Journal articles: 'Melting process on the laser'

1

Sung, M. Y., B. D. Joo, S. H. Kim, and Y. H. Moon. "Process Analysis of Melting Behaviors in Selective Laser Melting Process." Transactions of Materials Processing 19, no. 8 (December 1, 2010): 517–22. http://dx.doi.org/10.5228/kstp.2010.19.8.517.

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Hagedorn, Yves, and Felix Pastors. "Process Monitoring of Laser Beam Melting." Laser Technik Journal 15, no. 2 (April 2018): 54–57. http://dx.doi.org/10.1002/latj.201800009.

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van Belle, Laurent, and Alban Agazzi. "Inverse Thermal Analysis of Melting Pool in Selective Laser Melting Process." Key Engineering Materials 651-653 (July 2015): 1519–24. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.1519.

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The Selective Laser Melting (SLM) process of metallic powder is an additive technology. It allows the production of complex-shaped parts which are difficult to obtain by conventional methods. The principle is similar to Selective Laser Sintering (SLS) process: it consists, from an initial CAD model, to create the desired part layer by layer. The laser scans a powder bed of 40 μm thick. The irradiated powder is instantly melted and becomes a solid material when the laser moves away. A new layer of powder is left and the laser starts a new cycle of scanning. The sudden and intense phase changing involves high thermal gradients which induce contraction and expansion cycles in the part. These cycles results in irreversible plastic strains. The presence of residual stresses in the manufactured part can damage the mechanical properties, such as the fatigue life. This study focuses on the thermal and mechanical modelling of the SLM process. One of the key points of the mechanical modelling is the determination of the heat source generated by the laser in order to predict residual stresses. This work is divided in three parts. In a first part, an experimental protocol is established in order to measure the temperature variation during the process. In the second part, a thermal model of the process is proposed. Finally, an inverse method to determine the power and the shape of the heat source is developed. Experimental and computational results are fitted. The influence of several geometries of the heat source is investigated.

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Thombansen, Ulrich, Alexander Gatej, and Milton Pereira. "Process observation in fiber laser–based selective laser melting." Optical Engineering 54, no. 1 (October 8, 2014): 011008. http://dx.doi.org/10.1117/1.oe.54.1.011008.

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Sakai, Yasunori, Wataru Ichikawa, and Tomohisa Tanaka. "Novel laser melting stir process for microwelding." Manufacturing Letters 25 (August 2020): 6–9. http://dx.doi.org/10.1016/j.mfglet.2020.05.004.

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Sukumar, S., and S. P. Kar. "Parametric Analysis of Pulsed Laser Melting Process." IOP Conference Series: Materials Science and Engineering 338 (March 2018): 012009. http://dx.doi.org/10.1088/1757-899x/338/1/012009.

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Xiao, Hai Bing. "Research on Laser Oxidation Melting Cutting Process of Automobile Carbon Parts." Applied Mechanics and Materials 778 (July 2015): 159–63. http://dx.doi.org/10.4028/www.scientific.net/amm.778.159.

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This paper deals with the study of automobile parts laser cutting process and high power laser oxidation melting cutting technology. Laser oxidation melting cutting and perforation technology was studied and laser cutting process was established. Take automobile part back end plate for example, back end plate and the material is carbon steel, the CAD/CAM simulation software was used, reasonable processing parameters, cutting parameters and perforation parameters were designed. The experimental results show that laser oxidation cutting is very effective method for automobile parts of carbon steel. The laser oxidation laser cutting technical problems and carbon materials processing technology were solved and improvement measures were summarized for the high laser oxidation melting cutting.

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C. Tseng, W., and J. N. Aoh. "Experimental Validation of a Laser Heat Source Model for Laser Melting and Laser Cladding Processes." Open Mechanical Engineering Journal 8, no. 1 (October 9, 2014): 370–81. http://dx.doi.org/10.2174/1874155x01408010370.

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Selective laser melting (SLM) and laser cladding are laser additive manufacturing methods that have been developed for application to the near-net-shape process and 3D printing. The temperature distributions and track profiles of SLM and clad layers require additional in-depth investigation to optimize manufacturing processes. This research involved developing a tailored laser heat source model that contains a comprehensive selection of laser beam characteristics and can be used in finite element analysis of the laser melting process. This paper presents a systematic experimental validation of the applicability of the proposed laser heat source model to single-track Nd:YAG and CO2 laser melting simulations. The evolution of the melt pool isotherms and the variation in track profiles caused by adjusting the laser power and scanning speed were numerically predicted and experimentally verified. Appropriate process parameters and the threshold power for continuous track layer formation were determined. The balling phenomenon on preplaced powder was observed at power levels below the threshold values. Nd:YAG laser melting resulted in a wide and shallow track profile, which was adequately predicted using the numerical simulation. CO2 laser melting resulted in a triangular track profile, which deviated slightly from the finite element prediction. The results indicated a high level of consistency between the experimental and the numerical results regarding track depth evolution, whereas the numerically predicted track width evolution deviated slightly from the experimentally determined track width evolution. This parametric laser melting study validated the applicability of the proposed laser heat source model in numerical analysis of laser melting processes such as SLM and laser cladding.

