scholarly journals Research on the Effect of Key Technological Parameters on Molten Pool during Selective Laser Melting Processing

2021 ◽  
Vol 2097 (1) ◽  
pp. 012016
Author(s):  
Wentong Wang ◽  
Linfeng Tang ◽  
Congyan Chen ◽  
Yu Li ◽  
Tao Zhou
Keyword(s):  
Temperature Field ◽  
Selective Laser Melting ◽  
Molten Pool ◽  
Laser Power ◽  
Reference Value ◽  
Scanning Speed ◽  
Ansys Software ◽  
Technological Parameters ◽  
Laser Melting ◽  
Forming Process

Abstract Selective laser melting (SLM), as an emerging technology in additive manufacturing, often has various defects in the forming process. To ensure the consistency and stability of the parts forming quality, the effects of two typical technological parameters, laser power and scanning speed, on the temperature of molten pool are investigated in this paper. Firstly, the temperature field of Ti-6Al-4V is simulated theoretically via ANSYS software, and the effects of two typical technological parameters on the temperature field are studied. Then, in the experiment, using the designed radiation monitoring device and Ti-6Al-4V powder as forming material, the influence of these two typical factors on the state of molten pool is studied. The simulation and experimental results show that the temperature of molten pool shows positive correlation with the laser power and negative correlation with the scanning speed. This will provide a certain reference value for upgrading and optimizing SLM equipment.

scholarly journals Numerical Simulation of Moving Heat Flux during Selective Laser Melting of AlSi25 Alloy Powder

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 877
Author(s):  
Cong Ma ◽  
Xianshun Wei ◽  
Biao Yan ◽  
Pengfei Yan
Keyword(s):  
Numerical Simulation ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Molten Pool ◽  
Laser Power ◽  
Scanning Speed ◽  
Powder Layer ◽  
Maximum Temperature ◽  
Three Dimensional Model ◽  
Laser Melting

A single-layer three-dimensional model was created to simulate multi-channel scanning of AlSi25 powder in selective laser melting (SLM) by the finite element method. Thermal behaviors of laser power and scanning speed in the procedure of SLM AlSi25 powder were studied. With the increase of laser power, the maximum temperature, size and cooling rate of the molten pool increase, while the scanning speed decreases. For an expected SLM process, a perfect molten pool can be generated using process parameters of laser power of 180 W and a scanning speed of 200 mm/s. The pool is greater than the width of the scanning interval, the depth of the molten pool is close to scan powder layer thickness, the temperature of the molten pool is higher than the melting point temperature of the powder and the parameters of the width and depth are the highest. To confirm the accuracy of the simulation results of forecasting excellent process parameters, the SLM experiment of forming AlSi25 powder was carried out. The surface morphology of the printed sample is intact without holes and defects, and a satisfactory metallurgical bond between adjacent scanning channels and adjacent scanning layers was achieved. Therefore, the development of numerical simulation in this paper provides an effective method to obtain the best process parameters, which can be used as a choice to further improve SLM process parameters. In the future, metallographic technology can also be implemented to obtain the width-to-depth ratio of the SLM sample molten pool, enhancing the connection between experiment and theory.

Effects of the Processing Parameters on the Forming Quality of Stainless Steel Parts by Selective Laser Melting

2011 ◽  
Vol 189-193 ◽  
pp. 3668-3671 ◽  
Author(s):  
Qing Song Wei ◽  
Xiao Zhao ◽  
Li Wang ◽  
Rui Di Li ◽  
Jie Liu ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Selective Laser Melting ◽  
Molten Pool ◽  
Laser Power ◽  
Single Layer ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Powder Layer ◽  
Laser Melting

Selective Laser Melting (SLM) can produce high-performance metal parts with complex structures. However, it’s difficult to control the processing parameters, because many factors involves. From the perspective of the molten pool, the study focuses on the effects of processing parameters, including scanning speed, laser power, scanning space, layer thickness, and scanning strategies, on the surface quality, the balling effect, the density of SLM parts, by conducting experiments of single track, single layer and block forming. The results show that the quality of the molten pool is affected by laser power and scanning speed. Scanning drove in the strategy of “jumping and turning”，a smooth surface and a less balling effect will be obtained. The thicker the powder layer is, the lower density will be obtained. The optimal parameters from series of experiments are: laser power of 98W; scanning speed of 90mm/s; scanning space of 0.07mm; layer thickness of 0.1mm; and scanning strategy of “jumping and turning”.

