| Weld Quality Evaluation Method for the Resistance Spot Welds using X-ray Transmission Inspection |
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Jong-Dae Lee*,**, So-Jeong Lee*, Jung-Hwan Bang*, Gil-Sang Yoon*,***, Mok-Soon Kim**, Jun-Ki Kim*,*** |
1Advanced Welding & Joining R&BD Group, KITECH, Incheon 406-130, Korea
2School of Materials Science and Engineering, Inha University, Incheon 402-751, Korea
3Electronic Packaging Engineering, University of Science & Technology, Incheon 406-130, Korea |
Correspondence:
Jun-Ki Kim,
Email: jkim@kitech.re.kr
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| Abstract |
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For the resistance spot welds of CR1180 and GA1180 TRIP steels, the weld quality evaluation method using the digitalized X-ray transmission imaging apparatus was investigated in comparison with the cross-sectional examination method. In the case of the resistance spot welding of CR1180, three circular regions, such as WZ(white zone), GZ(grey zone) and DZ(dark zone), appeared on X-ray image and they corresponded to the diameters of indentation mark, nugget and corona bond, respectively. The variation of X-ray transmission thickness due to the thickness variation of the weld seemed to be mainly responsible for the formation of those contrasts. The X-ray image contrast formed from the variation of transmission thickness at the outer border line of DZ could also enable the inspections of the notch shape, nonuniformity of the welding pressure and spatter from its sharpness, concentricity and the normal straight line, respectively. The X-ray image of the resistance spot weld of galvannealed GA1180 TRIP steel was very similar to that of CR1180 TRIP steel except the crown shaped outer border line of DZ which was considered to be due to the melting behavior of zinc having the boiling temperature even lower than the melting temperature of steel. |
| Key Words:
Ultra high strength steel(UHSS), Resistance spot welding, X-ray transmission inspection, Welding nugget, Weld inspection, Weld quality |
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