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Ridolfi, Maria Rita, Paolo Folgarait, and Andrea Di Schino. "MODELLING OF SELECTIVE LASER MELTING PROCESS FOR ADDITIVE MANUFACTURING." Acta Metallurgica Slovaca 26, no. 1 (March 18, 2020): 7–10. http://dx.doi.org/10.36547/ams.26.1.525.

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The proposed model is a numerical tool for designing processing windows suitable to metal alloy. The model is validated fitting experimental measures of track width, depth and cross sectional area from three literature sources. Effective liquid pool thermal conductivity laser absorptivity and depth of application of laser energy are here considered as fitting parameters. Laser absorptivity and depth of application of laser energy result to rise almost linearly with increasing specific energy.. The obtained results give confidence about the possibility of using the model as a predicting tool after further calibration on a wider range of metal alloys.

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Lykov, P. A., E. V. Safonov, and A. M. Akhmedianov. "Selective Laser Melting of Copper." Materials Science Forum 843 (February 2016): 284–88. http://dx.doi.org/10.4028/www.scientific.net/msf.843.284.

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In this work the selective laser melting (SLM) of pure copper powder was studied. Because of low laser radiation absorption and high thermal conductivity it is very difficult to organize stable SLM process for copper. Five 10x10x5 mm specimens were fabricated by using different process parameters (scanning speed, point distance, exposure time, scanning strategy). The structure of fabricated specimens was studied by scanning electron microscopy of polished cross-sections. The tensile test was carried out for SLM regime with the lowest porosity.

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Le, K. Q., C. Tang, and C. H. Wong. "On the study of keyhole-mode melting in selective laser melting process." International Journal of Thermal Sciences 145 (November 2019): 105992. http://dx.doi.org/10.1016/j.ijthermalsci.2019.105992.

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Yadroitsev, I., Ph Bertrand, and I. Smurov. "Parametric analysis of the selective laser melting process." Applied Surface Science 253, no. 19 (July 2007): 8064–69. http://dx.doi.org/10.1016/j.apsusc.2007.02.088.

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Jin, Biao, Min Li, TaeWoo Hwang, and YoungHoon Moon. "Feasibility Studies on Underwater Laser Surface Hardening Process." Advances in Materials Science and Engineering 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/845273.

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Laser surface hardening process is a very promising hardening method for ferrous and nonferrous alloys where transformations occur during cooling after laser melting in the solid state. This study experimentally characterizes laser surface hardening of tool steel in both water and air. For the underwater operation, laser surface scanning is performed over the tool steel surface which is immersed in water. The laser surface hardening tests are performed with a maximum 200 W fiber laser with a Gaussian distribution of energy in the beam. For the surface hardening, single-track melting experiment which sequentially scans elongated path of single line has been performed. As the hardened depth depends on the thermal conductivity of the material, the surface temperature and the penetration depth may be varied by underwater laser processing. The feasibility of underwater laser surface hardening process is discussed on the basis of average hardness level and hardened bead shape.

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Taheri Andani, Mohsen, Reza Dehghani, Mohammad Reza Karamooz-Ravari, Reza Mirzaeifar, and Jun Ni. "Spatter formation in selective laser melting process using multi-laser technology." Materials & Design 131 (October 2017): 460–69. http://dx.doi.org/10.1016/j.matdes.2017.06.040.

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Wang, Y. S., Juan Juan Wang, J. B. Lei, and Xi Chen Yang. "Study on Measurement of Melting Process of Molten Pool Formed by Laser Scanning Mirror." Key Engineering Materials 392-394 (October 2008): 141–45. http://dx.doi.org/10.4028/www.scientific.net/kem.392-394.141.

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The profile and temperature distribution of laser molten pool are mainly factors which have directly effect on quality of laser processing (laser melting and laser cladding). It is very necessary to study measurement method of melting process in laser molten poo1 on-line, for improving processing design and inspecting laser processing quality. A system of dynamic process measurement for laser molten pool was developed. The melting process of laser scanning molten pool formed by high power CO2 Laser was measured. Its temperature distribution was analyzed by special analysis software. It was shown that a section of integrated molten pool would come into being in the middle of the laser scanning line spot after a period of scanning time, and then the molten pool got increased in length with the time, and a little increased in width at the same time, the result was consistent with that of computer numerical simulation. Compared with laser focusing spot, laser scanning spot was more uniform in temperature distribution, that could be propitious to improve the quality of laser processing.

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Hwang, Tae Woo, Young Yun Woo, Sang Wook Han, and Young Hoon Moon. "Fabrication of Mesh Patterns Using a Selective Laser-Melting Process." Applied Sciences 9, no. 9 (May 10, 2019): 1922. http://dx.doi.org/10.3390/app9091922.

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The selective laser-melting (SLM) process can be applied to the additive building of complex metal parts using melting metal powder with laser scanning. A metal mesh is a common type of metal screen consisting of parallel rows and intersecting columns. It is widely used in the agricultural, industrial, transportation, and machine protection sectors. This study investigated the fabrication of parts containing a mesh pattern from the SLM of AISI 304 stainless steel powder. The formation of a mesh pattern has a strong potential to increase the functionality and cost-effectiveness of the SLM process. To fabricate a single-layered thin mesh pattern, laser layering has been conducted on a copper base plate. The high thermal conductivity of copper allows heat to pass through it quickly, and prevents the adhesion of a thin laser-melted layer. The effects of the process conditions such as the laser scan speed and scanning path on the size and dimensional accuracy of the fabricated mesh patterns were characterized. As the analysis results indicate, a part with a mesh pattern was successfully obtained, and the application of the proposed method was shown to be feasible with a high degree of reliability.