Evaluation of Physicomechanical Properties of Ti-45Nb Specimens Obtained by Selective Laser Melting

2017 ◽  
Vol 743 ◽  
pp. 9-12
Author(s):  
Zhanna G. Kovalevskaya ◽  
Margarita A. Khimich ◽  
Andrey V. Belyakov
Keyword(s):  
Young’S Modulus ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Young's Modulus ◽  
Scanning Speed ◽  
Physicomechanical Properties ◽  
Optical Methods ◽  
Laser Melting ◽  
Average Value ◽  
Hardness Tester

Porosity, values of nanohardness and Young’s modulus of the specimens obtained with the method of selective laser melting were measured with optical methods, scanning electron microscopy and Nano Hardness Tester NHT-S-AX-000X device for measuring physicomechanical properties. Ti-45wt%Nb powder obtained with mechanical alloying was used for selective laser melting. The results have shown that increased heat input due to the laser power growth up to 80 W and scanning speed decrease down to 40 mm/s decreases the porosity of the specimen. The nanohardness average value is not sensitive to the changes of scanning modes in the investigated range. The Young’s modulus decreases with energy input increase.

scholarly journals Collaborative Optimization on Density and Surface Roughness of 316L Stainless Steel in Selective Laser Melting

2020 ◽  
Author(s):  
Yong Deng ◽  
Zhongfa Mao ◽  
Nan Yang ◽  
Xiaodong Niu ◽  
Xiangdong Lu
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Laser Power ◽  
316L Stainless Steel ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Collaborative Optimization ◽  
Laser Melting

Although the concept of additive manufacturing has been proposed for several decades, momentum of selective laser melting (SLM) is finally starting to build. In SLM, density and surface roughness, as the important quality indexes of SLMed parts, are dependent on the processing parameters. However, there are few studies on their collaborative optimization in SLM to obtain high relative density and low surface roughness simultaneously in the previous literature. In this work, the response surface method was adopted to study the influences of different processing parameters (laser power, scanning speed and hatch space) on density and surface roughness of 316L stainless steel parts fabricated by SLM. The statistical relationship model between processing parameters and manufacturing quality is established. A multi-objective collaborative optimization strategy considering both density and surface roughness is proposed. The experimental results show that the main effects of processing parameters on the density and surface roughness are similar. It is noted that the effects of the laser power and scanning speed on the above objective quality show highly significant, while hatch space behaves an insignificant impact. Based on the above optimization, 316L stainless steel parts with excellent surface roughness and relative density can be obtained by SLM with optimized processing parameters.

Effect of processing parameters on forming defects during selective laser melting of AlSi10Mg powder

2020 ◽  
Vol 26 (5) ◽  
pp. 871-879 ◽  
Author(s):  
Haihua Wu ◽  
Junfeng Li ◽  
Zhengying Wei ◽  
Pei Wei
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Argon Pressure ◽  
Powder Layer ◽  
Laser Melting ◽  
Content Type ◽  
Scan Speed ◽  
Forming Defects

Purpose To fabricate a selective laser melting (SLM)-processed AlSi10Mg part with almost full density and free of any apparent pores, this study aims to investigate the effect of ambient argon pressure and laser scanning speed on the particles splash during the AlSi10Mg powder bed laser melting. Design/methodology/approach Based on the discrete element method (DEM), a 3D model of random distribution of powder particles was established, and the 3D free surface of SLM forming process was dynamically tracked by the volume of fluid, where a Gaussian laser beam acts as the energy source melting the powder bed. Through the numerical simulation and process experimental research, the effect of the applied laser power and scanning speed on the operating laser melting temperature was studied. Findings The process stability has a fundamental role in the porosity formation, which is process-dependent. The effect of the processing conditions on the process stability and the resultant forming defects were clarified. Research limitations/implications The results shows that the pores were the main defects present in the SLM-processed AlSi10Mg sample, which decreases the densification level of the sample. Practical implications The optimal processing parameters (argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm ) applied during laser melting can improve the quality of selective laser melting of AlSi10Mg, Social implications It can provide a technological support for 3D printing. Originality/value Based on the analysis of the pore and balling formation mechanisms, the optimal processing parameters have been obtained, which were argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm. Then, a near-fully dense sample free of any apparent pores on the cross-sectional microstructure was produced by SLM, wherein the relative density of the as-built samples is larger than 97.5%.

