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6 "Chang-Woo Lee"
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Effect of post heat treatment on fatigue properties of EBM 3D-printed Ti-6Al-4V alloy
Young-Sin Choi, Ji-Hoon Jang, Gun-Hee Kim, Chang-Woo Lee, Hwi-Jun Kim, Dong-Geun Lee
J Korean Powder Metall Inst. 2018;25(4):340-345.   Published online August 1, 2018
DOI: https://doi.org/10.4150/KPMI.2018.25.4.340
  • 107 View
  • 2 Download
  • 4 Citations
AbstractAbstract PDF

Additive manufacturing by electron beam melting is an affordable process for fabricating near net shaped parts of titanium and its alloys. 3D additive-manufactured parts have various kinds of voids, lack of fusion, etc., and they may affect crack initiation and propagation. Post process is necessary to eliminate or minimize these defects. Hot isostatic pressing (HIP) is the main method, which is expensive. The objective of this paper is to achieve an optimum and simple post heat treatment process without the HIP process. Various post heat treatments are conducted for the 3Dprinted Ti-6Al-4V specimen below and above the beta transus temperature (996°C). The as-fabricated EBM Ti-6Al-4V alloy has an α‘-martensite structure and transforms into the α+β duplex phase during the post heat treatment. The fatigue strength of the as-fabricated specimen is 400 MPa. The post heat treatment at 1000°C/30 min/AC increases the fatigue strength to 420 MPa. By post heat treatment, the interior pore size and the pore volume fraction are reduced and this can increase the fatigue limit.

Citations

Citations to this article as recorded by  
  • Effect of Line Energy Conditions on Mechanical and Fatigue Properties of Ti6Al4V Fabricated by Electron Beam Additive Manufacturing
    Youngsin Choi, Hwi-Jun Kim, Gun-Hee Kim, Chang-Woo Lee, Dong-Geun Lee
    Metals.2021; 11(6): 878.     CrossRef
  • Mechanical and Physical Characteristics Analysis of Radius Trauma Plate by EBM Additive Manufacturing
    Kwun-Mook Lim, Sung-Jun Park
    Journal of the Korean Society of Manufacturing Technology Engineers.2020; 29(2): 147.     CrossRef
  • Effect of Heat Treatments on Fatigue Properties of Ti-6Al-4V Alloy Fabricated by EBM Additive Manufacturing
    Dong-Geun Lee, Youngsin Choi, P. Villechaise, B. Appolaire, P. Castany, M. Dehmas, C. Delaunay, J. Delfosse, A. Denquin, E. Gautier, L. Germain, N. Gey, T. Gloriant, J.-Y. Hascoët, S. Hémery, Y. Millet, D. Monceau, F. Pettinari-Sturmel, M. Piellard, F. Pr
    MATEC Web of Conferences.2020; 321: 03027.     CrossRef
  • Correlation between surface tension and fatigue properties of Ti-6Al-4V alloy fabricated by EBM additive manufacturing
    Youngsin Choi, Dong-Geun Lee
    Applied Surface Science.2019; 481: 741.     CrossRef
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A study about sculpture characteristic of SKD61 tool steel fabricated by selective laser melting(SLM) process
Jaecheol Yun, Jungho Choe, Ki-Bong Kim, Sangsun Yang, Dong-Yeol Yang, Yong-Jin Kim, Chang-Woo Lee, Chang-Woo Lee
J Korean Powder Metall Inst. 2018;25(2):137-143.   Published online April 1, 2018
DOI: https://doi.org/10.4150/KPMI.2018.25.2.137
  • 200 View
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  • 1 Citations
AbstractAbstract PDF

