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

Materials ◽  
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.

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.

scholarly journals Selective Laser Melting of 18NI-300 Maraging Steel

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4268 ◽  
Author(s):  
Mariusz Król ◽  
Przemysław Snopiński ◽  
Jiří Hajnyš ◽  
Marek Pagáč ◽  
Dariusz Łukowiec
Keyword(s):  
Relative Density ◽  
Maraging Steel ◽  
Selective Laser Melting ◽  
Aging Treatment ◽  
Steel Powder ◽  
Process Conditions ◽  
Laser Melting ◽  
Microstructure Observation ◽  
High Relative Density ◽  
Wide Range

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.

scholarly journals Cracking Behavior of René 104 Nickel-Based Superalloy Prepared by Selective Laser Melting Using Different Scanning Strategies

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2149
Author(s):  
Kai Peng ◽  
Ranxi Duan ◽  
Zuming Liu ◽  
Xueqian Lv ◽  
Quan Li ◽  
...  
Keyword(s):  
Residual Stress ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
High Quality ◽  
Cracking Behavior ◽  
Nickel Based Superalloy ◽  
Size Number ◽  
Cracking Performance ◽  
Scanning Strategies

Eliminating cracks is a big challenge for the selective laser melting (SLM) process of low-weldable Nickel-based superalloy. In this work, three scanning strategies of the snake, stripe partition, and chessboard partition were utilized to prepare René 104 Ni-based superalloy, of which the cracking behavior and the residual stress were investigated. The results showed that the scanning strategies had significant effects on the cracking, residual stress, and relative density of the SLMed René 104 superalloy. The scanning strategies with more partitions boosted the emergence of cracks, as high-density cracks occurred in these samples. The overlapping zone (OZ) of the scanning partition was also susceptible to cracking, which increased the size, number, and density of the cracks. The cracking performance was relatively moderate in the snake-scanned samples, while that in the chessboard-partition-scanned samples was the most severe. It is concluded that the partition scanning strategies induced more cracks in the SLMed René 104 superalloy, of which the residual stress was apparently reduced. Therefore, it is necessary to design scanning strategies with optimized scanning partitions and overlaps to avoid cracking and acquire a high-quality, near fully dense, low-weldable Nickel-based superalloy using SLM.

scholarly journals High Strength X3NiCoMoTi 18-9-5 Maraging Steel Prepared by Selective Laser Melting from Atomized Powder

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4174 ◽  
Author(s):  
Angelina Strakosova ◽  
Jiří Kubásek ◽  
Alena Michalcová ◽  
Filip Průša ◽  
Dalibor Vojtěch ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Maraging Steel ◽  
Selective Laser Melting ◽  
High Strength ◽  
Industrial Applications ◽  
Tensile Yield Strength ◽  
Laser Melting ◽  
Maraging Steels ◽  
3D Printed

Maraging steels are generally characterized by excellent mechanical properties, which make them ideal for various industrial applications. The application field can be further extended by using selective laser melting (SLM) for additive manufacturing of shape complicated products. However, the final mechanical properties are strongly related to the microstructure conditions. The present work studies the effect of heat treatment on the microstructure and mechanical properties of 3D printed samples prepared from powder of high-strength X3NiCoMoTi 18-9-5 maraging steel. It was found that the as-printed material had quite low mechanical properties. After sufficient heat treatment, the hardness of the material increased from 350 to 620 HV0.1 and the tensile yield strength increased from 1000 MPa up to 2000 MPa. In addition, 3% ductility was maintained. This behavior was primarily affected by strong precipitation during processing.

Selective laser melting of polymers: influence of powder coating on mechanical part properties

2018 ◽  
Vol 38 (7) ◽  
pp. 667-674 ◽  
Author(s):  
Maximilian Drexler ◽  
Sandra Greiner ◽  
Matthias Lexow ◽  
Lydia Lanzl ◽  
Katrin Wudy ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Powder Coating ◽  
Mechanical Tests ◽  
Laser Melting ◽  
Part Quality ◽  
Thermal Fields ◽  
Compaction Behavior ◽  
Processing Strategies ◽  
Force Impact ◽  
New Processing

Abstract For the derivation of part quality increasing process strategies, knowledge about interactions between sub-processes of selective laser melting (SLM) and resulting part properties is necessary. The SLM process consists of three major sub-processes: powder coating, exposure, and material consolidation. According to the interaction of sub-processes, resulting processing conditions during SLM determine the part properties by changing micro structural pore number and distribution. In addition to absolute temperatures, the time-dependency of the thermal fields also influences the porosity of molten parts. Present process strategies tend to decrease building time by acceleration of the subprocesses. Apart from prior investigated acceleration of the exposure, the powder coating step is focused. Within the paper, the authors analyze the basic interactions between different coating parameters and part properties. The authors estimate an interaction between coating speed and resulting part properties due to a force impact caused by the moved coating mechanism. Therefore, specimens produced with different coating speeds are analyzed with imaging technologies as well as mechanical tests. Based on the investigations, new processing strategies can be established considering the forces applied to the powder bed during the coating process, as well as the unique compaction behavior of current and future used powders.

ANISOTROPIC CUTTING FORCE CHARACTERISTICS IN MILLING OF MARAGING STEEL PROCESSED THROUGH SELECTIVE LASER MELTING

2021 ◽  
pp. 1-16
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.

scholarly journals Effect of Process Parameters and High-Temperature Preheating on Residual Stress and Relative Density of Ti6Al4V Processed by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 930 ◽  
Author(s):  
Martin Malý ◽  
Christian Höller ◽  
Mateusz Skalon ◽  
Benjamin Meier ◽  
Daniel Koutný ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Residual Stresses ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Stress Reduction ◽  
Laser Melting ◽  
Preheating Temperature ◽  
Laser Velocity

The aim of this study is to observe the effect of process parameters on residual stresses and relative density of Ti6Al4V samples produced by Selective Laser Melting. The investigated parameters were hatch laser power, hatch laser velocity, border laser velocity, high-temperature preheating and time delay. Residual stresses were evaluated by the bridge curvature method and relative density by the optical method. The effect of the observed process parameters was estimated by the design of experiment and surface response methods. It was found that for an effective residual stress reduction, the high preheating temperature was the most significant parameter. High preheating temperature also increased the relative density but caused changes in the chemical composition of Ti6Al4V unmelted powder. Chemical analysis proved that after one build job with high preheating temperature, oxygen and hydrogen content exceeded the ASTM B348 limits for Grade 5 titanium.

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