Optimization of selective laser melting parameters and influence of post heat treatment on microstructure and mechanical properties of maraging steel

Mutua, James; Nakata, Satoshi; Onda, Tetsuhiko; Chen, Zhongchun

doi:10.1016/j.matdes.2017.11.042

Cited by 240 publications

(157 citation statements)

References 20 publications

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“…In the laser powder fusion processes, the cellular or cellular-dendritic mode was not uncommon. This type of microstructure has been observed for different engineering alloys like austenitic steels, aluminum alloys Co-Cr, and nickel base alloys [5][6][7][10][11][12][13][14][15][16][17][18][19][20][21][22] manufactured by laser or electron powder bed fusion methods. At the high solidification rates observed in the PBF processes, a solute-rich boundary layer is built up in front of the solid-liquid interface due to the limited solute atom diffusion in the liquid phase, thus approaching the conditions for constitutional supercooling [27].…”

Section: Influence Of Solidification Conditions On Microstructure Andmentioning

confidence: 95%

Microstructure, Solidification Texture, and Thermal Stability of 316 L Stainless Steel Manufactured by Laser Powder Bed Fusion

Krakhmalev

Fredriksson

Svensson

et al. 2018

Metals

140

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This article overviews the scientific results of the microstructural features observed in 316 L stainless steel manufactured by the laser powder bed fusion (LPBF) method obtained by the authors, and discusses the results with respect to the recently published literature. Microscopic features of the LPBF microstructure, i.e., epitaxial nucleation, cellular structure, microsegregation, porosity, competitive colony growth, and solidification texture, were experimentally studied by scanning and transmission electron microscopy, diffraction methods, and atom probe tomography. The influence of laser power and laser scanning speed on the microstructure was discussed in the perspective of governing the microstructure by controlling the process parameters. It was shown that the three-dimensional (3D) zig-zag solidification texture observed in the LPBF 316 L was related to the laser scanning strategy. The thermal stability of the microstructure was investigated under isothermal annealing conditions. It was shown that the cells formed at solidification started to disappear at about 800 • C, and that this process leads to a substantial decrease in hardness. Colony boundaries, nevertheless, were quite stable, and no significant grain growth was observed after heat treatment at 1050 • C. The observed experimental results are discussed with respect to the fundamental knowledge of the solidification processes, and compared with the existing literature data.

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Section: Influence Of Solidification Conditions On Microstructure Andmentioning

confidence: 95%

Microstructure, Solidification Texture, and Thermal Stability of 316 L Stainless Steel Manufactured by Laser Powder Bed Fusion

Krakhmalev

Fredriksson

Svensson

et al. 2018

Metals

140

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“…Often, the energy density is used as a parameter to quantify the energy input of the laser into the material. The energy density results from the quantities varied in this study according to the following formula for hatched surfaces [10]:…”

Section: Selective Laser Meltingmentioning

confidence: 99%

“…Due to its high strength, the alloy is used in tooling, structural, and aerospace applications [7]. Thus far, most of the publications on 1.2709 in additive manufacturing deal with density, porosity, mechanical properties, and microstructure in general [8,9], whereas only little research has been done regarding hybrid AM [10,11]. Additionally, work has been done on the machining of additively manufactured maraging steel, though not in a hybrid process [12].…”

Section: Introductionmentioning

confidence: 99%

Areal Surface Roughness Optimization of Maraging Steel Parts Produced by Hybrid Additive Manufacturing

2020

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We report on an experimental study and statistical optimization of the surface roughness using design of experiments and the Taguchi method for parts made of 1.2709 maraging steel. We employ a hybrid additive manufacturing approach that combines additive manufacturing by selective laser melting with subtractive manufacturing using milling in an automated process within a single machine. Input parameters such as laser power, scan speed, and hatching distance have been varied in order to improve surface quality of unmachined surfaces. Cutting speed, feed per tooth, and radial depth of cut have been varied to optimize surface roughness of the milled surfaces. The surfaces of the samples were characterized using 3D profilometry. Scan speed was determined as the most important parameter for non-machined surfaces; radial depth of cut was found to be the most significant parameter for milled surfaces. Areal surface roughness S a could be reduced by up to 40% for unmachined samples and by 23% for milled samples as compared to the prior state of the art.

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“…However, a possible issue is that a lack of studies, specifically dealing with the fatigue response of this material, can be still observed in the scientific literature. 22 An interesting and particularly recent study is presented Branco etal, 1 where AISI 18Ni300 samples were involved in a quite extensive low-cycle fatigue campaign. An experimental campaign was aimed at the investigation of the potential impact of the build orientation on fatigue, following heat ageing treatment and machining with 0.5 mm allowance.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of direct metal laser sintering Maraging steel fatigue strength to build orientation and allowance for machining

Croccolo

Agostinis

Fini

et al. 2018

Fatigue Fract Eng Mat Struct

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This work deals with the effect of build orientation and of allowance for machining on DMLS‐produced Maraging Steel MS1. The experimental results, arranged by tools of Design of Experiment, have been statistically processed and compared. The outcomes were that, probably due to effect of the thermal treatment, machining, and material properties, the aforementioned factors do not have a significant impact on the fatigue response. This made it possible to work out a global curve that accounts for all the results, consisting in a high amount of data points. This can be regarded as one of the most complete and reliable fatigue models in the current literature. Fractographic and micrographic studies have been performed as well, to individuate the crack initiation points, usually located at subsurface porosities, and to investigate the location of internal inclusions and the actual martensitic microstructure along the stacking direction and on the build plane.

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Optimization of selective laser melting parameters and influence of post heat treatment on microstructure and mechanical properties of maraging steel

Cited by 240 publications

References 20 publications

Microstructure, Solidification Texture, and Thermal Stability of 316 L Stainless Steel Manufactured by Laser Powder Bed Fusion

Microstructure, Solidification Texture, and Thermal Stability of 316 L Stainless Steel Manufactured by Laser Powder Bed Fusion

Areal Surface Roughness Optimization of Maraging Steel Parts Produced by Hybrid Additive Manufacturing

Sensitivity of direct metal laser sintering Maraging steel fatigue strength to build orientation and allowance for machining

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