In this study, two types of SKD61 tool-steel samples are built by a selective laser melting (SLM) process using the different laser scan speeds. The characteristics of two kinds of SKD61 tool-steel powders used in the SLM process are evaluated. Commercial SKD61 tool-steel power has a flowability of 16.68 sec/50 g and its Hausner ratio is calculated to be 1.25 by apparent and tapped density. Also, the fabricated SKD61 tool steel powder fabricated by a gas atomization process has a flowability of 21.3 sec/50 g and its Hausner ratio is calculated to be 1.18. Therefore, we confirmed that the two powders used in this study have excellent flowability. Samples are fabricated to measure mechanical properties. The highest densities of the SKD61 tool-steel samples, fabricated under the same conditions, are 7.734 g/cm3 (using commercial SKD61 powder) and 7.652 g/cm3 (using fabricated SKD61 powder), measured with Archimedes method. Hardness is measured by Rockwell hardness testing equipment 5 times and the highest hardnesses of the samples are 54.56 HRC (commercial powder) and 52.62 HRC (fabricated powder). Also, the measured tensile strengths are approximately 1,721 MPa (commercial SKD61 powder) and 1,552 MPa (fabricated SKD61 powder), respectively.

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  • Microstructural effects on the tensile and fracture behavior of selective laser melted H13 tool steel under varying conditions
    Jungsub Lee, Jungho Choe, Junhyeok Park, Ji-Hun Yu, Sangshik Kim, Im Doo Jung, Hyokyung Sung
    Materials Characterization.2019; 155: 109817.     CrossRef
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Mechanical Property Improvement of the H13 Tool Steel Sculptures Built by Metal 3D Printing Process via Optimum Conditions
Jaecheol Yun, Jungho Choe, Haengna Lee, Ki-Bong Kim, Sangsun Yang, Dong-Yeol Yang, Yong-Jin Kim, Chang-Woo Lee, Ji-Hun Yu
J Korean Powder Metall Inst. 2016;24(3):195-201.   Published online June 1, 2016
DOI: https://doi.org/10.4150/KPMI.2017.24.3.195
  • 238 View
  • 4 Download
  • 7 Citations
AbstractAbstract PDF

In this study, H13 tool steel sculptures are built by a metal 3D printing process at various laser scan speeds. The properties of commercial H13 tool steel powders are confirmed for the metal 3D printing process used: powder bed fusion (PBF), which is a selective laser melting (SLM) process. Commercial H13 powder has an excellent flowability of 16.68 s/50 g with a Hausner ratio of 1.25 and a density of 7.68 g/cm3. The sculptures are built with dimensions of 10 × 10 × 10 mm3 in size using commercial H13 tool steel powder. The density measured by the Archimedes method is 7.64 g/cm3, similar to the powder density of 7.68 g/cm3. The hardness is measured by Rockwell hardness equipment 5 times to obtain a mean value of 54.28 HRC. The optimum process conditions in order to build the sculptures are a laser power of 90 W, a layer thickness of 25 μm, an overlap of 30%, and a laser scan speed of 200 mm/s.