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Maeshima, Takashi, Keiichiro Oh-Ishi, Hiroaki Kadoura, and Masashi Hara. "Microstructure Characterization of AlSi10Mg Fabricated by Selective Laser Melting Process." Materials Science Forum 941 (December 2018): 1437–42. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1437.

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Multi-scale microstructure observation and three dimensional finite element thermal analysis of AlSi10Mg alloy fabricated by selective laser melting (SLM) process were demonstrated in order to understand the microstructure formation process during SLM fabrication. The unique hierarchically microstructures were observed: (1) the “fish scale” microstructure corresponding to a part of molten pool consists of columnar and equiaxed grains and (2) these grains contain a substructure of α-Al surrounded by Si particles. It is revealed that a supersaturated Si concentration due to the predicted rapid cooling rate on the order of 106 oC/s. In addition, the base temperature during the fabrication increases gradually with some peak temperature of each laser path as the laser scan has proceeded on a powder layer. Although the thermal changes cause no melting of the AlSi10Mg except directly fused region by selective laser so called molten pool, those are capable of causing precipitation and/or clustering.

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Saprykin, Alexander A., Yuriy P. Sharkeev, Natalya A. Saprykina, and Egor A. Ibragimov. "Selective Laser Melting of Magnesium." Key Engineering Materials 839 (April 2020): 144–49. http://dx.doi.org/10.4028/www.scientific.net/kem.839.144.

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Magnesium-based materials find their use mainly in manufacturing light-weight constructions in motor-car, airspace industries, and biomedicine due to the low density. This paper provides an overview of introducing magnesium into SLM technology and describes searching experiments to prepare samples of magnesium powder МPF-4 (Russian State Standard 6001-79) conducted in the Laboratory of Yurga Institute of Technology. The study has determined appropriate parameters to synthesize a compact structure: laser output power 100 W, laser beam movement velocity 200 mm/s, scanning pitch 0.1 mm, modulation frequency of laser irradiation m = 2500 Hz, linear energy density Е=5 J/mm2, the process is to be carried out in argon shielding medium.

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Jia, Yan Ping, and Nan Hai Hao. "Effects of Process Variables on Temperature Field of Laser Cladding." Applied Mechanics and Materials 197 (September 2012): 764–67. http://dx.doi.org/10.4028/www.scientific.net/amm.197.764.

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Laser cladding utilizes a laser as energy source to apply a layer of a desired material onto a substrate. As a complex thermal-mechanical process, laser cladding is not quite understood yet. In this paper, effects of process variables on temperature variation during laser cladding are investigated with finite element method. The powder feeding during cladding is taken into account by using the element’s functions of “death” and “birth”. This makes the analysis more accurately. The analysis results show that the maximum temperature at the melting pool during cladding is directly proportional to the laser power and preheated temperature. The maximum cooling rate at the melting pool is inversely proportional to them. Increasing the preheated temperature can decrease the cooling rate of the clayed layer effectively. Increasing the laser power can also decrease the cooling rate, but the effect is not obvious.

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Wang, Jian-Hong, Jie Ren, Wei Liu, Xiao-Yu Wu, Ming-Xiang Gao, and Pei-Kang Bai. "Effect of Selective Laser Melting Process Parameters on Microstructure and Properties of Co-Cr Alloy." Materials 11, no. 9 (August 27, 2018): 1546. http://dx.doi.org/10.3390/ma11091546.

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Due to the rapid melting and solidification mechanisms involved in selective laser melting (SLM), CoCrMo alloys fabricated by SLM differ from the cast form of the same alloy. In this study, the relationship between process parameters and the morphology and macromechanical properties of cobalt-chromium alloy micro-melting pools is discussed. By measuring the width and depth of the molten pool, a theoretical model of the molten pool is established, and the relationship between the laser power, the scanning speed, the scanning line spacing, and the morphology of the molten pool is determined. At the same time, this study discusses the relationship between laser energy and molding rate. Based on the above research, the optimal process for the laser melting of cobalt-chromium alloy in the selected area is obtained. These results will contribute to the development of biomedical CoCr alloys manufactured by SLM.

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Slodczyk, Marcel, Alexander Ilin, Thomas Kiedrowski, Jens Schmiemann, and Vasily Ploshikhin. "Simulation Aided Process Development with Multi-Spot Strategies in Laser Powder-Bed Fusion." Advanced Materials Research 1161 (March 2021): 75–82. http://dx.doi.org/10.4028/www.scientific.net/amr.1161.75.

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A challenge in laser powder-bed fusion is to achieve high process speed while maintaining quality level of the melting tracks. One approach to increase productivity is to distribute available laser power over several laser spots, resulting in higher melting rate. Using multiple laser spots opens up new parameter spaces in comparison to the conventional single-spot exposure. In addition to classical process parameters, e.g. total laser power and scanning speed, the distribution of power to the specific spots and the respective spatial arrangement have an impact on resulting process quality and speed. Within the scope of this research work, a physically based model is presented to define multi-spot process strategies for the generation of desired melt pool dimensions. Diffractive optical elements are used in order to adjust power or spatial arrangement of multiple laser spots. Resulting melt pool has more width and less depth compared to single-spot generated melt pools. Simulations and experiments show an optimum in applied spot distance between laser spots to obtain higher melting rates.

