Abstract
A structural characterization of sensitized Alloy 690 has been carried out. Alloy 690 was solution annealed (SA; 1100 °C for 30 min, water quenched, WQ) and sensitized at 700 °C for 5, 12, 24, 36, 48 and 72 h, followed by water quenched. Techniques employed included scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction and corrosion weight-loss tests. It was found that the cubic Cr 0.19Fe 0.7Ni 0.11 phase was the main component in all the conditions. In addition, a grain refinement was observed when the aging time was increased; but after 48 h of aging, a discrete, semicontinuous network of Cr 23C 6 precipitates was detected by X-ray diffraction, in addition to the NiCrO 4, Ni 9S 8 and (Fe,Ni) 9S 8 phases found by TEM at the grain boundaries, making this alloy more susceptible to intergranular attack (IGA). After 72 h of aging, chromium continues diffusing, “back-filling” the prior depletion profile, recovering the IGA resistance.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