Citations

Citations to this article as recorded by  
  • Spheroidization of Enamel Powders by Radio Frequency Plasma Treatment and Application to Additive Manufacturing
    Ki-Bong Kim, Dong-Yeol Yang, Yong-Jin Kim, Jungho Choe, Ji-Na Kwak, Woo-Hyung Jung
    Journal of Korean Powder Metallurgy Institute.2020; 27(5): 388.     CrossRef
  • Microstructural effects on the tensile and fracture behavior of selective laser melted H13 tool steel under varying conditions
    Jungsub Lee, Jungho Choe, Junhyeok Park, Ji-Hun Yu, Sangshik Kim, Im Doo Jung, Hyokyung Sung
    Materials Characterization.2019; 155: 109817.     CrossRef
  • Nano-mechanical Behavior of H13 Tool Steel Fabricated by a Selective Laser Melting Method
    Van Luong Nguyen, Eun-ah Kim, Jaecheol Yun, Jungho Choe, Dong-yeol Yang, Hak-sung Lee, Chang-woo Lee, Ji-Hun Yu
    Metallurgical and Materials Transactions A.2019; 50(2): 523.     CrossRef
  • Correlation between Microstructure and Mechanical Properties of the Additive Manufactured H13 Tool Steel
    Woojin An, Junhyeok Park, Jungsub Lee, Jungho Choe, Im Doo Jung, Ji-Hun Yu, Sangshik Kim, Hyokyung Sung
    Korean Journal of Materials Research.2018; 28(11): 663.     CrossRef
  • Evaluation of Strain-Rate Sensitivity of Selective Laser Melted H13 Tool Steel Using Nanoindentation Tests
    Van Luong Nguyen, Eun-ah Kim, Seok-Rok Lee, Jaecheol Yun, Jungho Choe, Dong-yeol Yang, Hak-sung Lee, Chang-woo Lee, Ji-Hun Yu
    Metals.2018; 8(8): 589.     CrossRef
  • Comparison of Nano-Mechanical Behavior between Selective Laser Melted SKD61 and H13 Tool Steels
    Jaecheol Yun, Van Luong Nguyen, Jungho Choe, Dong-Yeol Yang, Hak-Sung Lee, Sangsun Yang, Ji-Hun Yu
    Metals.2018; 8(12): 1032.     CrossRef
  • A study about sculpture characteristic of SKD61 tool steel fabricated by selective laser melting(SLM) process
    Jaecheol Yun, Jungho Choe, Ki-Bong Kim, Sangsun Yang, Dong-Yeol Yang, Yong-Jin Kim, Chang-Woo Lee, Chang-Woo Lee
    Journal of Korean Powder Metallurgy Institute.2018; 25(2): 137.     CrossRef
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The Influence of a Single Melt Pool Morphology on Densification Behavior of Three-Dimensional Structure Fabricated by Additive Manufacturing
Jungho Choe, Jaecheol Yun, Dong-Yeol Yang, Sangsun Yang, Ji-Hun Yu, Chang-Woo Lee, Yong-Jin Kim
J Korean Powder Metall Inst. 2016;24(3):187-194.   Published online June 1, 2016
DOI: https://doi.org/10.4150/KPMI.2017.24.3.187
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  • 5 Citations
AbstractAbstract PDF

Selective laser melting (SLM) can produce a layer of a metal powder and then fabricate a three-dimensional structure by a layer-by-layer method. Each layer consists of several lines of molten metal. Laser parameters and thermal properties of the materials affect the geometric characteristics of the melt pool such as its height, depth, and width. The geometrical characteristics of the melt pool are determined herein by optical microscopy and three-dimensional bulk structures are fabricated to investigate the relationship between them. Powders of the commercially available Fe-based tool steel AISI H13 and Ni-based superalloy Inconel 738LC are used to investigate the effect of material properties. Only the scan speed is controlled to change the laser parameters. The laser power and hatch space are maintained throughout the study. Laser of a higher energy density is seen to melt a wider and deeper range of powder and substrate; however, it does not correspond with the most highly densified three-dimensional structure. H13 shows the highest density at a laser scan speed of 200 mm/s whereas Inconel 738LC shows the highest density at 600 mm/s.

