| 摘要 |
PURPOSE:To surface treated steel plate of improved lubricating characteristics under severe working conditions such as of drawing, punching. etc. of steel plates comprising providing the composite films composed of a crystalline phosphorus compound layer containing Fe of an under layer and amorphous phosphorus compound layer of an upper layer on the surfaces of the steel plate. CONSTITUTION:Phosphoric acid, phosphate or phosphorus compound is coated on the surfaces of a steel plate, which is then heated to 200 deg.C or higher in a non-oxidative atmosphere which hardly contains moisture, whereby the intended surface treated steel plate is made. In this treating process, the rate that the amorphous film being the upper layer occupies in the total film thickness is larger and that of the under layer is smaller as the heating temperature is lower. When the steel plate is heated to high temperatures (500 to 800 deg.C), the reaction with Fe progresses and the under layer grows. And the underlayer of the resultant composite films is formed to thicknesses of 0.5 to 0.1mum, particularly 0.01 to 0.1mum and the upper layer to thicknesses of 0.05 to 1.0mum, respectively. |
