pure Cu powder was initially handled using the surface oxidation treatment to coat the powder with an extremely thin layer of Cu2O. The SLMed highly dense specimens contain α-Cu and nano-Cu2O phases. A relationship between the processing parameters (laser power (LP), scanning speed (SS), and hatch space (HS)) and density of Cu alloy in SLM was also investigated. The microstructure of SLMed Cu consists of fine grains with grain sizes ranging from 0.5 to ~30 μm. Tensile testing and detailed microstructural characterization were performed on specimens in the as-SLMed and pure copper state specimens. The mechanical property experiments showed that the specimens prepared by SLM technology containing nano-oxide phases had higher yield strength and tensile strength than that of other SLM-built pure copper. However, the elongation was remarkably decreased compared to other SLM-built pure copper, due to the fine grains and the nano-oxides.

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Dependence of Microstructure, Relative Density and Hardness of 18Ni-300 Maraging Steel Fabricated by Selective Laser Melting on the Energy Density

Lecture Notes in Mechanical Engineering - Advances in Materials Processing ◽

10.1007/978-981-13-0107-0_22 ◽

2018 ◽

pp. 229-241

Author(s):

Jie Tian ◽

Zhenghua Huang ◽

Wenjun Qi ◽

Yajiang Li ◽

Jianye Liu ◽

...

Keyword(s):

Energy Density ◽

Relative Density ◽

Maraging Steel ◽

Selective Laser Melting ◽

Laser Melting

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Selective Laser Melting of Maraging Steel Using Synchronized Three-Spot Scanning Strategies

Materials ◽

10.3390/ma14081905 ◽

2021 ◽

Vol 14 (8) ◽

pp. 1905

Author(s):

Chung-Wei Cheng ◽

Wei-You Jhang Jian ◽

Bhargav Prasad Reddy Makala

Keyword(s):

Relative Density ◽

Maraging Steel ◽

Selective Laser Melting ◽

Surface Hardness ◽

Industrial Applications ◽

Laser Melting ◽

Manufacturing Method ◽

Part Quality ◽

Spot Scanning ◽

Scanning Strategies

The selective laser melting (SLM) process, a kind of metal additive manufacturing method, can produce parts with complex geometries that cannot be easily manufactured using material removal processes. With increasing industrial applications, there are still issues such as part quality and productivity that need to be resolved. In this study, maraging steel parts fabricated by synchronized three-spot scanning strategies, i.e., lateral spatial (LS) and spatial inline (SiL), are firstly presented. The LS and SiL represent the three-spot offset direction is perpendicular and parallel to the scanning direction, respectively. A laboratory SLM machine equipped with a fiber laser and three-spot module is used to fabricate the maraging steel parts with two scanning strategies, i.e., LS and SiL. The influence of these scanning strategies on the surface roughness, relative density, hardness, molten pool shapes, and microstructures are investigated. The relative density (~99.02%) and surface hardness (~34.0 HRC) are experimentally found to be higher than the SiL by the LS scanning strategy.

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Heat Treatment Behavior of the 18Ni300 Maraging Steel Additively Manufactured by Selective Laser Melting

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.2160 ◽

2018 ◽

Vol 941 ◽

pp. 2160-2166 ◽

Cited By ~ 2

Author(s):

W.F. Guo ◽

C. Guo ◽

Qiang Zhu

Keyword(s):

Heat Treatment ◽

Maraging Steel ◽

Selective Laser Melting ◽

Aging Treatment ◽

Casting Process ◽

Age Hardening ◽

Laser Melting ◽

Reverted Austenite ◽

And Performance ◽

Evolution Of Microstructure

The steel 18Ni300 is widely used for tooling of injection moulding and die casting industries. Additive manufacturing (AM) technology is applicable to manufacture dies with “ideal” design without construction of manufacturing reality. Selective laser melting (SLM) processed materials have finer microstructure due to steeper temperature gradient and more rapid cooling conditions than conventional casting process during solidification. This difference may make different heat treatment behavior in obtaining optimal properties of the 18Ni300 maraging steel manufactured by SLM. Heat treatment is one of the most processes to improve microstructure, mechanical properties and performance of tooling dies. This work studies evolution of microstructure and properties during heat treatment, by X-ray diffraction, optical and scanning electron microscopy (SEM). The results show that the SLMed materials with only aging treatment have comparable strengths and hardness to those of conventionally cast materials with both solution and aging treatment. For the SLMed materials, with increase of aging time and/or temperature, the formed reverted austenite (γ-Fe) fraction increases, while aging precipitation hardening decreases. This is more apparent at aging temperatures of higher than 540°C. The combined effects of softening by formation of reverted austenite (γ-Fe) and age hardening induced by precipitation are discussed.

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The Effects of Selective Laser Melting Process Parameters on Relative Density of the AlSi10Mg Parts and Suitable Procedures of the Archimedes Method

Applied Sciences ◽

10.3390/app9030583 ◽

2019 ◽

Vol 9 (3) ◽

pp. 583 ◽

Cited By ~ 12

Author(s):

Shigang Bai ◽

Nataliya Perevoshchikova ◽

Yu Sha ◽

Xinhua Wu

Keyword(s):

Image Analysis ◽

Relative Density ◽

Selective Laser Melting ◽

Laser Power ◽

Regression Models ◽

Processing Parameters ◽

Response Surfaces ◽

Laser Melting ◽

High Relative Density ◽

Scan Speed

In view of the importance of accurately measuring the relative density of a selective laser melted (SLMed) part for optimizing the selective laser melting (SLM) processing parameters, suitable procedures of the Archimedes method considering the surface-connected cavities were proposed by comparing the results using the Archimedes method with image analysis. The effects of the SLM processing parameters on the relative density of AlSi10Mg were investigated using the proposed procedures of the Archimedes methods and image analysis. Fourteen SLMed samples were produced by different SLM processing parameters according to Doehlert Matrix. The regression models correlating relative density and three SLM processing parameters (laser power, scan speed, and hatching distance) were built and the optimum parameter combination to get a high relative density was obtained. By plotting the response surfaces and contours of the regression models, it was found that the relative densities are both higher at the combination of the higher scan speed, higher power, and lower hatching distance and at the combination of a lower scan speed, a moderate laser power, and a optional hatching distance. It was also found that the parameter of hatching distance is the crucial parameter to get a high relative density and to get high mechanical property.

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