Citations

Citations to this article as recorded by  
  • Microstructural effects on the tensile and fracture behavior of selective laser melted H13 tool steel under varying conditions
    Jungsub Lee, Jungho Choe, Junhyeok Park, Ji-Hun Yu, Sangshik Kim, Im Doo Jung, Hyokyung Sung
    Materials Characterization.2019; 155: 109817.     CrossRef
  • Correlation between Microstructure and Mechanical Properties of the Additive Manufactured H13 Tool Steel
    Woojin An, Junhyeok Park, Jungsub Lee, Jungho Choe, Im Doo Jung, Ji-Hun Yu, Sangshik Kim, Hyokyung Sung
    Korean Journal of Materials Research.2018; 28(11): 663.     CrossRef
  • Effect of Porosity on Mechanical Anisotropy of 316L Austenitic Stainless Steel Additively Manufactured by Selective Laser Melting
    Jeong Min Park, Jin Myoung Jeon, Jung Gi Kim, Yujin Seong, Sun Hong Park, Hyoung Seop Kim
    Journal of Korean Powder Metallurgy Institute.2018; 25(6): 475.     CrossRef
  • Evaluation of the Accuracy of Dental Prostheses manufactured by Metal 3D Printer
    Junho Hwang, Yun-Ho Kim, Hyun-Deok Kim, Kyu-Bok Lee
    Journal of Welding and Joining.2018; 36(5): 70.     CrossRef
  • A study about sculpture characteristic of SKD61 tool steel fabricated by selective laser melting(SLM) process
    Jaecheol Yun, Jungho Choe, Ki-Bong Kim, Sangsun Yang, Dong-Yeol Yang, Yong-Jin Kim, Chang-Woo Lee, Chang-Woo Lee
    Journal of Korean Powder Metallurgy Institute.2018; 25(2): 137.     CrossRef
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Synthesis of Tungsten Heavy alloy Nanocomposite Powder by Ultrasonic-milling Process
Seung-Chul Lee, Chang-Woo Lee, Sung-Soo Jung, Berm-Ha Cha, Jai-Sung Lee
J Korean Powder Metall Inst. 2007;14(2):101-107.
DOI: https://doi.org/10.4150/KPMI.2007.14.2.101
  • 145 View
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  • 2 Citations
AbstractAbstract PDF
Ultrasonic-milling of metal oxide nanopowders for the preparation of tungsten heavy alloys was investigated. Milling time was selected as a major process variable. XRD results of metal oxide nanopowders ultrasonic-milled for 50 h and 100 h showed that agglomerate size reduced with increasing milling time and there was no evidence of contamination or change of composition by impurities. It was found that nanocomposite powders reduced at 800°C in a hydrogen atmosphere showed a chemical composition of 93.1W-4.9Ni-2.0Fe from EDS analysis. Hardness of sintered part using 50 h and 100 h powder samples was 399 Hv and 463 Hv, respectively, which is higher than the that of commercial products (330-340 Hv).

Citations

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  • Grinding behavior of WO3, NiO, Fe2O3 by ultrasonic milling parameters control and preparation of nanocomposite powder
    Keunhyuk Ryu, Kun-Jae Lee
    Advanced Powder Technology.2020; 31(9): 3867.     CrossRef
  • Investigation on Size Distribution of Tungsten-based Alloy Particles with Solvent Viscosity During Ultrasonic Ball Milling Process
    KeunHyuk Ryu, HyeongSub So, JiSeok Yun, InHo Kim, Kun-Jae Lee
    Journal of Korean Powder Metallurgy Institute.2019; 26(3): 201.     CrossRef
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Synthesis of γ-Fe2O3 Nanoparticles by Low-pressure Ultrasonic Spraying
Chang-Woo Lee, Soon-Gil Kim, Yong-Ho Choa, Jai-Sung Lee
J Korean Powder Metall Inst. 2007;14(1):19-25.
DOI: https://doi.org/10.4150/KPMI.2007.14.1.019
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AbstractAbstract PDF
This study was focused on the optimization of low-pressure ultrasonic spraying process for synthesis of pure gamma-Fe_2O_3 nanoparticles. As process variables, pressure in the reactor, precursor concentration, and reaction temperature were changed in order to control the chemical and microstructural properties of iron oxide nanoparticles including crystal phase, mean particle size and particle size distribution. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies revealed that pure gamma-Fe_2O_3 nanoparticles with narrow particle size distribution of 5-15 nm were successfully synthesized from iron pentacarbonyl (Fe(CO)_5) in hexane under 30 mbar with precursor concentrations of 0.1M and 0.2M, at temperatures over 800°C. Also magnetic properties, coercivity (H_c) and saturation magnetization (M_s) were reported in terms of the microstructure of particles based on the results from vibration sampling magnetometer (VSM).

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