| 摘要 |
PURPOSE:To produce galvanized steel plate for use as deep drawing by a method wherein cold rolled steel plate is heated to a temperature higher than recrystallization temperature and held there, is subjected to a primary cooling and process by overaging treatment, is galvanized, cooled, and is chemically treated. CONSTITUTION:In the radiator pipe type heating zone 5, a cold rolled steel plate is heated at 700 deg.C which is higher than recrystallization temperature, then is heated uniformly in the uniform heating zone 6 for 10 seconds. The steel is subject to the primary cooling in the primary cooling zone 7-500 deg.C at a cooling rate of 3- 500 deg.C/s, then undergoes overaging treatment at 600-450 deg.C for 30 seconds to 3 minutes in the primary overaging zone 8. The plate is soon galvanized in the pit furnace 9 and is cooled from 450 deg.C-350 deg.C in the jet type cooling zone 10. Next, the plate undergoes the secondary overaging process at 400-250 deg.C for less than 3 minutes in the secondary overaging zone 11. Thereafter, the plate is cooled in the secondary and third cooling zone 12-40 deg.C or below which is a refinable temperature, undergoes refining rolling using refiner roller 14, passes through chemical processor 16, drier 17, and is wound on the take-up reel 21. |
