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A galvannealed steel sheet (GA) with a Ni-base inorganic lubricant film has been developed to meet the needs of the automotive industry, especially for improved press formability. This paper describes the results of tests performed to evaluate formability, spot weldability, phosphatability, paintability and corrosion resistance of the GA with the Ni-base lubricant film. The coefficient of friction as measured by flat sliding test decreases with increasing Ni content in the lubricant film. The spot weldability evaluated by electrode tip life test is slightly improved after the application of the lubricant film. Phosphatability, paintability and corrosion resistance of the GA with the lubricant film are equivalent to those of GA without the lubricant film.

Weldable vibration damping steel sheet consists of two skin steel sheets and viscoelastic resin film that contains filler metal powder to get electric conductivity. In this study, it is investigated the effect of filler powder (type; size and content) on weld defects. The defects are observed when the resin layer is thick comparing with the powder diameter or the content of metal powder is insufficient. The defect with bare skin sheets which is spherical hole is caused by joule overheating. Another defect is observed when Zn-Fe coated skin sheets are used. According to the observation of welding current and voltage wave forms. It is formed by an arc electric discharge between metal powder and skin sheet, which is caused by cutting off current paths due to the evaporation of Zn-Fe coated layer. Based on these results, it is determined the suitable filler powder to produce VDSS with good weldability.