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Gao, Lei Lei, and Jin Zhong Zhang. "The Tribological Properties of Mg Alloy Produced by ECAE and Laser Melting." Advanced Materials Research 773 (September 2013): 397–401. http://dx.doi.org/10.4028/www.scientific.net/amr.773.397.

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A new processing procedure was applied to an Mg alloy. This procedure involves the equal channel angular extrusion (ECAE) process and laser melting surface treatment. A commercial Mg alloy was first produced by equal channel angular extrusion (ECAE) process. Then the laser melting surfave treatment was carried out after ECAE. The effects of ECAE and laser melting on tribological properties of the alloy were investigated. Experimental results showed that the mechanical properties and tribological properties of the alloy were improved after ECAE. The laser melting surface treatment can further improve the tribological properties of Mg alloy.

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Shishkovsky, I., and V. Saphronov. "Peculiarities of selective laser melting process for permalloy powder." Materials Letters 171 (May 2016): 208–11. http://dx.doi.org/10.1016/j.matlet.2016.02.099.

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Hwang, Taewoo, Sangwook Han, Youngyun Woo, Ilyeong Oh, and Younghoon Moon. "Fabrication of fine wires using direct laser melting process." Procedia Manufacturing 15 (2018): 564–69. http://dx.doi.org/10.1016/j.promfg.2018.07.278.

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Park, Hong-Seok, and Dinh-Son Nguyen. "Study on Flaking Behavior in Selective Laser Melting Process." Procedia CIRP 63 (2017): 569–72. http://dx.doi.org/10.1016/j.procir.2017.03.146.

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Chivel, Y. "Optical In-Process Temperature Monitoring of Selective Laser Melting." Physics Procedia 41 (2013): 904–10. http://dx.doi.org/10.1016/j.phpro.2013.03.165.

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IMAI, Ken, Toshi-Taka IKESHOJI, Yuji SUGITANI, and Hideki KYOGOKU. "Densification of pure copper by selective laser melting process." Mechanical Engineering Journal 7, no. 2 (2020): 19–00272. http://dx.doi.org/10.1299/mej.19-00272.

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Pinomaa, Tatu, Ivan Yashchuk, Matti Lindroos, Tom Andersson, Nikolas Provatas, and Anssi Laukkanen. "Process-Structure-Properties-Performance Modeling for Selective Laser Melting." Metals 9, no. 11 (October 24, 2019): 1138. http://dx.doi.org/10.3390/met9111138.

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Selective laser melting (SLM) is a promising manufacturing technique where the part design, from performance and properties process control and alloying, can be accelerated with integrated computational materials engineering (ICME). This paper demonstrates a process-structure-properties-performance modeling framework for SLM. For powder-bed scale melt pool modeling, we present a diffuse-interface multiphase computational fluid dynamics model which couples Navier–Stokes, Cahn–Hilliard, and heat-transfer equations. A computationally efficient large-scale heat-transfer model is used to describe the temperature evolution in larger volumes. Phase field modeling is used to demonstrate how epitaxial growth of Ti-6-4 can be interrupted with inoculants to obtain an equiaxed polycrystalline structure. These structures are enriched with a synthetic lath martensite substructure, and their micromechanical response are investigated with a crystal plasticity model. The fatigue performance of these structures are analyzed, with spherical porelike defects and high-aspect-ratio cracklike defects incorporated, and a cycle-amplitude fatigue graph is produced to quantify the fatigue behavior of the structures. The simulated fatigue life presents trends consistent with the literature in terms of high cycle and low cycle fatigue, and the role of defects in dominating the respective performance of the produced SLM structures. The proposed ICME workflow emphasizes the possibilities arising from the vast design space exploitable with respect to manufacturing systems, powders, respective alloy chemistries, and microstructures. By digitalizing the whole workflow and enabling a thorough and detailed virtual evaluation of the causal relationships, the promise of product-targeted materials and solutions for metal additive manufacturing becomes closer to practical engineering application.

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Khan, K., and A. De. "Modelling of selective laser melting process with adaptive remeshing." Science and Technology of Welding and Joining 24, no. 5 (February 5, 2019): 391–400. http://dx.doi.org/10.1080/13621718.2019.1575057.

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Bormann, Therese, Ralf Schumacher, Bert Müller, Matthias Mertmann, and Michael de Wild. "Tailoring Selective Laser Melting Process Parameters for NiTi Implants." Journal of Materials Engineering and Performance 21, no. 12 (July 25, 2012): 2519–24. http://dx.doi.org/10.1007/s11665-012-0318-9.

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Paraschiv, Alexandru, Gheorghe Matache, Mihaela Raluca Condruz, Tiberius Florian Frigioescu, and Ion Ionică. "The Influence of Laser Defocusing in Selective Laser Melted IN 625." Materials 14, no. 13 (June 22, 2021): 3447. http://dx.doi.org/10.3390/ma14133447.

