ABSTRACT The creep rupture behaviours and microstructural changes of a modified 9Cr-1Mo heat-resistant steel were investigated at 853 K. Analysis of creep results suggests that dislocation climb is the dominant deformation mechanism with true stress exponent of 5 under the present conditions. Based on the microstructural analysis, strengthening contributions from M23C6 carbides and MX carbonitrides were clarified. The M23C6 carbides can promote grain boundary strengthening by exerting Zener pinning forces, whereas MX carbonitrides can enhance the creep strength by interacting with mobile dislocations to induce threshold stress. Besides, softening of the steel is related not only to the decrease of dislocations, but also the coarsening of precipitates and substructures. The value of creep damage tolerance factor is close to 6.6, which further confirms that the creep damage is mainly attributed to the microstructural degradations, such as the coarsening of precipitates and substructures and decrease of dislocations.

中文翻译：

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不同机制强化改性9Cr-1Mo耐热钢的蠕变断裂行为

摘要 研究了一种改性 9Cr-1Mo 耐热钢在 853 K 下的蠕变断裂行为和显微组织变化。蠕变结果分析表明，在当前条件下，位错攀爬是主要的变形机制，真实应力指数为 5。基于显微组织分析，明确了 M23C6 碳化物和 MX 碳氮化物的强化作用。M23C6 碳化物可以通过施加齐纳钉扎力来促进晶界强化，而 MX 碳氮化物可以通过与移动位错相互作用产生阈值应力来增强蠕变强度。此外，钢的软化不仅与位错的减少有关，而且与析出物和亚结构的粗化有关。蠕变损伤容限系数值接近6.6，