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Vol.57, No.3, 193 ~ 202, 2019
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| Title |
| Study of the Corrosion Behaviour, Liquid Metal Embrittlement and Resistance Spot Weldability of Galvannealed Hot Stamping Steel |
| 황연정 Yeonjung Hwang , 이창욱 Chang Wook Lee , 신가영 Ga-young Shin , 유지홍 Ji Hong Yoo , 최민수 Minsu Choi |
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| Abstract |
| The hot stamping process is beneficial for fabricating high strength automotive parts without spring back. To suppress high temperature oxidation and decarburization, it is necessary to coat the hot stamping steel. In the present work, the performance of galvannealed coated (GA) hot stamped steel was evaluated. During cyclic corrosion tests, the steel substrate began to corrode after the heat treated galvannealed coating fully corroded, because a Zn alloyed coating provides cathodic protection. In order to be applied to the automotive body-in-white, GA coated hot stamped steel must overcome drawbacks such as liquid metal embrittlement (LME) due to the low melting temperature of the Zn, and low or limited weldability due to the thick surface ZnO layer. The results of this study showed that an increase in the α-Fe(Zn) phase fraction of the coating was an effective way to prevent LME. In addition, the resistance spot weldability of GA hot stamped steel can be improved by removing the thick Zn oxide layer by sand blasting.
(Received October 17, 2018; Accepted January 18, 2019) |
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| Key Words |
| hot stamping, galvannealed coating, cathodic protection, liquid metal embrittlement, resistance spot welding |
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