Creep behavior of Alloy 709 at 700 °C

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:762

Article

Taylor, Martin¹  Ramirez, Jose²  Charit, Indrajit¹  Potirniche, Gabriel P.²  Stephens, Robert²  Glazoff, Michael V.³ 

[1] Univ Idaho, Dept Chem & Mat Engn, Moscow, ID 83844 USA

[2] Univ Idaho, Dept Mech Engn, Moscow, ID 83844 USA

[3] Idaho Natl Lab, Idaho Falls, ID 83401 USA

关键词: Alloy 709;    Austenitic stainless steel;    Creep;    Microstructure;   

DOI  :  10.1016/j.msea.2019.138083

来源: Elsevier

【 摘 要 】

Alloy 709 is an austenitic stainless steel with potential for structural applications in advanced nuclear reactors. In this study, creep tests on Alloy 709 specimens were performed at a temperature of 700 degrees C under applied stresses in the range of 125-250 MPa. The alloy exhibited a brief primary, insignificant secondary and prolonged tertiary creep stages. A Norton stress exponent (n) of 5.9 +/- 0.7 was obtained from the double-logarithmic plot of minimum creep rate versus stress. Microstructural analyses were carried out for both as-received and crept specimens using optical microscopy, electron backscattered diffraction, and transmission electron microscopy. The microstructures of the as-received and crept specimens were compared. The mode of fracture was trans granular as revealed by scanning electron microscopy of the creep-ruptured specimens. Thermodynamic and precipitation modeling was performed in order to obtain information on the phase types and the kinetics of precipitation for the sigma - phase and the M23C6 carbide. Based on the creep data, microstructural observations and relevant modeling, creep deformation and failure mechanisms at the considered temperature are elucidated.

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