scholarly journals In Situ Mo(Si,Al)2-Based Composite through Selective Laser Melting of a MoSi2-30 wt.% AlSi10Mg Mixture

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3720 ◽  
Author(s):  
Tatevik Minasyan ◽  
Sofiya Aydinyan ◽  
Ehsan Toyserkani ◽  
Irina Hussainova
Keyword(s):  
High Temperature ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Laser Scanning ◽  
Scanning Speed ◽  
Laser Melting ◽  
Structural Applications ◽  
Laser Scanning Speed ◽  
Fusion Approach

The laser power bed fusion approach has been successfully employed to manufacture Mo(Si,Al)2-based composites through the selective laser melting of a MoSi2-30 wt.% AlSi10Mg mixture for high-temperature structural applications. Composites were manufactured by leveraging the in situ reaction of the components during printing at 150–300 W laser power, 500–1000 mm·s−1 laser scanning speed, and 100–134 J·mm−3 volumetric energy density. Microcomputed tomography scans indicated a negligible induced porosity throughout the specimens. The fully dense Mo(Si1-x,Alx)2-based composites, with hardness exceeding 545 HV1 and low roughness for both the top (horizontal) and side (vertical) surfaces, demonstrated that laser-based additive manufacturing can be exploited to create unique structures containing hexagonal Mo(Si0.67Al0.33)2.

scholarly journals Cavitation erosion resistance of 316L stainless steel fabricated using selective laser melting

Friction ◽  
2020 ◽  
Author(s):  
Hongqin Ding ◽  
Qing Tang ◽  
Yi Zhu ◽  
Chao Zhang ◽  
Huayong Yang
Keyword(s):  
Stainless Steel ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Cavitation Erosion ◽  
316L Stainless Steel ◽  
Erosion Resistance ◽  
Scanning Speed ◽  
Laser Melting ◽  
Cavitation Damage ◽  
Cavitation Erosion Resistance

AbstractCavitation erosion degrades the performance and reliability of hydraulic machinery. Selective laser melting (SLM) is a type of metal additive manufacturing technology that can fabricate metal parts directly and provide lightweight design in various industrial applications. However, the cavitation erosion behaviors of SLM-fabricated parts have rarely been studied. In this study, SLM 316L stainless steel samples were fabricated via SLM technology considering the scanning strategy, scanning speed, laser power, and build orientation. The effect of the process parameters on the cavitation erosion resistance of the SLM-fabricated 316L stainless steel samples was illustrated using an ultrasonic vibratory cavitation system. The mass loss and surface topography were employed to evaluate the surface cavitation damage of the SLM-fabricated 316L stainless steel samples after the cavitation test. The cavitation damage mechanism of the SLM-fabricated samples was discussed. The results show that the degree of cavitation damage of the sample fabricated via SLM with a few defects, anisotropic build direction, and columnar microstructure is significantly decreased. Defects such as pores, which are attributed to low laser power and high scanning speed, may severely aggravate the cavitation damage of the SLM-fabricated samples. The sample fabricated via SLM with a low laser power and exposure time exhibited the highest porosity and poor cavitation erosion resistance. The cellular structures are more prone to cavitation damage compared with the columnar structures. A sample with a high density of grain boundaries will severely suffer cavitation damage.

