“New Mechanical and Thermal Processes for Mitigating Stress-Corrosion and Corrosion-Accelerated Fatigue” J. S. Porowski, W. J. O’Donnell, M. L. Badlani, E. J. Hampton, and B. Kasraie, presented at ASME Pressure Vessel and Piping Conference, San Diego, California, June 24, 1991, International Journal Pressure Vessel & Piping, No. 50 (1992) pp. 63-79.
This paper describes new mechanical and thermal processes which have been developed and verified to mitigate stress-corrosion cracking and corrosion-assisted fatigue in operating plants. These processes inhibit the initiation of cracks in as-fabricated components and piping systems. They can also prevent the further growth of cracks initiated before application of the process provided that the stresses that the stresses be kept the threshold values for crack propagation.
These processes introduce high residual compression, thus reducing the effective operating stresses which propagate existing defects or cracks. Both the mechanical and thermal processes described herein were conceived from basic theoretical considerations regarding the elastic-plastic behavior of pressure vessels, piping, and structural materials. Due to small magnitudes of applied plastic strains, the metallurgical properties of the materials are not essentially altered by either process. residual tensile stresses, which enhance crack initiation and propagation, are replaced by residual compressive stresses, which inhibit crack initiation and propagation.
Bill O’Donnell, Sr. is active on the ASME Subgroup on Elevated Temperature Design, and the Subcommittee on Design – as well as a Contributing Member of the ASME (BPV III) Working Group on Fatigue Strength.
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