CoCr alloy processed by Selective Laser Melting (SLM): effect of Laser Energy Density on microstructure, surface morphology, and hardness

2020 ◽  
Vol 52 ◽  
pp. 106-119 ◽  
Author(s):  
Lavinia Tonelli ◽  
Alessandro Fortunato ◽  
Lorella Ceschini
Keyword(s):  
Energy Density ◽  
Surface Morphology ◽  
Selective Laser Melting ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Laser Melting ◽  
Cocr Alloy

Selective Laser Melting Additive Manufacturing of Novel Aluminum Based Composites With Multiple Reinforcing Phases

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Dongdong Gu ◽  
Fei Chang ◽  
Donghua Dai
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Energy Density ◽  
Selective Laser Melting ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Wear Property ◽  
Laser Melting ◽  
Sic Particles

The selective laser melting (SLM), due to its unique additive manufacturing (AM) processing manner and laser-induced nonequilibrium rapid melting/solidification mechanism, has a promising potential in developing new metallic materials with tailored performance. In this work, SLM of the SiC/AlSi10Mg composites was performed to prepare the Al-based composites with the multiple reinforcing phases. The influence of the SLM processing parameters on the constitutional phases, microstructural features, and mechanical performance (e.g., densification, microhardness, and wear property) of the SLM-processed Al-based composites was studied. The reinforcing phases in the SLM-processed Al-based composites included the unmelted micron-sized SiC particles, the in situ formed micron-sized Al4SiC4 strips, and the in situ produced submicron Al4SiC4 particles. As the input laser energy density increased, the extent of the in situ reaction between the SiC particles and the Al matrix increased, resulting in the larger degree of the formation of Al4SiC4 reinforcement. The densification rate of the SLM-processed Al-based composite parts increased as the applied laser energy density increased. The sufficiently high density (∼96% theoretical density (TD)) was achieved for the laser linear energy density larger than 1000 J/m. Due to the generation of the multiple reinforcing phases, the elevated mechanical properties were obtained for the SLM-processed Al-based composites, showing a high microhardness of 214 HV0.1, a considerably low coefficient of friction (COF) of 0.39, and a reduced wear rate of 1.56 × 10−5 mm3 N−1 m−1. At an excessive laser energy input, the grain size of the in situ formed Al4SiC4 reinforcing phase, both the strip- and particle-structured Al4SiC4, increased markedly. The significant grain coarsening and the formation of the interfacial microscopic shrinkage porosity lowered the mechanical properties of the SLM-processed Al-based composites. These findings in the present work are applicable and/or transferrable to other laser-based powder processing processes, e.g., laser cladding, laser metal deposition, or laser engineered net shaping.

Effect of defocusing distance on the forming quality of inner structure parts manufactured via selective laser melting

2021 ◽  
pp. 095440892110590
Author(s):  
Weipeng Duan ◽  
Meiping Wu ◽  
Jitai Han ◽  
Yiqing Ma ◽  
Peipei Lu ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Selective Laser Melting ◽  
Surface Pressure ◽  
Laser Energy ◽  
Dimensional Accuracy ◽  
Laser Energy Density ◽  
Laser Melting ◽  
Forming Quality

A systematical work was studied to illustrate the influence of defocusing distance on the forming quality of inner structure fabricated by selective laser melting for Ti-6Al-4V alloy. The relationship between defocusing distance and dimensional accuracy, surface roughness as well as flatness was investigated, finite element analysis (FEA) was used to show the temperature distribution. The results show that defocusing distance not only had an impact on laser energy density, but also showed a significant influence on the surface pressure of the metal powder. Smaller defocusing distance (0.0 mm) accompanied with higher molten pool maximum temperature (3262.96°C), powder melting and splashing at the same time. On the contrary, larger defocusing distance leading to unmelted powder and powder bonding, which influences the forming quality of samples. Dimensional accuracy was less affected in 0.0, 1.0, 2.0 mm defocusing distance (5%), but changed dramatically when it is 3.0 mm (22%). In the same condition, similar variation trend of surface roughness (Ra) and flatness was observed, and varying from 5.1 to 27.3 μm and 0.05 to 0.26 mm, respectively. Simultaneously, the bottom surface is less affected, while the other three sides have the opposite situation. Pores and unmelted powder can be seen on the surface, it is the comprehensive effect of laser energy density and surface pressure. It proves that it is feasible to manufacture inner structure by controlling this process parameter during SLM process, the influence mechanism of defocusing distance on forming quality was also illustrated in this work.

