The high creep strength of advanced boron alloyed 9 wt% Cr steels results from a precipitate stabilised martensitic microstructure. Grain boundaries and sub-boundaries are effectively pinned by boron stabilised precipitates. However, during creep exposure several degradation mechanisms with regards to precipitates are active such as, particle coarsening, phase transformations, dissolution of precipitates and precipitation of new phases. This diffusion driven phenomena affect the type, size and distribution of precipitates and lead to a deterioration of creep strength with increasing time of exposure. Within this work, an experimental melt of a 9Cr3Co3WVNbBN steel grade was investigated in terms of microstructural evolution during creep and aging and electrochemical behaviour. Creep specimens, tested up to 24,606 h were analysed to quantify the microstructural and electrochemical behaviour of the grip and the necked portion of the creep exposed specimens by z-phase indication of the main precipitates and Electrochemical potentiodynamic reactivation (EPR)-test. The change in diameter, phase fraction, number density and current density was quantified. The results of microstructural changes during creep exposure are compared with the electrochemical response of the specimens in the EPR-test. By understanding the correlation between microstructural changes and the results of the EPR-test, a possibility for a nearly non-desctructive on-site evaluation of the creep state of power plant components might be possible in future.

先进的硼合金9 wt％Cr钢的高蠕变强度是由析出物稳定的马氏体微观结构引起的。硼稳定的沉淀物有效地固定了晶界和亚界。然而，在蠕变暴露期间，关于沉淀的几种降解机制是活跃的，例如颗粒粗化，相变，沉淀的溶解和新相的沉淀。这种扩散驱动的现象会影响析出物的类型，大小和分布，并导致蠕变强度随暴露时间的延长而降低。在这项工作中，对9Cr3Co3WVNbBN钢等级的实验熔体进行了研究，涉及蠕变和时效过程中的微观组织演变以及电化学行为。蠕变试样，经过测试最多24个，Ë lectrochemical p otentiodynamic [R eactivation（EPR） -试验。定量了直径，相分数，数密度和电流密度的变化。在EPR测试中，将蠕变暴露过程中的微观结构变化结果与样品的电化学响应进行了比较。通过了解微观结构变化与EPR测试结果之间的相关性，将来可能对发电厂组件的蠕变状态进行几乎非破坏性的现场评估。