Evolution mechanism of surface morphology and internal hole defect of 18Ni300 maraging steel fabricated by selective laser melting

Abstract Additive manufacturing process of maraging steel has been studied for high value parts in aerospace and automotive industries. The hybrid additive / subtractive manufacturing is effective to achieve tight tolerances and surface finishes. The additive process induces anisotropic mechanical properties of maraging steel, which depends on the laser scanning direction. Because anisotropy in the workpiece material has an influence on the cutting process, the surface finish and the dimension accuracy change according to the direction of the cutter feed with respect to the laser scanning direction. Therefore, the cutting parameters should be determined to control the cutting force considering material anisotropy. The paper discusses the cutting force in milling of maraging steel stacked with selective laser melting, as an additive manufacturing process. Anisotropic effect on the cutting forces is proved with the changing rate of the cutting force in milling of the workpieces stacked by repeating laser scanning at 0/90 degrees and 45/-45 degrees. The cutting forces, then, are analyzed in the chip flow models with piling up of orthogonal cuttings. The force model associates anisotropy with the shear stress on the shear plane. The changes in the cutting forces with the feed direction are discussed in the cutting tests and analysis.

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Track evolution and surface characteristics of selective laser melting Ti6Al4V

Rapid Prototyping Journal ◽

10.1108/rpj-01-2018-0004 ◽

2018 ◽

Vol 24 (9) ◽

pp. 1554-1562 ◽

Cited By ~ 4

Author(s):

Luo Zhang ◽

Haihong Zhu ◽

Jiahe Liu ◽

Xiaoyan Zeng

Keyword(s):

Surface Morphology ◽

Selective Laser Melting ◽

Surface Characteristics ◽

Scanning Speed ◽

Bulk Sample ◽

Three Dimension ◽

Single Track ◽

Heat Accumulation ◽

Laser Melting ◽

Content Type

Purpose The purpose of this paper is to investigate the track evolution and surface characteristics of selective laser melting Ti6Al4V. Design/methodology/approach In the present paper, Ti6Al4V single-track, multi-track and bulk sample were formed at different scanning speed by selective laser melting (SLM). Then, the surface morphology, three-dimension profile and surface roughness were evaluated. The width of the single and multi-track was measured and compared. Findings The results showed that the heat accumulation played a great role on the evolution of tracks and surface characteristics from single-track to multi-track and to bulk. The surface morphology of the subsequent tracks became more regular when the single-track was irregular at the same high scanning speed. The width of last track Wn was always larger than that of the first track W1. The Ra of the top of the bulk increased with the increase of the scanning speed, this trend was as same as the Ra of the single-track, but the trend of Ra of the side was opposite. Originality/value The effect of heat accumulation on the track evolution and surface characteristics is obtained. The results can help to derive a smooth surface with a regular and continuous track in SLM.

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Anisotropic Cutting Force Characteristics in Milling of Maraging Steel Processed Through Selective Laser Melting

Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation ◽

10.1115/msec2021-63704 ◽

2021 ◽

Author(s):

Shoichi Tamura ◽

Takashi Matsumura ◽

Atsushi Ezura ◽

Kazuo Mori

Keyword(s):

Additive Manufacturing ◽

Cutting Force ◽

Maraging Steel ◽

Selective Laser Melting ◽

Cutting Forces ◽

Manufacturing Process ◽

Laser Scanning ◽

Force Model ◽

Laser Melting ◽

Scanning Direction

Abstract Additive manufacturing process of maraging steel has been studied for high value parts in aerospace and automotive industries. The hybrid additive / subtractive manufacturing is effective to achieve tight tolerances and surface finishes. The additive process induces anisotropic mechanical properties of maraging steel, which depends on the laser scanning direction. Because anisotropy in the workpiece material has an influence on the cutting process, the surface finish and the dimension accuracy change according to the direction of the cutter feed with respect to the laser scanning direction. Therefore, the cutting parameters should be determined to control the cutting force considering material anisotropy. The paper discusses the cutting force in milling of maraging steel stacked with selective laser melting, as an additive manufacturing process. Anisotropic effect on the cutting forces is proved with the changing rate of the cutting force in milling of the workpieces stacked by repeating laser scanning at 0/90 degrees and 45/−45 degrees. The cutting forces, then, are analyzed in the chip flow models with piling up of orthogonal cuttings. The force model associates anisotropy with the shear stress on the shear plane. The changes in the cutting forces with the feed direction are discussed in the cutting tests and analysis.

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Hydrogen Embrittlement Behavior of 18Ni 300 Maraging Steel Produced by Selective Laser Melting

Materials ◽

10.3390/ma12152360 ◽

2019 ◽

Vol 12 (15) ◽

pp. 2360 ◽

Cited By ~ 2

Author(s):

Young Jin Kwon ◽

Riccardo Casati ◽

Mauro Coduri ◽

Maurizio Vedani ◽

Chong Soo Lee

Keyword(s):

Hydrogen Embrittlement ◽

Maraging Steel ◽

Selective Laser Melting ◽

Solution Treatment ◽

Tensile Tests ◽

Constant Current ◽

Hydrogen Atoms ◽

Laser Melting ◽

Constant Current Density ◽

Hydrogen Charging

A study was performed to investigate the hydrogen embrittlement behavior of 18-Ni 300 maraging steel produced by selective laser melting and subjected to different heat treatment strategies. Hydrogen was pre-charged into the tensile samples by an electro-chemical method at the constant current density of 1 A m−2 and 50 A m−2 for 48 h at room temperature. Charged and uncharged specimens were subjected to tensile tests and the hydrogen concentration was eventually analysed using quadrupole mass spectroscopy. After tensile tests, uncharged maraging samples showed fracture surfaces with dimples. Conversely, in H-charged alloys, quasi-cleavage mode fractures occurred. A lower concentration of trapped hydrogen atoms and higher elongation at fracture were measured in the H-charged samples that were subjected to solution treatment prior to hydrogen charging, compared to the as-built counterparts. Isothermal aging treatment performed at 460 °C for 8 h before hydrogen charging increased the concentration of trapped hydrogen, giving rise to higher hydrogen embrittlement susceptibility.

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