1997 Volume 83 Issue 2 Pages 145-150
There is an increasing demand for steel sheet that should be completely free from oiling and degreasing during the forming operation in order to improve working environment and hence global environment ; In order to achieve this we studied a lubricated galvanized steel sheet, which has a thin organic film consist of base resin, lubricant and silica for the anti-corrosive agent on the chromated upper layer.
A lubricated galvanized steel sheet requires not only good lubricity but also good resistance to mechanical damage that causes deterioration of surface appearance. From the point of the improvement of resistance against mechanical damage, an organic film has high level of mechanical strength to reduce powdering by sliding, and has adequate softness that allows the film to follow to the press deformation well. The tensile strength and elongation of various polyurethane resin films were measured. On the basis of the test results, it was concluded that blended aromatic resin base polyurethane and aliphatic one was bridged by hardener has good mechanical properties to provide excellent surface appearance.
Polyethylene lubricant in the film had good coefficient of friction at wide range of temperature, as compared with other solid lubricant. From the point of the balance of corrosion resistance and surface appearance after forming, 1015wt% silica content in the film had better performance.