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Laser defocusing was investigated to assess the influence on the surface quality, melt pool shape, tensile properties, and densification of selective laser melted (SLMed) IN 625. Negative (−0.5 mm, −0.3 mm), positive (+0.3 mm, +0.5 mm), and 0 mm defocusing distances were used to produce specimens, while the other process parameters remained unchanged. The scanning electron microscopy (SEM) images of the melt pools generated by different defocusing amounts were used to assess the influence on the morphology and melt pool size. The mechanical properties were evaluated by tensile testing, and the bulk density of the parts was measured by Archimedes’ method. It was observed that the melt pool morphology and melting mode are directly related to the defocusing distances. The melting height increases while the melting depth decreases from positive to negative defocusing. The use of negative defocusing distances generates the conduction melting mode of the SLMed IN 625, and the alloy (as-built) has the maximum density and ultimate tensile strength. Conversely, the use of positive distances generates keyhole mode melting accompanied by a decrease of density and mechanical strength due to the increase in porosity and is therefore not suitable for the SLM process.

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Han, Sang-Wook, Won-Jong Ji, and Young-Hoon Moon. "Fabrication of Gear Having Functionally Graded Properties by Direct Laser Melting Process." Advances in Mechanical Engineering 6 (January 1, 2014): 618464. http://dx.doi.org/10.1155/2014/618464.

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Functionally graded properties are characterized by the variation in composition and structure gradually over volume, resulting in corresponding changes in the properties of the material. Direct laser melting (DLM) process is a kind of prototyping process whereby a 3D part is built layerwise by melting the metal powder with laser scanning. DLM can directly build full-density and high-performance complex metal parts from CAD solid model without using any molds and tools. The aim of the study is to demonstrate the possibility to produce functionally graded properties in gear through the direct laser melting of compositionally selected metallic powders. Properties of manufactured parts depend strongly on each single laser-melted track. Therefore, effects of the processing parameters such as scanning speed and laser power on single tracks formation are explored. For the fabrication of gear, building direction and hatch angle have been precisely controlled. Hardness test and EDX analysis were carried out on cross-section of fabricated gear to characterize functionally graded properties. From the analysis, functionally graded properties can be successfully obtained by DLM of selected metallic powders having different compositions.

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Li, Zeng Qiang, Jun Wang, and Qi Wu. "Molecular Dynamics Simulation of the Ablation Process in Ultrashort Pulsed Laser Machining of Polycrystalline Diamond." Advanced Materials Research 500 (April 2012): 351–56. http://dx.doi.org/10.4028/www.scientific.net/amr.500.351.

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The mechanism of ultrashort pulsed laser ablation of polycrystalline diamond (PCD) is investigated using molecular dynamics simulation. The simulation model provides a detailed atomic-level description of the laser energy deposition to PCD specimens and is verified by an experiment using 300 fs laser irradiation of a PCD sample. It is found that grain boundaries play an important role in the laser ablation. Melting starts from the grain boundaries since the atoms in these regions have higher potential energy and are melted more easily than the perfect diamond. Non-homogeneous melting then takes place at these places, and the inner crystal grains melt more easily in liquid surroundings presented by the melting grain boundaries. Moreover, the interplay of the two processes, photomechanical spallation and evaporation, are found to account for material removal in ultrashort pulsed laser ablation of PCD.

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Chen, Zhuoer, Caroline Lee, Sheng Cao, Xuerui Lyu, Xinhua Wu, and Chris Davies. "Process variation in Selective Laser Melting of Ti-6Al-4V alloy." MATEC Web of Conferences 321 (2020): 03024. http://dx.doi.org/10.1051/matecconf/202032103024.

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The present work explores the variation in Ti-6Al-4V part quality introduced by the key process operations of Selective Laser Melting (SLM) process, the recoating, the gas flow, and the laser beam irradiation. Novel specimens and experiments were designed to characterize the differences in surface quality and thermal history as a function of part geometry and location on the build platform. The variation in the roughness of inclined surfaces shows a clear dependency on the laser incidence angle and the influence of gas flow on process by-products. The direction in which the laser beam traverse across the build area with respect to the gas flow direction also affects the surface quality. Thermal profiles were recorded by attaching thermocouples to the surface of the built part with various geometries. The measured temperature profiles show intense local fluctuations due to the rapid movement of the laser beam. The parts also experience a continuous heat treatment throughout the SLM process due to the low effective conductivity of the powder bed and continuous heat input by the laser.

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Huang, Gen Zhe, Zeng Hui Li, and Jian Yin Tang. "Effect of Laser Surface Modification and Tempering Process on Microstructure and Hardness Profiles of Roll Materials." Advanced Materials Research 314-316 (August 2011): 1900–1905. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.1900.

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Laser surface modification, using a continuous wave CO2 crosscurrent laser with generated beam power of 1 kW, was performed on the adamite steel, indefinite chilled cast iron and high speed steel rolls which were applied to the industries. Optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and micro Vickers hardness test were applied to reveal the microstructural details and hardness profiles of the laser treated zone. The results indicate that, laser treated zones of three roll samples consist of melting zone, phase transformation zone and heat affected zone. After laser treatment, the melting zone have low hardness compared to the phase transformation zone, but after tempering at 540°C for 1 hr, the hardness at the melting zone dramatically increases, because of the formation of the fresh martensite from retained austenite. In contrast, the hardness at the phase transformation zone sharply decreases as fresh martensite changed to tempered martensite. There are many small and well distributed FeS and MnS inclusions in the melting zone at the three roll samples.

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Das, Saurabh, and Satya Prakash Kar. "Role of Marangoni Convection in a Repetitive Laser Melting Process." Materials Science Forum 978 (February 2020): 34–39. http://dx.doi.org/10.4028/www.scientific.net/msf.978.34.

