Effects of Cyclic Test Variables on the Corrosion Resistance of Automotive Sheet Steels

The rate of corrosion of sheet steel adjacent to the crevice area of a hem flange is strongly influenced by the individual parameters of a cyclic exposure schedule. Conditions which promote drying of the hem pocket accelerate metal loss. These include increased temperature, longer forced drying time, and minimizing proximity to moisture reservoirs in the equipment. While increased frequency of the cyclic saline dip/drain/force dry sequence does not change the average rate of metal loss, it does produce more rapid growth of individual pits.