低N領域におけるTi処理効果
1984 年 2 巻 1 号 p. 33-39
詳細
1984 年 2 巻 1 号 p. 33-39
Ti treatment has been developed to apply to heavy plate and line pipe steel.
Ti treatment disperses fine TiN particles in steel, and improves welded H.A.Z. toughness of the steel.
Recently, by the advance in steel making technology, it becomes easy to make low Nitrogen content steel. Accordingly, we investigated the effect of Ti treatment on low Nitrogen content steel. The results were as follows;
(1) On synthetic H.A.Z. toughness test, the toughness was improved remarkably through the finegrained H.A.Z. structure by the effect of Ti treatment.
(2) Consequently, on low N and low Ti content steel, the synthetic H.A.Z. toughness was inferior, because the amount of dispersed TiN was few and there was few effect to make H.A.Z. structure fine-grained.
(3) On synthetic H.A.Z. toughness test, the optimum range is about 0.015-0.020%Ti and 60-80 ppm N content range.
(4) On actual multi-pass welding, multi-thremal cycle itself has the effect of making H.A.Z. structure fine-grained, therefore, the fine-grained structure effect of Ti treatment didn't appear clearly. Low N and low Ti content steel had good H.A.Z. toughness, too.
