Miscellaneous Corrosion Tests

Several tests are not related to any particular part of the corrosion process, but involve only a specific test specimen that responds to corrosion by complete failure. These tests are used in the measurement of certain forms of corrosion involving factors such as stress. Examples are corrosion fatigue, stress corrosion cracking, and hydrogen embrittlement In designing such corrosion tests, the variety of test specimens parallels the number of apphcations. 

Stress corrosion tests may use a constant appfied stress or one that changes as the crack progresses. Corrosion fatigue tests may vary in the way cyclical stresses are applied tensile only, or tension-compression. 

The commonly used test for caustic embrittlement employs an applied stress along with a technique to concentrate dissolved sohds at the critical area. When complete failure of the specimen is involved 

In summary, any corrosion test can be used to evaluate corrosion inhibitors, as long as it detects a difference in corrosion with and without the inhibitor. The most meaningful test is one that closely simulates field conditions. Sensitivity of measurements may not always produce the most useful results and requirements of the test method can vary widely depending on whether it is used in the laboratory or in the field. 

---