DIN 50958:2012-12

The procedure described in this standard serves as a test for corrosion resistance, particularly for objects made of aluminium materials and steel with nickel-chromium or copper-nickel-chromium coatings, for objects made of zinc alloy die casting with copper-nickel-chromium coatings and objects made of copper or copper materials with nickel-chromium coatings. The revised edition of DIN 50958 does not contain the corrodkote procedure specified in DIN EN ISO 4541, but rather the modified corrodkote procedure which at that time was developed based on AST M B 380-65 and which is used primarily in Germany. The "modified corrodkote procedure" differs from the procedure specified in DIN EN ISO 4541 in the following essential points: a) DIN EN ISO 4541 indicates a temperature of (38 ± 1) °C and a relative humidity from 80 % to 90 %. In contrast, this standard indicates a temperature of (40 ± 3) °C and a relative humidity of 100 %. This climate is easier to maintain and corresponds to what has been commonly practiced in Germany. b) The specification of the applied slurry being allowed to dry at a relative humidity of less than 50 % has not been adopted in this standard. According to previous experience these deviations have no influence on the test results of the modified corrodkote procedure. c) The thickness of the wet slurry shall be approximately 50 µm. In contrast, DIN EN ISO 4541 indicates a higher thickness - between 80 µm and 200 µm - of the wet slurry. d) Unless specified otherwise, the test specimens shall be stored for 16 h in the climatic chamber which shall not be opened during this period. In contrast, DIN EN ISO 4541 indicates an exposure period of up to 16 h during which the climatic chamber shall not be opened except for short interruptions necessary to place or remove (other) test specimens. e) After testing the corrosion spots are made visible after exposure for 24 h in a condensation atmosphere with constant humidity (CH) in accordance with DIN EN ISO 6270-2 or an exposure for 4 h in a neutral salt spray (NSS) test in accordance with DIN EN ISO 9227. In contrast, DIN EN ISO 4541 indicates an exposure period of 4 hours in a salt spray cabinet in accordance with ISO 3768 or exposure at 38 °C and 100 % relative humidity in a humidity chamber in order to make corrosion spots visible. This standard has been prepared by Working Committee NA 062-01-61 AA "Mess- und Prüfverfahren für metallische und andere anorganische Überzüge" ("Measuring and test methods for metallic and other inorganic coatings") of the Materials Testing Standards Committee (NMP).