Intergranular stress corrosion cracks and crack tips produced in high-temperature water environments have been characterized in both Ni-base (alloy 600) and Fe-base (304 and 316SS) stainless alloys. Cracks and corroded regions are examined in cross-section using high-resolution analytical transmission electron microscopy to determine the structure and composition of crack-wall and crack-tip oxides as well as the grain boundary metallurgy immediately ahead of crack tips. Important differences are identified in corrosion characteristics between the Ni-base and Fe-base stainless alloys and as a function of the water environment and the grain boundary microstructure. These unique nanometer-scale measurements indicate corrosion and deformation processes occurring during crack advance and provide insights into mechanisms controlling environmental degradation.
Revised: September 14, 2009 |
Published: February 1, 2001
Citation
Bruemmer S.M., and L.E. Thomas. 2001.Insights into Environmental Degradation Mechanisms from High-Resolution Characterization of Crack Tips. In Chemistry and Electrochemistry of Corrosion and Stress Corrosion Cracking, 123-144. Warrendale, Pennsylvania:The Minerals, Metals & Materials Society.PNNL-SA-33694.