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http://dx.doi.org/10.5781/JWJ.2017.35.1.34

A Comparative Study of Weldable Current Range on AC and MFDC Resistance Spot Welding for 440 MPa Grade Steel Sheet  

Ji, Changwook (Advanced Manufacturing Process R &d Group, KITECH)
Park, Chansu (School of Materials Science and Engineering, Pusan National University)
Kim, Chiho (School of Materials Science and Engineering, Pusan National University)
Cho, Yongjoon (Materials Manufacturing Engineering R&D Team, Hyundai Motor Company)
Oh, Dongjin (Department of Naval Architecture and Ocean Engineering, Pusan National University)
Kim, Myung-Hyun (Department of Naval Architecture and Ocean Engineering, Pusan National University)
Kim, Yang-Do (School of Materials Science and Engineering, Pusan National University)
Park, Yeong-Do (Department of Advanced Materials Engineering, Dong-Eui University)
Publication Information
Journal of Welding and Joining / v.35, no.1, 2017 , pp. 34-42 More about this Journal
Abstract
This paper presents a comparative study of the AC and MFDC resistance spot welding process with consideration of sheet thickness. The previous studies have confirmed that there is difference in the optimum welding current and expulsion current with AC and MFDC. The aim of this study was revealing the effect of sheet thickness on weldable current range and expulsion behavior for AC and MFDC welding processes. The optimum welding current of AC was lower (1.6 kA) than MFDC welding process in 0.8 mm sheet thickness. Early nugget growth being caused by the peak current of AC developed weld interface deformation, which resulted in suppressing the growth of corona bond and occurrence of low current expulsion. The resistance spot welding for thicker sheet (1.4 mm) required lower current of 0.6 kA for the expulsion on the MFDC welding process. The growth of contact diameter (size of corona bond) and button diameter was linear up to the expulsion current with MFDC welding process. Therefore, more attention is required when the AC and MFDC resistance spot welding process is applied for different thickness of steel sheet combination for automotive application.
Keywords
Expulsion; AC; MFDC; Weldable current range; Thickness; Weld growth;
Citations & Related Records
Times Cited By KSCI : 5  (Citation Analysis)
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