| 摘要 |
PURPOSE:To manufacture one-side galvenized steel plate of good processability for auomobile steel plate, etc., by using a rimmed steel by providing a one-side hot galvanizing apparatus between an overaging treatment device for steel strip and a secondary cooling chamber with non-oxidative atmosphere. CONSTITUTION:After recrystallization annealing by heating, low-carbon steel strip is subjected to a primary overaging treatment at the overaging chamber 18 and then intruced into the one-side galvanizing chamber 20 with non-oxidative atmosphere to continuously coat the one side alone of the steel strip with fused zinc. Then, it is introduced into the secondary cooling chamber 21 with non-oxidative atmosphere, and then subjected to temper rolling and coiled. Or, it is further sent to a heating device before the galvanizing chamber 20 or to an alloying treatment device after the galvanizing chamber for respective treatments. In this case, overaging treatment is made at 350 to 400 deg.C and the temperature of strip is raised to a galvanizable temperature of 430 to 500 deg.C in a short time enough not to cause the separation of carbon (within about 5 min) and shortly thereafter galvanization is made. Thus, galvanized steel plate of excellent processability can be obtained. |
