| 摘要 |
<p>A galvanized steel sheet is provided which has a tensile strength of not less than 80 kgf/mm<2> and a yield ratio of not more than 60%, and which is applicable to members of an automobile body, particularly those requiring strength. By appropriately controlling the amounts of components, such as C, Mn, Nb, Ti and B, the structure of the steel sheet is formed into a dual-phase structure having a second phase structure. The steel sheet is recrystallization-annealed, galvanized while it is maintained at a temperature range near 500 DEG C, and then is cooled. By controlling the rate of cooling the steel sheet, the second phase structure generated is prevented from hardening more than necessary. A galvanized high-strength steel sheet is obtained which has a low yield ratio and excellent stretch-flanging properties.</p> |
