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Number of results: 8
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Abstract

In this study, we investigated the effect of cladding on structural carbon steel (S45C) using 5%Cr-1.5%Mo-Fe powder (SKD61), which is expected to show economically efficient production of die-casting parts. The process conditions were performed under argon atmosphere using a diode laser source with specialized wavelength of 900-1070 nm, and the output conditions were 3, 4, and 5 kW, respectively. After the cladding was completed, the surface coating layer’s shape and the microstructure were analyzed. The hardness test was carried out with Micro Vickers hardness tester under 500 gram-force along the normal line at the interval of 0.2 mm from the surface to core direction on the cross-sectional area. In addition, polarization curve test of the surface coating layer was performed to investigate the corrosion resistance characteristics.
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Authors and Affiliations

Cheol-Woo Kim
1
ORCID: ORCID
Hyo-Sang Yoo
1
ORCID: ORCID

  1. Suncheon Ppuri Technology Support Center, Korea Institute of Industrial Technology, 34, Haeryongsandan 2-ro, Haeryong-myeon, Suncheon-si, Jeollanam-do, 58022, Korea
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Abstract

Laser cladding is a method that can be applied to repair the crack and break on the mold and die surfaces, as well as generate new attributes on the surface to improve toughness, hardness, and corrosion resistance. It is used to extend the life of the mold. It also has the advantages of superior bonding strength and precision coating on a local area compared with the conventional thermal spraying technology. In this study, we investigated the effect of cladding on low carbon alloy steel using 18%Cr-2.5%Ni-Fe powder (Rockit404), which showed high hardness on the die surface. The process conditions were performed in an argon atmosphere using a diode laser source specialized for 900-1070 nm, and the output conditions were 5, 6, and 10 kW, respectively. After the cladding was completed, the surface coating layer’s shape, the hardness according to the cross-section’s thickness, and the microstructure were analyzed.
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Bibliography

[1] M . U. Saleem, Sustainability 10, 1761 (2018).
[2] J. Tang, J. Egypro 5, 708 (2011).
[3] N. Ali, J. Heliyon 6, e05050 (2020).
[4] Y. Li, J. Jmrt 9, 3856 (2020).
[5] P. Kattire, J. Jmapro. 20, 492 (2015).
[6] Z. Zhang, J. Jallcom. 790, 703 (2019).
[7] X. Xu, J. Jallcom. 715, 362 (2017).
[8] G . Telasang, J. Surfcoat. 258, 1108 (2014).
[9] J.H. Lee, J. KWJS 18, 27 (2000).
[10] Z. Liu, J. Surfcoat. 384, 125325 (2020).
[11] E .R. Mahmoud, J. Matpr. 39, 1029 (2020).
[12] Y.T. Yoo, J. Korean Society 22, 17 (2005).

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Authors and Affiliations

Cheol-Woo Kim
1
ORCID: ORCID
Hyo-Sang Yoo
1
ORCID: ORCID
Jae-Yeol Jeon
1
Kyun-Taek Cho
1
Se-Weon Choi
1
ORCID: ORCID

  1. Smart Mobility Materials and Components R&D Group, Korea Institute of Industrial Technology, 1110-9 Ory ong-dong, Buk-gu, Gwan gju, Republic of Korea
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Abstract

In this study, the extrusion characteristics of Al-2Zn-1Cu-0.5Mg-0.5RE alloys at 450, 500, and 550℃ were investigated for the high formability of aluminum alloys. The melt was maintained at 720℃ for 20 minutes, then poured into the mold at 200℃ and hot-extruded with a 12 mm thickness bar at a ratio of 38:1. The average grain size was 175.5, 650.1, and 325.9 μm as the extrusion temperature increased to 450, 500 and 550℃, although the change of the phase fraction was not significant as the extrusion temperature increased. Cube texture increased with the increase of extrusion temperature to 450, 500 and 550℃. As the extrusion temperature increased, the electrical conductivity increased by 47.546, 47.592 and 47.725%IACS, and the tensile strength decreased to 92.6, 87.5, 81.4 MPa. Therefore, the extrusion temperature of Al extrusion specimen was investigated to study microstructure and mechanical properties.

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Authors and Affiliations

Yong-Ho Kim
ORCID: ORCID
Hyo-Sang Yoo
ORCID: ORCID
Kyu-Seok Lee
Sung-Ho Lee
Hyeon-Taek Son
ORCID: ORCID
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Abstract

In this study, we investigated the effect of Fe addition (0, 0.25, 0.50 and 0.75 wt.%) on the microstructure, mechanical properties and electrical conductivity of as-cast and as-extruded Al-RE alloys. As the Fe element increased by 0 and 0.75wt.%, the phase fraction increased to 5.05, 5.76, 7.14 and 7.38 %. The increased intermetallic compound increased the driving force for recrystallization and grain refinement. The electrical conductivity of Al-1.0 wt.%RE alloy with Fe addition decreased to 60.29, 60.15, 59.58 and 59.13 %IACS. With an increase in the Fe content from 0 to 0.75 wt.% the ultimate tensile strength (UTS) of the alloy increased from 74.3 to 77.5 MPa. As the mechanical properties increase compared to the reduction of the electrical conductivity due to Fe element addition, it is considered to be suitable for fields requiring high electrical conductivity and strength.

