Corrosion Behavior of MIG Brazed and MIG Welded Joints of Automotive DP600-GI Steel Sheet
Galvanized dual-phase steel sheets are extensively used by the auto industry for their corrosion resistance property. Welding by the metal inert gas (MIG) process causes degradation of the steel in the vicinity of the joint due to excessive zinc evaporation. In order to minimize Zn loss, the MIG brazing process has been tried out in lap joint configuration over a heat input range of 136–204 J mm−1. The amount of zinc loss, intermetallic formation and corrosion properties in the joint area has been evaluated for both MIG brazing and MIG welding. Corrosion rate of 21 mm year−1 has been reduced to 2 mm year−1 by adopting MIGB in place MIGW. Impedance study has shown that the corrosion mechanism in base metal, MIG brazed and MIG welded joints is dominated by charge transfer, diffusion and mixed mode control processes, respectively.
Keywordsgalvanized DP steel MIG brazing MIG welding potentiodynamic study salt spray test electrochemical impedance study
The work was supported by the Council of Scientific and Industrial Research (CSIR), New Delhi, India. The authors would like to thank Mrs. Nitu Rani of Tata Steel R&D for her valuable assistance in the salt spray corrosion test.
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