2. Getting involved
3. Standards Committees
4. NMP

DIN Standards Committee Materials Testing

Overview

There is seldom a direct relation between resistance to the action of salt spray and resistance to corrosion in other media. The different factors influencing the progress of corrosion vary greatly with the conditions encountered. These include, for instance, the formation of protective films. Therefore, the test results should not be regarded as a direct guide to the corrosion resistance of the tested metallic materials in all environments where these materials might be used. Different materials could potentially behave differently with respect to resistance to corrosion during the test than they do when put into practice. Nevertheless, the method described gives a means of testing that the comparative quality of a metallic material, with or without corrosion protection, is maintained. Salt spray tests are generally suitable as corrosion protection tests for rapid analysis for discontinuities, pores and damage in organic and inorganic coatings. In addition, for quality control purposes, comparison can be made between specimens coated with the same coating. As comparative tests, however, salt spray tests are only suitable if the coatings are sufficiently similar in nature. It is often not possible to use results gained from salt spray testing for comparison of the long-term behaviour of different coating systems, since the corrosion stress during these tests differs significantly from the corrosion stresses encountered in practice. This International Standard specifies the apparatus, the reagents and theprocedure to be used in conducting the neutral salt spray (NSS), acetic acid salt spray (AASS) and copper-accelerated acetic acid salt spray (CASS) tests for assessment of the corrosion resistance of metallic materials, with or without permanent or temporary corrosion protection. The standard also describes the method employed to evaluate the corrosivity of the testcabinet environment. The standard does not specify the dimensions of test specimens, the exposure period to be used for a particular product, or the interpretation of results. Such details are provided in the appropriate product specifications. The salt spray tests are particularly useful for detecting discontinuities, such as pores and other defects in certain metallic and organic coatings as well as anodic oxide and conversion coatings. The neutral salt spray test is the test method in which a 5 % sodium chloride solution in the pH range from 6,5 to 7,2 is atomized under controlled conditions. It particularly applies to: - metals and their alloys, - metallic coatings (anodic and cathodic), - conversion coatings, - anodic oxide coatings, and - organic coatings on metallic materials. The acetic acid salt spray test is the test method in which a 5 % sodium chloride solution with the addition of glacial acetic acid in the pH range from 3,1 to 3,3 is atomized under controlled conditions. It is especially useful for testing decorative coatings of copper + nickel + chromium, or nickel + chromium. It has also been found suitable for testing anodic coatings on aluminum. The copper-accelerated acetic acid salt spray test is the test method in which a 5 % sodium chloride solution with the addition of copper chloride and glacial acetic acid in the pH range from3,1 to 3,3 is atomized under controlled conditions. It is useful for testing decorative coatings of copper + nickel + chromium, or nickel + chromium. It has also been found suitable for testing anodic coatings on aluminum. All salt spray methods are suitable for checking that the comparative quality of a metallic material, with or without corrosion protection, is maintained. They are not intended to be used for comparative testing as a means of ranking different materials relative to each other with respect to corrosion resistance. The committee responsible for this standard is NA 062-01-71 AA "Korrosion und Korrosionsschutz" ("Corrosion and corrosion protection") at the Materials Testing Standards Committee (NMP) at DIN. It has been prepared in collaboration with Working Committee NA 002-00-07 AA "Allgemeine Prüfverfahren für Beschichtungsstoffe und Beschichtungen" ("General test methods for coating materials and coatings") of the Coatings and Coating Materials Standards Committee (NAB) at DIN.

Document: references other documents

Document: referenced in other documents

Responsible national committee

NA 062-01-77 AA - Corrosion testing  

Responsible european committee

CEN/TC 262 - Metallic and other inorganic coatings, including for corrosion protection and corrosion testing of metals and alloys