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

用正电子寿命谱法研究了蠕变强度增强铁素体钢的蠕变降解。平均正电子寿命的蠕变时间依赖包括初始阶段减小、中期逐渐减小和破裂前大幅度减小三个区域。这些区域几乎分别对应于瞬态、稳态和加速区域。此外，与蠕变试验前相比，初始蠕变时间的平均正电子寿命增加与蠕变试验中析出相的形成相对应。论证了用平均正电子寿命评价蠕变寿命的方法。

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.