ABSTRACT Tapered specimens were used for an accelerated test technique to study the crack initiation of high Si stainless steel by means of constant elongation rate tensile testing in a simulated pressurised water reactor environment. Detailed crack density distributions were obtained by applying an advanced crack detection algorithm on iteratively displaced scanning electron microscopy pictures featuring stress corrosion cracks along the specimen’s gauge length. By means of finite-element analysis, prominent peaks in the crack density graphs are demonstrated to be related to stress relief and stress build-up during the crack initiation phase. Intrinsic scatter related to the crack detection suggests that stress corrosion cracking is independent of the strain-rate for strain-rates lower than 10−6 s−1. Based on the extrapolation to constant load conditions, the critical threshold value for the duplex high Si stainless steel is estimated to be around 580 MPa.

中文翻译：

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锥形高硅不锈钢试样中的裂纹萌生——应力阈值分析

摘要 锥形试样用于加速试验技术，通过在模拟压水反应堆环境中进行恒定伸长率拉伸试验来研究高硅不锈钢的裂纹萌生。详细的裂纹密度分布是通过在迭代位移扫描电子显微镜图片上应用先进的裂纹检测算法获得的，该图片具有沿试样标距长度的应力腐蚀裂纹。通过有限元分析，裂纹密度图中的突出峰值被证明与裂纹萌生阶段的应力释放和应力积累有关。与裂纹检测相关的固有散射表明，对于低于 10-6 s-1 的应变率，应力腐蚀开裂与应变率无关。