過熱水蒸気中におけるNi基合金での割れ感受性、粒界酸化、皮膜酸化物に及ぼす酸化力の影響
Effect of oxygen potential on oxide film, intergranular oxidation and cracking susceptibility on nickel base alloy in superheated steam
著者:
熊谷 大介 Daisuke KUMAGAI 阿部 博志 Hiroshi ABE 渡邉 豊 Yutaka WATANABE
発刊日:
公開日:
cracking susceptibilityintergranular oxidationNi base alloyoxide filmOxygen potential
概要
In this study, we investigate the effect of oxygen potential on oxide film, intergranular oxidation and cracking susceptibility on nickel base alloy in hydrogenated superheated steam at 400℃. Intergranular cracking occurred at oxygen potential of LOGPO2=-26.32(Ni/NiO equilibrium). In contrast, no cracking occurred at oxygen potential of LOGPO2=-24.09 and LOGPO2=-27.04(near the cracked condition). This result shows that oxygen potential range for cracking susceptibility seemed to be narrow in hydrogenated superheated steam. Raman spectroscopic analyses have identified that Cr2O3 exists on oxide film of all specimens not only cracked specimens. TEM analyses have identified Cr depleted area exist ahead of crack tip. The observation supports that internal oxidation along the grain boundary cause the intergranular cracking.