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To effectively interpret the fluid flow dynamics in the molten metal pool, a numerical model was established. The moving repetitive Gaussian laser pulse is irradiated in the work piece. The consideration of laser scanning speed makes the transport phenomena complex. The continuity and momentum equations are solved to get the flow velocity of the molten metal in the melt pool. The energy equation is solved to know the temperature field in the work piece. The algebraic equations obtained after discretization of the governing equations by Finite Volume Method (FVM) are then solved by the Tri Diagonal Matrix Method. Enthalpy-porosity technique is used to capture the position of the melt front which determines the shape of the melt pool. Marangoni convection is considered to know its effect on the shape of the melt pool. The surface tension coefficient is taken as both positive and negative value while calculating the Marangoni force. The two possible cases will cause the Marangoni force to distort the flow dynamics in the melt pool . It's dominance over the buoyancy force in controlling the melt pool shape is focused in the present study. Further, the present model will present an insight to the consequences of laser scanning velocity over the melt pool dimensions and shape.

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Craeghs, Tom, Stijn Clijsters, Jean Pierre Kruth, Florian Bechmann, and Marie Christin Ebert. "Detection of Process Failures in Layerwise Laser Melting with Optical Process Monitoring." Physics Procedia 39 (2012): 753–59. http://dx.doi.org/10.1016/j.phpro.2012.10.097.

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38

Duitsch, U., S. Schreck, and M. Rohde. "Modelling of laser induced surface modification of ceramic substrates." Journal de Physique IV 120 (December 2004): 389–95. http://dx.doi.org/10.1051/jp4:2004120044.

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A laser supported process has been developed to modify the electrical and thermal properties of ceramic substrates locally. This process is characterised by a strong thermal interaction between the laser beam and the ceramic surface which leads to localised melting. During the dynamic melting process an additional metallic material is introduced. After the solidification a metal-ceramic composite has been generated with different physical properties compared to the non-modified ceramic. The heat and mass transfer during this dynamic melting and solidification process has been studied experimentally and also numerically in order to identify the dominating process parameters. Simulation tools based on a finite element model have been developed to describe the heat transfer, fluid flow and the phase change during the melting and solidification of the ceramic. The results of the calculation have been validated against experimental results.

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Gebbe, Christian, Max Lutter-Günther, Benjamin Greiff, Johannes Glasschröder, and Gunther Reinhart. "Measurement of the Resource Consumption of a Selective Laser Melting Process." Applied Mechanics and Materials 805 (November 2015): 205–12. http://dx.doi.org/10.4028/www.scientific.net/amm.805.205.

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One important purchasing criterion for end customers is the resource consumption of products, which manufacturers aim to reduce through sustainable product designs and optimization of production processes. In order to quantify the resource consumption, in this study the demand of raw materials and operating materials of the selective laser melting process was quantified according to the methodology developed within the initiative Cooperative Effort on Process Emissions in Manufacturing (CO2PE!). The selective laser melting process was selected due to two reasons. First, the process enables lightweight constructions, which offers the potential to reduce the resource consumption during the product use phase. Second, few studies have been published about this process so far which also measure the demand of compressed air and shielding gas apart from the electric energy demand. It was found that the resource demand for the manufactured 0.5 cm3cuboid part amounted to 3.6 kWh electric energy, 0.81 m3compressed air and 0.31 m3Argon. This corresponds to an energy demand of nearly 1000 kWh/kg, though such key performance indicators alone are not very representative for the selective laser melting process, as described below.

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De Pasquale, G., F. Luceri, and M. Riccio. "Experimental evaluation of selective laser melting process for optimized lattice structures." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 4 (September 27, 2018): 763–75. http://dx.doi.org/10.1177/0954408918803194.

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Lattice structures fabricated with micromelting of metal powders are promising solutions for lightweight applications. Additive manufacturing processes as selective laser melting are largely used to build bulk components, but the influence of laser settings on lattice struts morphology is not jet fully investigated. Previous studies demonstrate the effect of laser speed and layers thickness on the material density and lattice struts dimensions. In this paper, the effects of the laser volume energy density associated with the process setup parameters are analyzed in relation to the dimensional accuracy of lattice struts. The statistical approach based on design of experiments used in this paper allows getting appreciable reduction of the average errors of struts dimensions (from 48% to 16% and from 22% to 7% in horizontal and vertical orientations, respectively).

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Minasyan, Tatevik, Le Liu, Sofiya Aydinyan, Maksim Antonov, and Irina Hussainova. "Selective Laser Melting of Ti/cBN Composite." Key Engineering Materials 799 (April 2019): 257–62. http://dx.doi.org/10.4028/www.scientific.net/kem.799.257.

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Titanium has been evaluated in a broad range of aerospace, biomedical and sports equipment applications due to its unique combination of high mechanical strength, light weight and good biocompatibility. However, Ti implants are often subject to wear in specific areas. Therefore, the improvement of mechanical properties, such as hardness, wear resistance, bearing capability of implants is a key point to broaden the application fields of titanium. Cubic boron nitride (cBN) is a well-known superhard material possessing high chemical stability and biocompatibility. However, cBN suffers from poor machinability and sinterability. Attempts to process boron nitride by laser treatment into intricate shapes are extremely difficult, expensive and time-consuming tasks squeezing its applicability. In this work, manufacturing of Ti/cBN cellular structures and solid parts of high strength and good wear resistance by selective laser melting was performed. In Ti/cBN composite powder, the boron nitride provides the excellent mechanical properties, and titanium promotes the laser absorption improving the process of densification. The parametric study of consolidation process has been performed and the microstructural features along with mechanical properties are examined.

