Fatigue Testing of Metallurgically-Bonded EBR-II Superheater Tubes

Totemeier, Terry C.

Idaho National Laboratory

关键词: Crack Propagation;    Fatigue;    36 - Materials Science;    Air;    Metallurgical Bonding;   

DOI  :  10.2172/911861
RP-ID  :  INL/EXT-06-12011
RP-ID  :  DE-AC07-99ID-13727
RP-ID  :  911861

美国|英语

来源: UNT Digital Library

【 摘 要 】

Fatigue crack growth tests were performed on 2¼Cr-1Mo steel specimens machined from ex-service Experimental Breeder Reactor – II (EBR-II) superheater duplex tubes. The tubes had been metallurgically bonded with a 100 µm thick Ni interlayer; the specimens incorporated this bond layer. Tests were performed at room temperature in air and at 400°C in air and humid Ar; cracks were grown at varied levels of constant ?K. Crack growth tests at a range of ?K were also performed on specimens machined from the shell of the superheater. In all conditions the presence of the Ni interlayer was found to result in a net retardation of growth as the crack passed through the interlayer. The mechanism of retardation was identified as a disruption of crack planarity and uniformity after passing through the porous interlayer. Full crack arrest was only observed in a single test performed at near-threshold ?K level (12 MPa?m) at 400°C. In this case the crack tip was blunted by oxidation of the base steel at the steel-interlayer interface.