1Cr-1Mo-1/4V 鋳鋼の長時間クリープ破断性質に影響する金属学的因子

概要

論文の詳細を見る
Creep rupture data extending 80000h duration have been obtained from nine castings of Cr-Mo-V steam turbine steel. The data of the nine castings showed a wide range of rupture time at higher stresses and lower temperatures, and also a wide range of rupture ductility at lower stresses and longer rupture times. The rupture time variation was found to arise from the differences in fine distribution of V_4C_3 and high matrix dislocation density. The V_4C_3 distributions and the dislocation densities of the nine castings became similar one another as stress was reduced and rupture time consequently increased, which corresponded to a narrow range of rupture time at lower stresses and higher temperatures. All of the castings showed the rupture ductility falling at longer times, which was associated with a change from transgranular to intergranular fracture due to cavitation. Therefore the rupture ductility behaviour at longer times depended mainly on a susceptibility to cavitation, and the susceptibility was closely connected with segregation of impurities (P, S, Sn, Sb, Cu and As) to grain boundaries. Total amount of the impurities segregated to grain boundaries had a clear correlation with the reduction of area at rupture.
社団法人日本鉄鋼協会の論文
1989-06-01