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Effect of Post-Heat Treatment on the Impact Toughness and Crack Propagation Mechanism of AISI D2 Tool Steel Manufactured by Direct Energy Deposition

Park Jun-Hyung, Kim Kyu-Sik, Koo Yong-Mo, Kim Jin-Young, Kim Min-Chul, Lee Kee-Ahn

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

119--122

EN

This study investigated the effect of heat treatment on the microstructure and impact toughness property of AISI D2 manufactured with direct energy deposition (DED) and compared the results with conventional wrought material. The fracture crack propagation behavior was examined in connection with microstructures through fracture surface analysis. AISI D2 manufactured with DED had a eutectic structure that turned into a net-type carbide after heat treatment, and Cr-rich needle-type secondary carbide was observed. Impact toughness of DED AISI D2 measured 2.0 J/cm2 in the as-built sample and 1.1 J/cm2 in the heat-treated sample. Compared to a wrought heat-treated AISI D2, DED AISI D2 had relatively low impact toughness. DED AISI D2 and wrought material had different crack propagation mechanisms. In DED AISI D2, the eutectic structure and net-type carbide boundary were identified as the major microstructural factor decreasing impact toughness.

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Direct Energy Deposition of Mo Powder Prepared by Electrode Induction Melting Gas Atomization

Roh Goo-Won, Park Eun-Soo, Moon Jaeyun, Lee Hojun, Byun Jongmin

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 3

795--798

EN

Molybdenum (Mo) is used to form a barrier layer for metal wiring in displays or semiconductor devices. Recently, researches have been continuously attempted to fabricate Mo sputtering targets through additive manufacturing. In this study, spherical Mo powders with an average particle size of about 37 um were manufactured by electrode induction melting gas atomization. Subsequently, Mo layer with a thickness of 0.25 mm was formed by direct energy deposition in which the scan speed was set as a variable. According to the change of the scan speed, pores or cracks were found in the Mo deposition layer. Mo layer deposited with scan speed of 600 mm/min has the hardness value of 324 Hv with a porosity of approximately 2%. We demonstrated that Mo layers with higher relative density and hardness can be formed with less effort through direct energy deposition compared to the conventional powder metallurgy.

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Deposition Characteristics of High-Thermal-Conductivity Steel in the Direct Energy Deposition Process and its Hardness Properties at High Temperatures

Son Jong-Youn, Shin Gwang-Yong, Lee Ki-Yong, Yoon Hi-Seak, Shim Do-Sik

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 4

1365--1369

EN

Direct energy deposition (DED) is a three-dimensional (3D) deposition technique that uses metallic powder; it is a multi-bead, multi-layered deposition technique. This study investigates the dependence of the defects of the 3D deposition and the process parameters of the DED technique as well as deposition characteristics and the hardness properties of the deposited material. In this study, high-thermal-conductivity steel (HTCS-150) was deposited onto a JIS SKD61 substrate. In single bead deposition experiments, the height and width of the single bead became bigger with increasing the laser power. The powder feeding rate affected only the height, which increased as the powder feeding rate rose. The scanning speed inversely affected the height, unlike the powder feeding rate. The multi-layered deposition was characterized by pores, a lack of fusion, pores formed by evaporated gas, and pores formed by non-molten metal inside the deposited material. The porosity was quantitatively measured in cross-sectionsof the depositions, revealing that the lack of fusion tended to increase as the laser power decreased; however, the powder feeding rate and overlap width increased. The pores formed by evaporated gas and non-molten metal tended to increase with rising the laser power and powder feeding rate; however, the overlap width decreased. Finally, measurement of the hardness of the deposited material at 25°C, 300°C, and 600°C revealed that it had a higher hardness than the conventional annealed SKD61.

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Poprawa porowatości przedmiotów z Inconelu 625 wytwarzanych metodą druku 3D

Jemielniak Krzysztof

Mechanik

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2019

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R. 92, nr 8-9

514

PL

Druk 3D metodą bezpośredniej depozycji energii – DED (direct energy deposition) – wiąże się ze stosowaniem dużej ilości energii cieplnej, która generuje gradient temperatury w wytwarzanym wyrobie. Zwykle prowadzi to do niespodziewanej anizotropii i osłabienia materiału przez resztkową porowatość. Te problemy można rozwiązać dzięki dodatkowej procedurze przetapiania, zapewniającej kontrolowaną orientację kryształów i redukcję porowatości.