page_title: Corrosion fatigue
section_title: Stress-corrosion fatigue
hierarchical_section_title: Corrosion fatigue / Crack-propagation studies in corrosion fatigue / Stress-corrosion fatigue
caption_attribution_description: English: True corrosion fatigue and stress corrosion fatigue-combined effect
context_page_description: Corrosion fatigue is fatigue in a corrosive environment. It is the mechanical degradation of a material under the joint action of corrosion and cyclic loading. Nearly all engineering structures experience some form of alternating stress, and are exposed to harmful environments during their service life. The environment plays a significant role in the fatigue of high-strength structural materials like steel, aluminum alloys and titanium alloys. Materials with high specific strength are being developed to meet the requirements of advancing technology. However, their usefulness depends to a large extent on the degree to which they resist corrosion fatigue.
  The effects of corrosive environments on the fatigue behavior of metals were studied as early as 1930.
  The phenomenon should not be confused with stress corrosion cracking, where corrosion leads to the development of brittle cracks, growth and failure. The only requirement for corrosion fatigue is that the sample be under tensile stress.
context_section_description: In materials where the maximum applied-stress-intensity factor exceeds the stress-corrosion cracking-threshold value, stress corrosion adds to crack-growth velocity. This is shown in the schematic on the right. In a corrosive environment, the crack grows due to cyclic loading at a lower stress-intensity range; above the threshold stress intensity for stress corrosion cracking, additional crack growth (the red line) occurs due to SCC. The lower stress-intensity regions are not affected, and the threshold stress-intensity range for fatigue-crack propagation is unchanged in the corrosive environment. In the most-general case, corrosion-fatigue crack growth may exhibit both of the above effects; crack-growth behavior is represented in the schematic on the left.
caption: Combined true-corrosion and stress-corrosion fatigue
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