A Study of Keyhole Porosity in Selective Laser Melting: Single-Track Scanning With Micro-CT Analysis

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Subin Shrestha ◽  
Thomas Starr ◽  
Kevin Chou
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Scanning Speed ◽  
Single Track ◽  
Micro Computed Tomography ◽  
Laser Melting ◽  
Pore Characteristics ◽  
Line Energy ◽  
The Individual ◽  
Pore Number

Porosity is an inherent attribute in selective laser melting (SLM) and profoundly degrades the build part quality and its performance. This study attempts to understand and characterize the keyhole pores formed during single-track scanning in SLM. First, 24 single tracks were generated using different line energy density (LED) levels, ranging from 0.1 J/mm to 0.98 J/mm, by varying the laser power and the scanning speed. The samples were then scanned by micro-computed tomography to measure keyhole pores and analyze the pore characteristics. The results show a general trend that the severity of the keyhole porosity increases with the increase of the LED with exceptions of certain patterns, implying important individual contributions from the parameters. Next, by keeping the LED constant in another set of experiments, different combinations of the power and the speed were tested to investigate the individual effect. Based on the results obtained, the laser power appears to have a greater effect than the scanning speed on both the pore number and the pore volume as well as the pore depth. For the same LED, the pore number and volume increase with increasing laser power until a certain critical level, beyond which, both the pore number and volume will decrease, if the power is further increased. For the LED of 0.32 J/mm, 0.4 J/mm, and 0.48 J/mm, the critical laser power that reverses the trend is about 132 W, 140 W, and 144 W, respectively.

Experimental Investigation into the Single-Track of Selective Laser Melting of IN625

2011 ◽  
Vol 233-235 ◽  
pp. 2844-2848 ◽  
Author(s):  
Li Wang ◽  
Qing Song Wei ◽  
Yu Sheng Shi ◽  
Jin Hui Liu ◽  
Wen Ting He
Keyword(s):  
Energy Density ◽  
Relative Density ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Laser Energy ◽  
Scanning Speed ◽  
Single Track ◽  
Laser Melting ◽  
Metallic Parts

Selective laser melting(SLM) is driven by the need to fabricate functional metallic parts and tools with near shape and density. The method of process to fabricate a metal part will save materials, time and energy compared to the traditional manufacturing methods. Unlike the selective laser sintering (SLS), the metal powder particles are molten by the laser beam during the process of selective laser melting. In this paper, IN625 powders were adopted to investigate the characters of single molten track. The factors that affect the surface quality and relative density are the process parameters such as the laser energy, scan speed and so on. They were studied to find out the correlation between the parameters and formation of single-track. It has been found that Optimal ratio between laser power and scanning speed (P/v) is 1-1.5 for IN625 SLM. P/v is the linear energy density. It also has been found that the width and height of single-track can be calculated when the linear energy density is given. In this study the laser power, scan spacing and the hatch spacing which affect the surface quality and the relative density of the metallic parts were optimized.

scholarly journals Microstructure evolution and mechanical properties of Hastelloy X alloy produced by Selective Laser Melting

2020 ◽  
Vol 39 (1) ◽  
pp. 124-135
Author(s):  
Sun Zhonggang ◽  
Ji Shuwei ◽  
Guo Yanhua ◽  
Lu Yichen ◽  
Chang Lili ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Microstructure Evolution ◽  
Laser Power ◽  
Complex Geometry ◽  
Lamellar Microstructure ◽  
Aging Treatment ◽  
Scanning Speed ◽  
Laser Melting ◽  
Columnar Crystal ◽  
Hastelloy X

AbstractSelective laser melting (SLM) is considered as an important additive manufacturing (AM) technology which can fabricate parts with complex geometry. However, it is difficult to predict the optimal SLM-parameters of metallic materials. In this study, orthogonal experiments were designed to study the influence of SLM-process parameters on the density and fabricated quality of Hastelloy X superalloy. Moreover, the relationship between microstructure evolution and performance of deposited microstructure was studied after heat treatment. The laser power, scanning speed and energy density have a significant effect on the density of the fabricated parts. The optimal parameters for determining Hastelloy X are 250 W laser power, 500 mm/s scanning speed, 100 μm hatch space, and 30 μmlayer thickness. The deposited microstructure is a lamellar microstructure in the horizontal direction and a columnar crystal in the longitudinal direction, and the microstructure is mainly martensite. After solid-solution and aging treatment, grain grows up. Martensite decomposes and the carbide M6C was precipitated during the aging process. The strength of the microstructure decreases slightly due to the growth of grain size.

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