抄録
The inclusion which stimulated the ferrite nucleation was directly classified through the in-situ observation experiments in the HAZ of the Ti-killed steel weld. The chemical composition of the selected inclusion was analyzed and the nucleation potential was discussed. The potential for the ferrite nucleation is ranked as follows: grain boundary, Ti-X and MnS in order. Furthermore, the existence of effective and ineffective MnS for nucleation was made clear and the difference was estimated.
