| 摘要 |
PURPOSE:To perform molten Zn plating of easy alloying, by adjusting molten Zn bath temp. in the vicinity of plating surface according to P, Si contents in a steel sheet and Al content in molten Zn bath, at molten Zn plating of the steel sheet of general steel, and steel to which P, Si are added, premising the alloying after plating. CONSTITUTION:The steel sheet S is passed through molten Zn plating bath contg. 0.12-0.14% Al, adhered molten Zn quantity is squeezed to a suitable quantity by a roll 5 and a squeezing gas nozzle 6, then said sheet is heated by a galvanic furnace 7 for alloying the plated Zn with the steel sheet. In this case, shielding cylinders 8a, 8b having heaters 9, coolers 10 are provided before and after a deflector roll 4. Temp. of molten Zn is measured by thermocouples 11, said temp. is adjusted to a temp. T satisfying a formula at 440-500 deg.C according to P, Si contents, Al content in the plating bath in narrow range in both shielding cylinders. Thereby, plated steel sheet having high alloying rate can be manufactured. |
