80kg/mm^2 級高張力鋼板の衝撃性能の改善

概要

論文の詳細を見る
High tensile strength steel plate of 80kg/mm^2 grade which contains rather higher Al content in order to make a small amount of boron effective, shows in some cases very poor impact property in transverse direction. Authors made systematic investigations about manufacturing processes from slab rolling to plate rolling as well as chemical compositions such as nitrogen and titanium. It was found that poor impact energy in transverse direction was caused by AlN which precipitated concentratedly at the austenite grain boundaries during slow cooling after slab rolling and afterwards on the stage of plate rolling modified its distribution to line in row to longitudinal direction. The ways to get the improved impact energy in transverse direction were also found as follows : 1. lowering the finishing temperature in slab rolling below 1100℃. 2. increasing the cooling rate after slab rolling above 15℃/min. 3. raising the heating temperature before plate rolling above 1100℃ so that AlN re-dissolves. 4. decreasing the nitrogen content as low as possible. 5. a small amount of Ti addition. The methods 1-3 are intended to modify the distribution of AlN and the ones 4-5 to decrease the amount of it.
社団法人日本鉄鋼協会の論文
1980-02-01