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.

Theoretical and experimental study on surface roughness of 316L stainless steel metal parts obtained through selective laser melting

2016 ◽  
Vol 22 (4) ◽  
pp. 706-716 ◽  
Author(s):  
Di Wang ◽  
Yang Liu ◽  
Yongqiang Yang ◽  
Dongming Xiao
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Surface Quality ◽  
Theoretical Foundation ◽  
Laser Energy ◽  
Melting Zone ◽  
Laser Energy Density ◽  
Single Track ◽  
Laser Melting ◽  
Content Type

Purpose The purpose of this paper is to provide a theoretical foundation for improving the selective laser melting (SLM) surface roughness. To improve the part’s surface quality during SLM process, the upper surface roughness of SLM parts was theoretically studied and the influencing factors were analyzed through experiments. Design/methodology/approach The characteristics of single track were first investigated, and based on the analysis of single track, theoretical value of the upper surface roughness would be calculated. Two groups of cubic sample were fabricated to validate SLM parts’ surface roughness, the Ra and relative density of all the cubic parts was measured, and the difference between theoretical calculation and experiment results was studied. Then, the effect of laser energy density on surface roughness was studied. At last, the SLM part’s surface was improved by laser re-melting method. At the end of this paper, the curved surface roughness was discussed briefly. Findings The SLM upper surface roughness is affected by the width of track, scan space and the thickness of powder layer. Measured surface roughness Ra value was about 50 per cent greater than the theoretical value. The laser energy density has a great influence on the SLM fabrication quality. Different laser energy density corresponds to different fabricating characteristics. This study divided the SLM fabrication into not completely melting zone, balling zone in low energy density, successfully fabricating zone and excessive melting zone. The laser surface re-melting (LSR) process can improve the surface roughness of SLM parts greatly without considering the fabricating time and stress accumulation. Originality/value The upper surface roughness of SLM parts was theoretically studied, and the influencing factors were analyzed together; also, the LSR process was proven to be effective to improve the surface quality. This study provides a theoretical foundation to improve the surface quality of SLM parts to promote the popularization and application of metal additive manufacturing technology.

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.

scholarly journals Effect of Selective Laser Melting Process Parameters on the Quality of Al Alloy Parts: Powder Characterization, Density, Surface Roughness, and Dimensional Accuracy

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2343 ◽  
Author(s):  
Ahmed Maamoun ◽  
Yi Xue ◽  
Mohamed Elbestawi ◽  
Stephen Veldhuis
Keyword(s):  
Surface Roughness ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Dimensional Accuracy ◽  
High Strength ◽  
Melting Process ◽  
Al Alloys ◽  
Al Alloy ◽  
Laser Melting

Additive manufacturing (AM) of high-strength Al alloys promises to enhance the performance of critical components related to various aerospace and automotive applications. The key advantage of AM is its ability to generate lightweight, robust, and complex shapes. However, the characteristics of the as-built parts may represent an obstacle to the satisfaction of the parts’ quality requirements. The current study investigates the influence of selective laser melting (SLM) process parameters on the quality of parts fabricated from different Al alloys. A design of experiment (DOE) was used to analyze relative density, porosity, surface roughness, and dimensional accuracy according to the interaction effect between the SLM process parameters. The results show a range of energy densities and SLM process parameters for AlSi10Mg and Al6061 alloys needed to achieve “optimum” values for each performance characteristic. A process map was developed for each material by combining the optimized range of SLM process parameters for each characteristic to ensure good quality of the as-built parts. This study is also aimed at reducing the amount of post-processing needed according to the optimal processing window detected.

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
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