| 摘要 |
PURPOSE:To improve the workability, chemical conversion treatment property, material quality, etc. of plating layers by subjecting a steel plate carried out with zinc hot dipping to a primary heat treatment in a line to annihilate spangles then passing the steel plate through a heating furnace thereby forming alloyed layers. CONSTITUTION:In a continuous zinc hot dipping line, zinc plating is carried out on a steel plate by using a plating bath 1 contg. 0.08-0.20% Al in molten zinc. The steel plate is heat treated by holding the same for 10-40sec at 460-600 deg.C in a primary heating furnace 2 in the line, whereby the spangles on the surface layers of the plating are annihilated. In succession, the steel plate is passed through a secondary heating furnace 3 installed in the line, where the plate is heated for 1-3min at 400-440 deg.C to form alloyed layers of Fe-Zn on the surfaces of the steel plate. By such method, the galvanealed steel plate having excellent chemical conversion treatment property and the workability of the plating layers is produced stably without any limitation for the compsns. of steel materials. |
