Corrosion of Metals & Alloys – accelerated testing involving cyclic exposure to salt mist, dry & wet conditions
This test method specifies the apparatus and procedure to be used in conducting accelerated corrosion tests for the comparative evaluation of metallic materials, with or without permanent/temporary corrosion protection, when exposed to a salt contaminated, simulated outdoor environment. It is cyclic in nature, i.e.; test specimens are exposed to changing climates over time.
Test specimens are placed in an enclosed chamber and exposed to a changing climate that comprises of the following 3 part repeating cycle. 2.0 hours exposure to a continuous indirect spray of neutral (pH 6.5 to 7.2) salt water solution, which falls-out on to the specimens at a rate of 1.0 to 2.0ml/80cm²/hour, in a chamber temperature of +35C . This is followed by 4.0 hours of air drying in a climate of <30%RH at +60C. This is followed by 2.0 hours exposure to a condensing water climate (wetting) of 95 to 100%RH at +50C. The number of cycle repeats and therefore the test duration is variable.
The maximum transition times between each part of the test cycle are also specified as follows:
From salt spraying to air drying within 30 minutes.
From air drying to wetting within 15 minutes.
From wetting to salt spraying within 30 minutes.
Chamber volumes of less than 400 Litres are not permitted by this test standard.