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Mechanical properties and microstructures of resistance spot welded DP980 steel joints using pulsed current pattern |
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| Authors: | C Sawanishi T Ogura K Taniguchi R Ikeda K Oi K Yasuda |
| Affiliation: | 1. Graduate student, Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan (Present address: JFE Steel Corporation);2. Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan;3. JFE Steel Corporation, 1 Kawasaki-cho, Chuo-ku, Chiba 260-0835, Japan |
| Abstract: | Dual phase 980 MPa grade (DP980) steel sheets were resistance spot welded using a pulsed current, and the effects of the pulsed current on the strength properties of the joints were investigated. The pulsed current improved the mechanical properties of the joints in cross tensile tests. In situ observations during tear tests revealed that the ductility of the nugget was improved and that the propagation of cracks into the nugget was inhibited when the pulsed current was used. Microstructural observations and electron probe microanalysis (EPMA) of the nugget showed that the segregation of phosphorus at the nugget was reduced in the joint welded using the pulsed current, suggesting that the pulsed current improved the ductility of the nugget by altering their microstructures. |
| Keywords: | Resistance spot welding DP980 Pulsed current pattern Cross tensile test Tear test In situ observation Microstructure |