Stainless Steel Corrosion Fatigue
The effect of the environment is shown by comparing the variation of fatigue-fracture stresswith the number of stress cycles applied in air and in the environment of interest.
The corrosion-fatigue strength is the stress at
which no failure occour after 10^7 or 10^8 cycles or some other experimentally feasible number of cycles;this value is not the corrosion-fatigue limit.
It is, however, a convenient approbation of the stresslevel below which no failure can occur.
If the test specimencontains a notch that acts as a stress raiser, the fatigue limits in air and in the test environment are reduced.
Pitting, intergranular corrosion, and stress corrosion can produce stress raisers.
For stainless steelsand higher alloys tensile strength is the most important property relating to resistance to
For example, increasing tensile strength by precipitation hardening improves corrosion-fatigue strength.
The factors that follow have a detrimental effect on corrosion-fatigue strength:
1, Sensitizing heat treatments of both austenitic and martensitic stainless steels
2. A surface stress raiser
3. A pH 3 which results in a 50% reduction of the corrosion-fatigue strength of cold-worked Type 316L.
source - MIL-HDBK-735
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