Corrosion Performance of Zn-Ni Alloy Plated Sheet Steel in Automotive Body Panels

The corrosion resistance of Zn-Ni alloy electroplated sheet steel (SZ) against perforation and cosmetic corrosion was investigated in cyclic corrosion tests and service corrosion environment.

Perforation resistance was evaluated in two cyclic corrosion tests using unpainted and 5 μm electrocoated panels without scribe. SZ 20 g/m² showed equivalent or superior corrosion resistance to that of Galvannealed sheet steel (GA) 60 g/m² .This excellent protection ability of SZ Has validated by the field performance in OKINAWA.

Cosmetic corrosion resistance of fully painted panels with scribe were estimated in Modified Volvo Scab Test. SZ and the other pre-coated steels had distinctive corrosion performance in comparison with cold rolled steel (CR). This result correlated well with that of monitor cars in OKINAWA and WAKAYAMA.