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Geng, Lin, Qing Wu Meng, and Yan Bin Chen. "In-Situ Synthesis of Metal Matrix Composite Coating with Laser Melting-Solidifying Processes." Key Engineering Materials 313 (July 2006): 139–44. http://dx.doi.org/10.4028/www.scientific.net/kem.313.139.

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In order to improve wear resistance of titanium alloy, with pre-placed B4C and NiCrBSi powders on Ti-6Al-4V substrate, a process of laser melting-solidifying metal matrix composite coating was studied. The coating was examined using XRD, SEM and EDS. A good metal matrix composite coating was obtained in a proper laser process. There is a metallurgical interface bonding between the coating and the substrate. During laser melting-solidifying process, high energy of laser melted the pre-placed powders and a part of Ti-6Al-4V substrate, which made Ti extend into a melting pool. A reaction between Ti and B4C took place in the melting pool, which in-situ synthesized TiB2 and TiC reinforcements in the coating. The composite coating mainly consists of γ-Ni matrix, TiB2, TiC and CrB reinforcements. Microstructure of the reinforcements obtained using the laser melting-solidifying is not as same as that of reinforcements obtained using general producing methods. Due to high cooling rate of the melting pool, TiC nucleated primarily and grew up in dendrite morphology from undercooled liquid. Encircling TiC, TiB2 precipitated later and grew up in hexagonal prism morphology. TiC and TiB2 formed an inlaid microstructure.

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Sing, Swee Leong, Wai Yee Yeong, Florencia Edith Wiria, Bee Yen Tay, Ziqiang Zhao, Lin Zhao, Zhiling Tian, and Shoufeng Yang. "Direct selective laser sintering and melting of ceramics: a review." Rapid Prototyping Journal 23, no. 3 (April 18, 2017): 611–23. http://dx.doi.org/10.1108/rpj-11-2015-0178.

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Purpose This paper aims to provide a review on the process of additive manufacturing of ceramic materials, focusing on partial and full melting of ceramic powder by a high-energy laser beam without the use of binders. Design/methodology/approach Selective laser sintering or melting (SLS/SLM) techniques are first introduced, followed by analysis of results from silica (SiO2), zirconia (ZrO2) and ceramic-reinforced metal matrix composites processed by direct laser sintering and melting. Findings At the current state of technology, it is still a challenge to fabricate dense ceramic components directly using SLS/SLM. Critical challenges encountered during direct laser melting of ceramic will be discussed, including deposition of ceramic powder layer, interaction between laser and powder particles, dynamic melting and consolidation mechanism of the process and the presence of residual stresses in ceramics processed via SLS/SLM. Originality/value Despite the challenges, SLS/SLM still has the potential in fabrication of ceramics. Additional research is needed to understand and establish the optimal interaction between the laser beam and ceramic powder bed for full density part fabrication. Looking into the future, other melting-based techniques for ceramic and composites are presented, along with their potential applications.

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Kim, Hyung Giun, Won Rae Kim, Ohyung Kwon, Gyung Bae Bang, Min Ji Ham, Hyung-Ki Park, Kyung-Hwan Jung, Kang Min Kim, Chang-Woo Lee, and Gun-Hee Kim. "Laser beam melting process based on complete-melting energy density for commercially pure titanium." Journal of Manufacturing Processes 45 (September 2019): 455–59. http://dx.doi.org/10.1016/j.jmapro.2019.07.031.

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van Belle, Laurent, Guillaume Vansteenkiste, and Jean Claude Boyer. "Investigation of Residual Stresses Induced during the Selective Laser Melting Process." Key Engineering Materials 554-557 (June 2013): 1828–34. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.1828.

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The selective laser melting process (SLM), belonging to the family of additive manufacturing processes, can create complex geometry parts from a CAD file. Previously, only prototypes were created by SLM, but now this process is used to manufacture quickly and directly functional parts. For example, in the PEP (Pôle Européen de la Plasturgie), this process is used to fabricate tooling parts or injection molds with cooling channels that can’t be obtained by conventional routes. During the process, the laser beam generates violent heating and cooling cycles in the material inducing important thermal gradients in the consolidated part. The cyclic thermal expansions and contractions exceeding the maximum elastic strain of the material induce heterogeneous plastic strains and generate internal stresses the level of which can reaches the yield stress of the material and cracks may appear during the process. This paper deals with the measurement and analysis of residual stresses during the selective laser melting of a simple part in maraging steel. The objective of this study is the analysis of experimental results to validate the numerical model previously presented in [1]. Some authors have investigated the residual stresses produced in SLM parts using different experimental measurement methods such as the incremental hole drilling method in [2], the layer removal method see in [3] and [4] or the non-destructive method, by neutron diffraction in [5]. A new method is proposed to evaluate the residual stresses induced during the SLM process, a rosette is fixed on the bottom face of the support. The residual stresses in the created part are calculated from strain and temperature variations when the fused layer is consolidating during the cooling between two layers. Process parameters like the powder thickness or the time cooling between successive layers are studied in this paper. [1] L. Van Belle, G. Vansteenkiste, J.C. Boyer, Comparisons of numerical modeling of the selective laser melting, Key Engineering Materials Vols. 504-506 (2012) pp 1067-1072 [2] C. Casavola, S.L. Campanelli, C. Pappalettere, Experimental analysis of residual stresses in the selective laser melting process, Proceedings of the XIth International Congress and Exposition, June 2-5, 2008 Orlando, Florida USA [3] M. Shiomi, K. Osakada, K. Nakamura, T. Yamashita, F. Abe, Residual stress within metallic model made by selective laser melting process, CIRP Annals - Manufacturing Technology, Vol. 53, No. 1. (2004), pp. 195-198 [4] T. Furumoto, T. Ueda, M.S. Abdul Aziz, A. Hosokawa and R. Tanaka, Study on reduction of residual stress induced during rapid tooling process, influence of heating conditions on residual stress, Key Engineering Materials Vols. 447-448 (2010) pp 785-789 [5] M. Zaeh, G. Branner, Investigation on residual stresses and deformation in selective laser melting, Production Engineering, Volume 4, Number 1 (2010)

