連続焼鈍による低炭素 Al キルド冷延鋼板製造における熱延低温巻取りの検討

概要

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Metallurgical factors realizing low temperature coiling of hot-rolled bands for producing deep-drawable continuous-annealed Al-killed sheet steels have been investigated in order to improve yield and productivity. The following proposal is given : the control of chemical composition such as i) C≦0.02%, ii) Mn≦0.15%, and iii) Al≧0.05%, and the choice of iv) low slab reheating temperature below 1150℃. The conditions i) and ii) contribute to the coarsening of cementite particles in hot-rolled bands and to the reduced amount of Mn-C complex during annealing, while the condition iii) contributes to the promotion of AlN precipitation in hot-rolled bands. These are considered to play a significant role in ameliorating r^^--value of the final products. Furthermore the condition iv) not only has an effect of improving formability, but also contributes to the prevention of hot-shortness caused by S. The effective mechanisms are discussed concerning the influence of C and Mn contents on the cementite coarsening in hot-rolled bands. On the basis of the knowledge obtained by the laboratory investigation, a mill test was carried out and it was confirmed that the proposal ensures a high and uniform r^^--value through the whole length of a coil employing the low temperature coiling.
社団法人日本鉄鋼協会の論文
1990-09-01