DIN 50024:2025-07

This document specifies a method for determining the condition of the passive layer through a color change using a KorroPad®, which is based on the detection of iron ions using an indicator solution. The KorroPad® method is suitable for the comparative testing of stainless steel surfaces with regard to the formation of their passive layer. It can be used to test both surfaces on which the passive layer has independently formed under atmospheric conditions following the manufacturing or processing process, as well as surfaces on which passivation has been supported by specific post-treatment measures (such as pickling and passivation). The test method is primarily surface-specific and has been extensively tested for all common stainless steels with a pitting resistance equivalent of 18 to 26. In the case of steel grades with different pitting resistance equivalents, it must be determined whether an adjustment of the KorroPad® composition is required. This document is not applicable for the corrosion resistance testing of stainless steels for their respective areas of application. This document has been prepared by Working Committee NA 062-01-77 AA "Korrosionsprüfverfahren" ("Corrosion testing") at DIN Standards Committee Materials Testing (NMP).