What Does Salt Spray Testing Mean?
The salt spray test is an accelerated corrosion test used to measure the comparative corrosion resistance of materials exposed to a salt spray or salt fog at high temperature.
This corrosion test is intended to provide corrosion resistance information on metals and coated metals. With visual inspection following this test the suitability of coatings, paints and metals to resist corrosion or exposure to marine environments can be determined.
The salt spray test is also known as ASTM B117 and fog testing.
Corrosionpedia Explains Salt Spray Testing
In the salt spray test, samples are placed in an enclosed salt spray testing cabinet or chamber built to ASTM B117 specifications and subjected to uninterrupted indirect fog or spray of a salt water solution. This environment is maintained throughout the duration of the test. Chamber construction, testing procedure and testing parameters are standardized under national and international standards, like ASTM B117 and ISO 9227.
The temperature is maintained at 95°F (+ 34°F to 35°F) (35°C (+ 1.1°C to 1.7°C)), with a pH range of 6.5 to 7.2 and a salt atmosphere of 5 parts sodium chloride to 95 parts ASTM D1193 Type IV water, introduced into the chamber at specific air pressure. This test does not dictate the length of exposure.
The ASTM B117 Salt Spray Test standard is extensively used to measure normal corrosion resistance to ocean water type environments. Test duration depends on the specification or the corrosion resistance of the material.
The salt spray test is used to:
- Relate the corrosive resistance of various metals or finishes
- Measure the corrosive inclination when a metal or coated surface is scratched
- Determine coating adhesion and corrosion creep
- Evaluate corrosion resistance in a marine environment (wetness, temperature, salt fog)
Salt spray testing is popular as it is well standardized and rationally repeatable. Salt spray tests are extensively used for the evaluation of corrosion resistance of parts or finished surfaces in following sectors:
- Aircraft and military equipment