ASTM B117 Testing – Common Questions
1. Why do I need to run an ASTM B117 test?
ASTM B117 is a salt spray test used to produce relative corrosion resistance information for specimens of metals and coated metals exposed in a standardized corrosive environment. It is recognized internationally and widely used in the following industries: automotive, paints and coatings, aerospace, and military (as part of the MIL-STD-810 standard).
2. What information will I need to provide to the laboratory?
Before Kejian Laboratories sets up your customized test, we will need to know how many test specimens (usually 1) per product/material you wish to test, specimen dimensions, exposure duration hours, sample preparation and cleaning requirements, sample orientation, visual inspection, time intervals, and post-test evaluations. When you contact us, we will further guide you through this process.
3. What size sample should I use?
Sample size varies a lot and depends on the application. It can go from tiny screws to large sub-assemblies e.g a truck radiator with supporting brackets. You want to make sure you are testing a life-representative sample.
4. What results can I expect from an ASTM B117 test?
The results you gain from salt spray testing will allow you to gauge how well your metal, surface or coating can resist corrosion. Different metals and surfaces can exhibit differing amounts of resistance with respect to corrosion, and ASTM B117 testing will allow you to compare this. It will also allow you to judge a surface’s tendency to corrode when it is scratched (if your samples are scribed ASTM D1654) as well as the adhesion of its coating.
5. How long an exposure should I use?
The exposure time varies considerably as a function of your product application. There is no way to predict that “X” many hours in a salt spray test will simulate exactly “X” years in the field, as this test does not represent any specific real -life scenario. However the longer your sample can stay in the cabinet without showing degradation signs, the more corrosion resistant it will be. As a reference, decorative parts such as the ones found in bathrooms will often get tested for an exposure between 24 and 96 hours. Structural galvanized components used outdoors will often get an exposure of 8000-10,000 hours.
6. What secondary or follow-up tests are recommended with an ASTM B117 test?
ASTM D610 is often used to assess the rate of corrosion for steel painted samples. it is also complemented by ASTM D714 which will quantify the blistering degree of paint steel samples
ASTM D3359 is a tape adhesion test is often used to evaluate coating adhesion following the ASTM B117 salt spray fog test. Micom Laboratories offers ASTM D3359 test as part of its Coating test services. The ASTM D1654 is used as a final inspection test to determine the extent of rust creepage on your specimens.
7. Is ASTM B117 the only corrosion test available?
ASTM B117 was the first recognized test method worldwide and was published in 1939. More sophisticated techniques have been developed since then, namely the ASTM G85 – Standard Practice for Modified Salt Spray testing. This practice is actually comprised of 5 different corrosive atmospheres:
- Acetic Acid Salt spray Test (often used on decorative chromium plating on steel)
- Cyclic Acidified Salt Fog Test (exfoliation testing of some aluminum alloys)
- Acidified Synthetic Sea Water Fog Test (often used to test Aluminum alloys)
- Salt/SO2 Spray Test (exfoliation corrosion/inter granular attack)
- Dilute Electrolyte Cyclic Fog Test (Industrial Protective Coatings Evaluations)
ASTM D5894 combines the salt spray exposure with sun aging.
SAE J2334 is somewhat similar to ASTM G-85 cycle but with a different electrolyte solution
GM 9540 cyclic corrosion testing, somewhat similar to SAE J2334