| 摘要 |
The present invention relates to a box annealing heat treatment method of steel sheets for automobiles with a purpose to provide a box annealing heat treatment method for manufacturing cold-rolled steel plates for automobiles with an excellent quality by deriving box annealing heat treatment conditions of cold-rolled steels with mechanical properties suitable to be used for automobiles. The present invention provides a box annealing het treatment method of steel plates for automobiles, comprising; a heating step for heat steel plates containing in weight % carbon (C) : 0.06~0.10%, silicon (Si) : less than 0.5% , manganese (Mn) : 1.6~2.0%, phosphor (P) : less than 0.04% , sulfur (S) : less than 0.005% , aluminum (Al) : 0.01~0.05%, niobium (Nb) : 0.01~0.05%, nitrogen (N) : less than 0.006% in addition to a balance of iron (Fe) and unavoidable impurities; and a heating maintenance step at a heating maintenance temperature of 625~655°C for an annealing time of 10±1 hours; and a cooling step to cool down the heating maintained steel sheets. [Reference numerals] (AA) Temperature (°C); (BB) Target temperature |