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Khmyrov, Roman S., Cyrill E. Protasov, and Andrey V. Gusarov. "Influence of the conditions of selective laser melting on evaporation." MATEC Web of Conferences 224 (2018): 01060. http://dx.doi.org/10.1051/matecconf/201822401060.

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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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L. Hao, L. Hao, and S. Dadbakhsh S. Dadbakhsh. "Materials and Process Aspects of Selective Laser Melting of Metals and Metal Matrix Composites:A Review(Invited Paper)." Chinese Journal of Lasers 36, no. 12 (2009): 3192–203. http://dx.doi.org/10.3788/cjl20093612.3192.

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Zhang, Dongqi, Jie Yu, Hui Li, Xin Zhou, Changhui Song, Chen Zhang, Shengnan Shen, Linqing Liu, and Chengyuan Dai. "Investigation of Laser Polishing of Four Selective Laser Melting Alloy Samples." Applied Sciences 10, no. 3 (January 21, 2020): 760. http://dx.doi.org/10.3390/app10030760.

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Selective laser melting (SLM) is a layer by layer process of melting and solidifying of metal powders. The surface quality of the previous layer directly affects the uniformity of the next layer. If the surface roughness value of the previous layer is large, there is the possibility of not being able to complete the layering process such that the entire process has to be abandoned. At least, it may result in long term durability problem and the inhomogeneity, may even make the processed structure not be able to be predicted. In the present study, the ability of a fiber laser to in-situ polish the rough surfaces of four typical additive-manufactured alloys, namely, Ti6Al4V, AlSi10Mg, 316L and IN718 was demonstrated. The results revealed that the surface roughness of the as-received alloys could be reduced to about 3 μm through the application of the laser-polishing process, and the initial surfaces had roughness values of 8.80–16.64 μm. Meanwhile, for a given energy density, a higher laser power produced a laser-polishing effect that was often more obvious, with the surface roughness decreasing with an increase in the laser power. Further, the polishing strategy will be optimized by simulation in our following study.

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Rohde, M., O. Baldus, D. Dimitrova, and S. Schreck. "Numerical Simulation of Laser Induced Modification Processes of Ceramic Substrates." Materials Science Forum 492-493 (August 2005): 465–70. http://dx.doi.org/10.4028/www.scientific.net/msf.492-493.465.

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Laser supported processes can be used to modify the electrical and thermal properties of ceramic substrates locally. These processes are characterised by a strong thermal interaction between the laser beam and the ceramic surface which leads to localised melting. During the dynamic melting process an additive material is injected into the melt pool in order to modify the physical properties. The heat and mass transfer during this dynamic melting and solidification process has been studied numerically in order to identify the dominant process parameters. Simulation tools based on a finite volume method have been developed to describe the heat transfer, fluid flow and the phase change during the melting and solidification of the ceramic. The results of the calculation have been validated against experimental results.

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Sukumar, Siladitya, and Satya Prakash Kar. "Thermal Modeling of Transport Phenomena for a Pulsed Laser Melting Process." Materials Science Forum 978 (February 2020): 114–20. http://dx.doi.org/10.4028/www.scientific.net/msf.978.114.

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Single pulsed laser melting in a cylindrical titanium alloy work piece is studied numerically using an axisymmetric model. Finite volume method and Tri-Diagonal Matrix Algorithm (TDMA) are used for discretization of the energy equation and solving the resulting algebraic equation respectively in order to obtain temperature distribution inside the computational domain. Heat losses from the irradiated surface takes place through convection and radiation and other surfaces are kept insulated. A volumetric and Gaussian laser is irradiated on the work piece. Validation of the present model with the existing literature is done first and the results agree very well. Then, the detailed transport phenomena during the laser melting process is studied using the model. The enthalpy porosity technique is used track the melt pool shape and size. The role of natural convection and Marangoni convection in controlling the shape of melt pool is discussed. Maximum temperature results at domain centre and it then decreases exponentially along the axial and radial direction of the work piece because of Gaussian nature of the pulse. The numerical results obtained can provide the direction to develop models for all type of laser applications used in the industry.

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Journal articles on the topic 'Melting process on the laser'

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