Characteristics of dewy Spread Lightly Tin-Coated Steel for Welded Cans

This study concerns development of material for welded cans made of 0.7-0.8g/m2 dewy spread lightly tin coated steel. It has been well known that more than 0.1g/m2 of free tin results in good weldability. Low-tin steel, however readily forms alloys during baking, resulting in degradation in both weldability and corrosion resistance. These properties were improved by: 1) covering the steel surface with a continuous dense layer of Fe (Ni)-Sn alloy; 2) distributing the tin like islands a few micrometer in diameter to provide a surface coverage of 10-50%; 3) forming a uniform chromate film, consisting of 4-10mg/m2 chromium as CrEC and 6-15mg/m2 chromium as oxide. The material, thus produced exhibits out-standing results weldability and corrosion resistance and it could replace tin plate as a material for welded cans.