2024 Volume 42 Issue 1 Pages 40-49
The purpose of this study is to clarify the effect of Ti addition on the solidification cracking susceptibility of carbon steel. Using two-phase peritectic solidification model considering MnS and TiC crystallization, the effect of Ti addition on the BTR of carbon steel was theoretically investigated. The results suggest that Ti addition improves the BTR of carbon steel. On the other hand, when Ti was added in excess, the BTR of carbon steel deteriorated due to an increase in the amount of Ti segregation, thus suggesting the existence of an appropriate amount of Ti depending on the amount of C. The appropriate amount of Ti could be uniformly arranged by the Ti/C ratio regardless of the amount of C. The Ti/C = 5 to 8 was shown to be the appropriate range for Ti addition. In order to experimentally confirm the effect of Ti addition shown by the theoretical study, Ti-variable materials were prepared for 0.05 and 0.15%C steels. EPMA analysis of the weld metal microstructure showed the formation of TiC in the Ti-added material. The BTR of the Ti-variant material was evaluated by the Trans-Varestraint tests, and the BTR improvement effect of Ti addition was confirmed for the 0.15%C steel, and the appropriate Ti addition range was Ti/C=6.3. In this study, the effect of BTR improvement by Ti addition and the appropriate range of Ti addition were proposed based on the theoretical model for BTR of carbon steel. In addition, the effect of Ti addition was experimentally confirmed by evaluating the BTR.
