Process for preparing surface-treated steel strips adapted for electric resistance welding.

摘要

Surface-treated steel strips suitable for electric resistance welding are prepared by forming a first layer of iron-nickel alloy on a steel strip, said first layer having a weight ratio of Ni/(Fe + Ni) in the range between 0.02 and 0.50 and a thickness of 10 to 5,000 angstroms, forming a second layer of tine or iron-tin-nickel alloy on said first layer by tin plating to a coating weight of 0.1 to 1 g/m2 of tin and optionally, causing the tin to reflow, and forming athird layer on said second layer by effecting an electrolytic chromate treatment, said third layer consisting essentially of metallic chromium and hydrated chromium oxide in a total amount of 5 to 20 mg/m2 calculated as elemental chromium. More preferably, the electrolytic chromate treatment is controlled such that at least 2 mg/m2 of metallic chromium is present in the third layer.