Spotting is a phosphating defect of electrogalvanized (EG) steel strongly influenced by the phosphating parameters. Under given phosphating bath conditions, however, the intrinsic EG material's properties exert a strong influence on the white spotting susceptibility. An investigation revealed that co-deposited lead and nickel had opposing influences on the white spotting susceptibility, apparently due to their effects on the reactivity of the plated zinc. In a series of laboratory and industrial plating trials, a low-nickel EG product was produced and was confirmed to have improved phosphatability.
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