scholarly journals Densification Behavior of 316L Stainless Steel Parts Fabricated by Selective Laser Melting by Variation in Laser Energy Density

2016 ◽  
Vol 57 (11) ◽  
pp. 1952-1959 ◽  
Author(s):  
Joon-Phil Choi ◽  
Gi-Hun Shin ◽  
Mathieu Brochu ◽  
Yong-Jin Kim ◽  
Sang-Sun Yang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Energy Density ◽  
Selective Laser Melting ◽  
316L Stainless Steel ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Densification Behavior ◽  
Laser Melting

scholarly journals Selective Laser Melting of Stainless Steel 316L with Face-Centered-Cubic-Based Lattice Structures to Produce Rib Implants

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5962
Author(s):  
Cho-Pei Jiang ◽  
Alvian Toto Wibisono ◽  
Tim Pasang
Keyword(s):  
Energy Density ◽  
Selective Laser Melting ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Face Centered Cubic ◽  
Lattice Structures ◽  
Test Results ◽  
Laser Melting ◽  
Fcc Lattice ◽  
Face Centered

Selective laser melting has a great potential to manufacture biocompatible metal alloy scaffolds or implants with a regulated porosity structure. This study uses five face-centered cubic (FCC) lattice structures, including FCC, FCC-Z, S-FCC, S-FCC-Z, and FCC-XYZ. Specimens with different lattice structures are fabricated using two laser energy densities, 71 J/mm3 and 125 J/mm3. Density, tensile, compressive and flexural test results exhibit the effect of laser parameters and lattice structure geometries on mechanical properties. The higher laser energy density of 125 J/mm3 results in higher properties such as density, strength, and Young’s modulus than the laser energy density of 71 J/mm3. The S-FCC lattice has the lowest density among all lattices. The mechanical tests result show specimen with FCC-XYZ lattice structures fabricated using a laser energy density of 125 J/mm3 meet the tensile properties requirement for human ribs. This structure also meets the requirement in flexural strength performance, but its stiffness is over that of human ribs. The compression test results of lattices are still incomparable due to unavailable compression data of the human ribs. In short, The FCC-XYZ lattice design fabricated by the 125 J/mm3 laser energy density parameter can be used to manufacture customized rib implants.

Selective Laser Melting of Mechanically Alloyed Metastable Al5Fe2 Powders

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Hugo Montiel ◽  
Ben Xu ◽  
Jianzhi Li
Keyword(s):  
Aluminum Alloys ◽  
Energy Density ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Laser Scanning ◽  
Laser Energy ◽  
Scanning Speed ◽  
High Energy ◽  
Laser Energy Density ◽  
Laser Melting

Aluminum alloys, which are high-strength lightweight materials, were processed by selective laser melting (SLM) with high-energy consumption and poor finish due to quick heat dissipation. Previous investigations reported that SLM with 300 W laser power and 500 mm/s scanning speed can process the aluminum alloys, such as Al-Si12 and AlSi10Mg. This work aims to process the powders to alter their properties and to reduce the laser intensity required in the process, and it also reports that the SLM-processed Al–Fe alloys utilize the metastable alloy by mechanical alloying (MA). The elemental Al and Fe powders were first alloyed in a ball mill in a relative short time period (∼15 h) employing high milling intensities, high ball-to-powder ratio (≥20:1), and high milling velocities (≥400 rpm), which produced fine metastable Al–Fe powders, and these powders were processed later by the SLM. The optimum laser power, the scanning speed, hatch distance, and substrate temperature were investigated by a series of experiments. Experimental results indicated that decreasing the laser energy density while increasing the laser scanning speed can benefit for smoother laser hatch lines, and the metastable Al5Fe2 alloy powders can be processed and stabilized under a 200-W laser energy density and a scanning speed of 1000 mm/s. It is expected that the combination of pre-excited materials in a metastable phase will open a new window to optimize the SLM process for aluminum alloys and other metallic alloys.

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