ABSTRACT Multiaxial creep behaviour of 304HCu austenitic stainless steel was studied at 973 K, 200 MPa by varying depth of U-notches from 1.67 to 3 mm, keeping the root radius of 1.25 mm on cylindrical specimen. Rupture life increased with notch depth and showed a peak value for 2.5 mm depth followed by rapid decrease, indicating the tendency towards notch weakening instead of strengthening. Creep rupture ductility decreased progressively with notch depth, resulting predominantly ductile dimple for shallow depth of notch and creep cavitation induced brittle fracture for deeper notch. Finite element analysis of stress and strain distributions across the notch along with SEM fractography and Electron Backscatter Diffraction (EBSD) studies was carried out to assess the effect of notch depth on creep rupture life. Creep strain concentration through Kernel Average Misorientation (KAM) map also supported the above views of creep strain accumulation which influence creep rupture life of notched specimens.

中文翻译：

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缺口深度对304HCu奥氏体不锈钢蠕变断裂行为的影响

摘要 304HCu 奥氏体不锈钢的多轴蠕变行为在 973 K、200 MPa 下通过​​从 1.67 到 3 mm 改变 U 型缺口深度进行了研究，在圆柱形试样上保持 1.25 mm 的根部半径。断裂寿命随着缺口深度的增加而增加，并在 2.5 毫米深度处出现峰值，然后迅速下降，表明缺口趋于弱化而不是加强。蠕变断裂延展性随着缺口深度的增加而逐渐降低，导致缺口深度较浅的主要是韧性凹坑，而较深的缺口则蠕变空化引起脆性断裂。对缺口上的应力和应变分布进行有限元分析以及 SEM 断口和电子背散射衍射 (EBSD) 研究，以评估缺口深度对蠕变断裂寿命的影响。