| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve deep drawability even in the case of electric furnace steelmaking which unavoidably causes a contamination with tramp elements, by limiting the contents of elements to values in the prescribed ranges, respectively. SOLUTION: The elements, which are specially noteworthy, are as follows: C is an important element to obtain an excellent r-value of >=2.3 under proper Cu and Ni contents and Mn/S and its content is regulated to <=0.0050wt.%: N is incorporated by 0.0040-0.0090wt.% to allow proper amounts of TiN to exist: Ti has a function of precipitating and fixing solid-solution C and N to prevent deterioration in deep drawability and also contributing to the improvement of r-value, so its content is regulated to 0.014-0.10wt.%: Cu and Ni are tramp elements difficult to remove at the time of reclamation of iron scrap and produce an adverse effect on deep drawability but the existence of them in proper amounts is effective in refining crystalline grains of hot rolled plate, so the contents of Cu and Ni are regulated to <=0.96wt.% and <=0.88%, respectively, and 0.0015<=Cu/64+Ni/59<=0.0150 i s satisfied. Further, superior deep drawability of >=2.5 r-value can be obtained by regulating the value of Mn/S to <=7.0.</p> |
