Effect of scanning speed on the solidification process of Al2O3/GdAlO3/ZrO2 eutectic ceramics in a single track by selective laser melting

2019 ◽  
Vol 45 (14) ◽  
pp. 17252-17257
Author(s):  
Haifang Liu ◽  
Haijun Su ◽  
Zhonglin Shen ◽  
Di Zhao ◽  
Yuan Liu ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Solidification Process ◽  
Scanning Speed ◽  
Single Track ◽  
Laser Melting

Track evolution and surface characteristics of selective laser melting Ti6Al4V

2018 ◽  
Vol 24 (9) ◽  
pp. 1554-1562 ◽  
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.

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 Selective Laser Melting of Pre-Alloyed NiTi Powder: Single-Track Study and FE Modeling with Heat Source Calibration

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7486
Author(s):  
Stanislav V. Chernyshikhin ◽  
Denis G. Firsov ◽  
Igor V. Shishkovsky
Keyword(s):  
Heat Source ◽  
Thermal Behavior ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Laser Power ◽  
Scanning Speed ◽  
Fe Modeling ◽  
Single Track ◽  
Laser Melting ◽  
Melt Pool

Unique functional properties such as the low stiffness, superelasticity, and biocompatibility of nickel–titanium shape-memory alloys provide many applications for such materials. Selective laser melting of NiTi enables low-cost customization of devices and the manufacturing of highly complex geometries without subsequent machining. However, the technology requires optimization of process parameters in order to guarantee high mass density and to avoid deterioration of functional properties. In this work, the melt pool geometry, surface morphology, formation mode, and thermal behavior were studied. Multiple combinations of laser power and scanning speed were used for single-track preparation from pre-alloyed NiTi powder on a nitinol substrate. The experimental results show the influence of laser power and scanning speed on the depth, width, and depth-to-width aspect ratio. Additionally, a transient 3D FE model was employed to predict thermal behavior in the melt pool for different regimes. In this paper, the coefficients for a volumetric double-ellipsoid heat source were calibrated with bound optimization by a quadratic approximation algorithm, the design of experiments technique, and experimentally obtained data. The results of the simulation reveal the necessary conditions of transition from conduction to keyhole mode welding. Finally, by combining experimental and FE modeling results, the optimal SLM process parameters were evaluated as P = 77 W, V = 400 mm/s, h = 70 μm, and t = 50 μm, without printing of 3D samples.

Geometrical feature analysis of Co-Cr-Mo single tracks after selective laser melting processing

2015 ◽  
Vol 21 (3) ◽  
pp. 287-300 ◽  
Author(s):  
Karla Monroy ◽  
Jordi Delgado ◽  
Lidia Sereno ◽  
Joaquim Ciurana ◽  
Nicolas J Hendrichs
Keyword(s):  
Selective Laser Melting ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Single Track ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Content Type ◽  
Dimensional Precision ◽  
Morphologic Characteristics ◽  
Definition Of

Purpose – Therefore, the purpose of this study is to understand the relationships between the processing parameters and the geometric form of the produced single tracks, in order to control dimensional quality in future experimentations. The quality of the deposited single track and layer is of prime importance in the selective laser melting (SLM) process, as it affects the product quality in terms of dimensional precision and product performance. Design/methodology/approach – In this paper, a vertical milling machining center equipped with an Ytterbium-fiber laser was used in the SLM experimentation to form single cobalt-chromium-molybdenum (CoCrMo) tracks. The different geometric features and the influence of the scanning parameters on these morphologic characteristics were studied statistically by means of ANOVA. Findings – Evidently, track height (h1) inaccuracy reduced in layer thicknesses between 100 and 200 μm. The re-melt depth (h2) was determined by the energy parameters, with laser power of 325-350 W and scanning speed (SS) of 66.6-83.3 mm/s being the most favorable parameters to obtain the required anchoring. Moreover, a contact angle of 117° was proposed as optimal, as it permitted an adequate overlapping region and a full densification, and, finally, an SS of 50 mm/s and a layer thickness of 250 were suggested for its development. Originality/value – The comprehension of the phenomena inherent to the process is related to the single track geometrical characteristics, which allow the definition of an optimal value for each factor for a further proposal of processing conditions that can finally derive a higher precision, wetting, density and mechanical properties.

scholarly journals Influence of the Main Parameters of Selective Laser Melting on Stability of Single Track Formation when ‘Growing’ Parts from Copper Alloys

2019 ◽  
pp. 20-29 ◽  
Author(s):  
A.G. Grigoriyants ◽  
D.S. Kolchanov ◽  
A.A. Drenin ◽  
A.O. Denezhkin
Keyword(s):  
Selective Laser Melting ◽  
Copper Alloys ◽  
Melting Process ◽  
Scanning Speed ◽  
Single Track ◽  
Optimal Parameters ◽  
Laser Melting ◽  
Track Formation ◽  
The Stability ◽  
Lower Limits

Selective laser melting technology has the ability to directly produce finished parts, and is economically efficient for single or small batch production. Copper and its alloys are of great interest due to their high thermal and electrical conductivity. The influence of build process parameters, such as scanning speed and layer thickness on the stability of single track formation using a heat-resistant copper alloy PR-BrKh was investigated in this paper. The mechanism of single track formation was studied. As a result, patterns of formation of a stable single track were established, the upper and lower limits of the build parameters were determined. The results of the study provide a deeper understanding of the copper alloys selective laser melting process and may serve as a basis for determining the optimal parameters’ range for ‘growing’ solid structures.

scholarly journals Influence of the conditions of selective laser melting on evaporation

2018 ◽  
Vol 224 ◽  
pp. 01060 ◽  
Author(s):  
Roman S. Khmyrov ◽  
Cyrill E. Protasov ◽  
Andrey V. Gusarov
Keyword(s):  
Mass Transfer ◽  
Selective Laser Melting ◽  
Coming Out ◽  
Thermal Field ◽  
Mass Transfer Process ◽  
Scanning Speed ◽  
Single Track ◽  
Laser Melting ◽  
Quality Properties ◽  
Kinetics Of

The paper presents the results of optical diagnostics of evaporation and displacement of powder fractions during the formation of a single track in the process of selective laser melting. The velocity of the powder fractions is estimated. It was defined, that an increase in the scanning speed leads to an decrease in the particle coming out rate from the molten pool and the rate at which they are attracted. The results allow evaluating the kinetics of the mass-transfer process during selective laser melting. It was clearly shown the material quality properties after the selective laser melting are strongly influenced by the formed thermal field in the laser-irradiated zone.

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