测试了不同硬度P91钢试样在20，540，560℃下的拉伸性能和540，560℃下的持久强度，基于P91钢在一定温度和硬度下持久强度-断裂时间曲线近似平行的本质特征建立了不同硬度P91钢的持久强度与断裂时间的线性方程；采用该线性方程，基于不同硬度试样的短时持久数据拟合得到全寿命周期的持久强度-断裂时间曲线，对比分析了持久强度拟合结果与试验结果。结果表明：拟合得到的长时持久强度与试验结果的相对误差不大于6%，拟合准确性较高；通过短时持久数据获取不同硬度P91钢的全寿命持久强度-断裂时间曲线，可以在不破坏部件完整性的情况下对硬度异常P91钢部件的持久强度进行评估。

Tensile properties at 20, 540, 560 ℃ and stress-rupture strength at 540, 560 ℃ of P91 steel specimens with different hardness were tested. On the basis of the approximate parallel nature of stress-rupture strength versus rupture time curves of P91 steel at certain temperatures and hardness, the linear equation of stress-rupture strength and rupture time was established for P91 steel with different hardness. By using this linear equation, the stress-rupture strength versus rupture time curves of whole life cycles were obtained by fitting the short-term stress-rupture data of different hardness specimens, and the fitting results of stress-rupture strength were compared and analyzed with the test results. The results show that the fitted stress-rupture strength had relative errors of less than 6% comparing to the test results, indicating relatively high fitting accuracy. By obtaining the full-life stress-rupture strength versus rupture time curves of P91 steel with different hardness with short-term stress-rupture data, the stress-rupture strength of P91 steel parts with abnormal hardness can be evaluated without destroying the integrity of parts.