高温クリープ負荷環境における窒素添加ステンレス鋼SUS316の粒界割れ機構の解明

抄録

In this study, an intermittent creep test was applied to the continuous observation of the change of the micro texture of SUS316LN and the initiation of intergranular cracking. It was found that the accumulation of dislocations along specific grain boundaries which were perpendicular to the direction of the applied uniaxial stress and the difference of the magnitude of plastic deformation between two nearby grains were the dominant factors of intergranular cracking. The large difference in the Schmid Factor between the nearby grains was attributed to the accumulation, and thus, the place where intergranular cracking started to occur. In addition, comparison experiments between SUS316L and SUS316LN were carried out to verify the improvement effect of material strength due to nitrogen doping. The relationship between nitrogen doping and Stacking Fault Energy (SFE) was briefly discussed.