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Vol.46, No.8, 495 ~ 506, 2008
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| Title |
| Resistance Spot Weldability of Surface Roughness Textured Galvannealed Steel Sheets |
| 박상순 Sang Soon Park , 김기홍 Ki Hong Kim , 강남현 Nam Hyun Kang , 김영석 Young Seok Kim , 임영목 Young Mok Rhym , 최영민 Yung Min Choi , 박영도 Yeong Do Park |
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| Abstract |
| With the high proportion of zinc coated steels in body-in-white assembly, newly developed surface roughness textured galvannealed steel sheets have been introduced. In this study, zinc coated and surface roughness textured steel sheets were welded by resistance spot welding to investigate its weldability including electrode wear test. Based on the results of tensile-shear test, nugget diameter changes, and electrode tip growth test, it was clear that both surface roughness textured steels (GA-T and GA-E) showed good weldability. Also, there was no large difference in weldability and electrode wear behavior between GA-T and GA-E steels which have different surface roughness morphology. An analysis of electrode degradation showed Fe and Zn penetration through the electrode tip surface at 2400 welds reached 55~60 μm and 75~80 μm, respectively. Therefore, there is no significant effect of surface roughness morphology on spot weldability of surface roughness textured galvannealed steel sheets. However, slight difference in thickness of alloying layers existing on electrode tip was found between GA-T and GA-E steels. |
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| Key Words |
| resistance spot welding, surface roughness, galvannealed steel, Lobe curve, dynamic resistance, penetration, electrode tip alloying |
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