Creep degradation assessment for creep-strength-enhanced ferritic steels by positron annihilation spectroscopy

用正电子寿命谱研究了高蠕变强度铁素体钢的蠕变退化。正电子平均寿命随蠕变时间的变化可分为三个区域，即初始阶段下降、中间阶段逐渐下降和断裂前大幅下降。这些区域几乎分别对应于瞬态、稳态和加速区域。此外，平均正电子寿命的增加，在初始蠕变时间从蠕变试验前对应于在钢中的蠕变试验过程中的沉淀物的形成。给出了用正电子平均寿命估算蠕变寿命的方法。

Creep degradation of creep-strength-enhanced ferritic steels was studied by positron lifetime spectroscopy. Creep time dependence of mean positron lifetime consists of three regions that are decrease in initial stage, gradual decrease in middle stage, and large decrease before rupture. These regions almost correspond to transient, steady-state, and accelerating regions, respectively. Furthermore, increase of the mean positron lifetime in the initial creep time from that before creep test corresponds to formation of precipitates during the creep test in the steels. Creep life assessment by the mean positron lifetime is demonstrated.