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Kang D.S.,Chonbuk National University | Woo K.D.,Chonbuk National University | Lee T.,Chonbuk National University | Lee H.C.,Chonbuk National University | And 2 more authors.
Materials Research Innovations | Year: 2015

The influence of yttrium addition on high-temperature performance of stress rupture property and oxidation resistance in Inconel 713C has been investigated. High-temperature stress rupture property and oxidation resistance property of Inconel 713C were dramatically improved with increasing yttrium addition content up to 0•02%yttrium, then decreased in excess of yttrium. Especially, the carbide morphology changed to discrete blocky shapes by causing improved high-temperature properties. Intermetallic compounds by excess yttrium addition made a poor stress rupture life. The high-temperature oxidation resistance of 0•02 wt-% yttrium added Inconel 713C improved more than no added yttrium Inconel 713C. © W. S. Maney & Son Ltd 2015.


Lee H.C.,Chonbuk National University | Wo K.D.,Chonbuk National University | Kang D.S.,Chonbuk National University | Lee T.,Chonbuk National University | And 2 more authors.
Materials Research Innovations | Year: 2015

The as-cast Co-Cr-Mo alloy (ASTM F75) has been widely used as biomaterial in orthopaedic implant because of its excellent mechanical properties, good corrosion resistance and biocompatibility. However, some defects such as porosity and pinhole in an as-cast make some problems for application. Therefore in this study, the cobalt-aluminate (CoAl2O4) used as an inoculant during coating plays to refine the grain size and to reduce the porosity and pinhole content in an as-cast. Therefore, the effect of an inoculant addition on defect content, microstructure and mechanical properties of as-cast Co-Cr-Mo alloy has been investigated. The mechanical properties of the Co-Cr-Mo alloy were improved by addition of an inoculant. © W. S. Maney & Son Ltd 2015.


Kang D.S.,Chonbuk National University | Woo K.D.,Chonbuk National University | Kim D.G.,Chonbuk National University | Kim S.M.,Chonbuk National University | And 3 more authors.
Advanced Materials Research | Year: 2013

Turbochargers of automobilehave been widely used in commercial vehicles by diesel engine. Nowadays, turbochargeris being tried to use passenger car by gasoline engine such as deluxe and compact car. Therefore, fabrication method and conditions of turbine wheel which is core parts ofautomobile turbochargers,arereviewed by Lost wax method. To fabrication of turbine wheel using Inconel 713C alloy, vacuum induction melting (VIM) with alumina (Al2O3) crucible was used. Inas- cast Inconel 713C alloy, the strength at the elevated temperature is not satisfied to commercial standard. Therefore, heat treatment was introduced in Inconel 713C alloy to increase strength. The strength at the elevated temperature was increased by aging treatment. © (2013) Trans Tech Publications, Switzerland.


Kang D.S.,Chonbuk National University | Woo K.D.,Chonbuk National University | Kim D.G.,Chonbuk National University | Lee T.,Chonbuk National University | And 2 more authors.
71st World Foundry Congress: Advanced Sustainable Foundry, WFC 2014 | Year: 2014

Ni-Cr-Mo based superalloy has been applied in turbochargers components of automotive and several vehicles engine. Recently turbochargers application steeply expand not only diesel engine cars but gasoline engine cars because of low emission gas, lo fuel consumption and engine downsizing. This IN 713C alloys shows good performance in an automotive engine components such as turbine wheel, waste gate valve due to their excellent strength and creep property of γ' precipitates (L12 of FCC structure) and MC (M23C6 type) carbides. The high temperature properties will be improved by increasing density of γ' precipitate [Ni3(Al, Ti), L12 of FCC structure] through proper heat treatment. The primary γ' phase is precipitated at solidification as large size and second γ' phase is precipitated following aging treatment as fine size at high temperature. The MC carbide (metal carbide) exists as MC and M6C along grain boundary formed by casting and M23C6 precipitated by aging treatment. Furthermore, the rare earth elements are positively considered with causing excellent high temperature mechanical property of superalloy. Among them, the yttrium element (Y) is an important role in high temperature mechanical property of superalloy. In this study, the high temperature strength of IN 713C was increased by addition of yttrium up to 0.36wt% as well as elongation. The Y2O3 particles formed by reaction between yttrium and oxygen in molten metal might be contributed to excellent high temperature strength by distribution along grain boundary.

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