Atmospheric exposure tests have been carried out at 8 selected sites in Japan on steel panels electroplated with various Ni-Cr coating systems. Accelerated corrosion tests were also made on the same type of the deposits to establish the correlation between the atmospheric corrosion tests and the accelerated ones. The corrosion of Ni-Cr type platings was so influenced by the environmental factors that the corrosion loss was found to be different from each other in exposure sites and test seasons. The correlation was observed between the corrosion loss of the platings and the mean values in 3 months of temperature, relative humidity, precipitation and amount of sulfur dioxide which were measured as the environmental corrosive factors, and the relative humidity among them had the most pronounced effect on the corrosion. The salt spray test and CASS test were found to be unsuitable as an accelerated corrosion test, because both test results had no relation to the atmospheric corrosion of Ni-Cr type platings. On the other hand, a fairly good correlation was found between the atmospheric corrosion and SO2 corrosion test or the combination cyclic test in which SO2 concentration, temperature, humidity, and water spraying were controlled by the proposed cycle.