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Authors and Affiliations

Hyo-Sang Yoo
ORCID: ORCID
Yong-Ho Kim
ORCID: ORCID
Hyeon-Taek Son
ORCID: ORCID
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Abstract

This study investigated the effect of cladding on tool steel (SKD61) by using 5%Cr-1.5%Mo-Fe powder (SKD61), which is expected to be economically effective when used to manufacture and mend die-casting parts. The cladding conditions were as follows: the distance between the coaxial powder supply head and the substrate surface was 20 mm, and Ar was used as the supply gas. The laser outputs applied in the cladding procedure were 3, 4, and 5 kW. The microstructure of the heat-affected zone in the processed specimens was analyzed, and the macrostructure and morphology of the substrate material were studied. Specimen hardness measurements were performed at intervals of 0.1 mm from the substrate surface to the core. As the laser output increased from 3 to 4 and 5 kW, the dilution rate increased from 10.6% to 11.8 and 13.2%. It was confirmed that the fraction of carbides increased as the laser output increased from 3 kW to 5 kW.
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Authors and Affiliations

Cheol-Woo Kim
1
ORCID: ORCID
Hyo-Sang Yoo
1
ORCID: ORCID
Sung-Kil Hong
2
ORCID: ORCID

  1. Korea Institute of Industrial Technology, Suncheon, Korea
  2. Chonnam National University, School of Materials Science and Engineering, 61186, Korea
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Abstract

This research describes effects of Si addition on microstructure and mechanical properties of the Al-Cr based alloys prepared manufactured using gas atomization and SPS (Spark Plasma Sintering) processes. The Al-Cr-Si bulks with high Cr and Si content were produced successfully using SPS sintering process without crack and obtained fully dense specimens close to nearly 100% T. D. (Theoretical Density). Microstructure of the as-atomized Al-Cr-Si alloys with high contents of Cr and Si was composed multi-phases with hard and thermally stable such as Al13Cr4Si4, AlCrSi, Al8Cr5 and Cr3Si intermetallic compounds. The average hardness values were 703 Hv for S5, 698 Hv for S10 and 824 Hv for S20 alloy. Enhancement of hardness value was resulted from the formation of the multi-intermetallic compound with hard and thermally stable and fine microstructure by the addition of high Cr and Si using rapid solidification and SPS process.

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Authors and Affiliations

Yong-Ho Kim
ORCID: ORCID
Ik-Hyun Oh
ORCID: ORCID
Hyo-Sang Yoo
ORCID: ORCID
Hyun-Kuk Park
ORCID: ORCID
Jung-Han Lee
Hyeon-Taek Son
ORCID: ORCID
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Abstract

In this study, the effects of heat-treatment conditions of Fe powder compacts on densification, microstructure, strength and magnetic properties were investigated. The prepared Fe powder was compressed in a mold of diameter 20 mm at a pressure of 800 MPa for 30 sec. This Fe powder compact was heat-treated under different atmospheres (air and 90% Ar + 10% H2 and heat-treatment temperatures (300 and 700℃). The Fe powder compacts heat-treated in an Ar+H2 mixed gas atmosphere showed a denser microstructure and higher density than the Fe powder compacts heat-treated in an air atmosphere. Oxygen content in the heat-treatment conditions played a significant role in the improvement of the densification and magnetic properties.
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Authors and Affiliations

Hyo-Sang Yoo
1
ORCID: ORCID
Yong-Ho Kim
1
ORCID: ORCID
Cheol-Woo Kim
1
ORCID: ORCID
Hyeon-Taek Son
1
ORCID: ORCID

  1. Korea Institute of Industrial Technology, Automotive Materials & Components R&D Group, 1110-9 Oryong-dong, Buk-gu, Gwangju 61012, Republic of Korea
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Abstract

This study investigated the improvement in the electrical conductivity and mechanical properties obtained by adjusting the amount of the Sr addition to the Al-Zn-Mg-Mn alloy. The addition of Sr formed an intermetallic compounds, and the volume fraction of the intermetallic compounds increased with increasing Sr content. As the amount of Sr added increased from 0 to 1.0 wt%, the electrical conductivity of the extruded alloy decreased to 48.9, 45.2 and 42.5% IACS. As the addition amount of Sr increased, the average grain size of the rolled alloy decreased to 55.5, 53.1 and 42.3 μm. And, the ultimate tensile strength increased to 195, 212 and 216 MPa.
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Authors and Affiliations

Hyo-Sang Yoo
1 2
ORCID: ORCID
Yong-Ho Kim
1
ORCID: ORCID
Byoung-Kwon Lee
1
ORCID: ORCID
Eun-Chan Ko
1
ORCID: ORCID
Sang-Chan Lee
2
ORCID: ORCID
Seong-Hee Lee
2
ORCID: ORCID
Hyeon-Taek Son
1
ORCID: ORCID

  1. Korea Institute of Industrial Technology, Automotive Materials & Components R&D Group, 1110-9 Oryong-dong, Buk-gu, Gwangju 61012, Republic of Korea
  2. Mokpo National University, Jeollanamdo, Republic of Korea

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