A new methodology for analysis of creep and creep fracture data for 9–12% chromium steels
A new methodology for analysis of creep and creep fracture data for 9–12% chromium steels
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DOI：
10.1179/174328008x254349
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发表时间：
2008-03
影响因子：
16.1
通讯作者：
B. Wilshire;P. J. Scharning
中科院分区：
文献类型：
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作者：
B. Wilshire;P. J. Scharning
对常用来量化蠕变和蠕变断裂行为的方法进行了严格的审查。它们的局限性通过参考三种马氏体钢（即 91、92 和 122 级）的公开信息来说明。采用传统程序，这些 9-12% 铬钢的蠕变设计强度已大大降低，因为持续的实验计划已将最大测试持续时间从 ∼30 000 小时增加到 100 000 小时。此外，即使应用于综合长期数据集，估计的 100 000 小时强度也会有很大差异，具体取决于选择执行计算的详细方法。相比之下，通过适当的极限拉伸强度 (UTS) 值对施加的应力进行归一化，新的关系允许使用合金钢基体中晶格扩散的激活能 (300 kJ mol−1) 将不同蠕变温度下的多批次应力断裂特性叠加到 S 形“主曲线”上。这样，通过持续小于 30 000 小时的蠕变寿命测量值的外推，可以准确地预测从大规模试验程序中确定的最新 100 000 小时强度，甚至对于长达 5000 小时的失效时间也能获得合理的估计。因此，通过分析不同钢和其他抗蠕变合金已经产生的结果来验证新方法将限制当前获取长期工程设计数据的程序的规模和成本。
The approaches commonly used to quantify creep and creep fracture behaviour are critically reviewed. Their limitations are illustrated by reference to information openly available for three martensitic steels, namely, grades 91, 92 and 122. Adopting traditional procedures, the creep design strengths of these 9–12% chromium steels have been reduced substantially as continuing experimental programmes have increased the maximum test durations from ∼30 000 towards 100 000 h. Moreover, even when applied to comprehensive long-term data sets, the estimated 100 000 h strengths vary considerably, depending on the detailed method selected to perform the calculations. In contrast, by normalising the applied stress through the appropriate ultimate tensile strength (UTS) value, new relationships allow the multi-batch stress rupture properties at various creep temperatures to be superimposed onto sigmoidal 'master curves' using the activation energy for lattice diffusion in the alloy steel matrixes (300 kJ mol−1). In this way, the latest 100 000 h strengths determined from the large scale test programmes are predicted accurately by extrapolation of creep life measurements lasting less than 30 000 h, with reasonable estimates obtained even for failure times up to only 5000 h. Validation of the new methodology by analysis of results already produced for different steels and other creep-resistant alloys would therefore limit the scale and costs of current procedures for acquisition of long-term engineering design data.