Tension and creep rupture behaviors of long-term exposed P91 steel, sampled from of a T-fitting part of reheat steam piping serviced for 73,716 h at 569 °C and 46.7 bars in a supercritical plant, were evaluated in comparison with those of virgin Gr. 91 steel. Tensile strength reduction factors were proposed for the exposed P91, and creep rupture behaviors were analyzed using various creep laws: Norton’s power law, the Monkman-Grant relations, and a damage tolerance factor (λ). The exposed P91 revealed a significant reduction in tensile strengths, but an increase in elongation. It was found to have a lower creep strength, faster creep strain rate, and higher rupture ductility than the virgin steel. The reduction of mechanical strengths in the exposed P91 was due to the coarsening of precipitates, dissolution of useful fine MX precipitates, and recovery of dislocation substructure during the long-term thermal exposure.

与超纯Gr相比，评估了长期暴露的P91钢的拉伸和蠕变断裂行为，该曲线是从在569°C和46.7 bar下用于763,716 h的再热蒸汽管道的T型装配部分中采样的，评估时间为46.7 bar。 。91钢。提出了暴露的P91的拉伸强度降低因子，并使用各种蠕变定律分析了蠕变断裂行为：诺顿幂定律，蒙克曼-格兰特关系和损伤容限因子（λ）。暴露的P91显示出抗张强度的显着降低，但伸长率却有所提高。与原始钢相比，发现它具有更低的蠕变强度，更快的蠕变应变速率和更高的断裂延展性。暴露的P91中机械强度的降低归因于沉淀物的粗化，有用的MX细小沉淀物的溶解以及长期热暴露期间位错亚结构的恢复。