Corrosion requirements should describe the component in its intended environment. Material, coating, assembly and handling all contribute to the final result.
Barrier protection and sacrificial protection
A coating can separate the substrate from its surroundings. Zinc can also protect steel by corroding preferentially in a suitable electrolyte. The mechanism depends on the coating/substrate combination; not every metallic finish works as the same impermeable barrier.
Describe the actual exposure
State whether the part encounters condensation, rain, salt, cleaning chemicals, temperature changes or wear. Include storage and transport conditions when they matter. “Indoor” and “outdoor” alone do not describe every relevant exposure.
Specify the complete coating system
For zinc electroplating, define the zinc coating and passivation together. Include critical dimensions, appearance requirements and inspection areas. Colour does not establish a particular chemistry or corrosion performance.
Consider the assembled product
Identify mating materials, fasteners and electrical contact requirements. Dissimilar metals in electrical contact with a common electrolyte can behave differently from isolated components. Assess the assembly and any insulating or conductive interfaces as part of the design.
Connect each test to an acceptance criterion
Thickness measurement and salt spray testing answer different questions. Define the method, sample scope, inspection areas and acceptance criteria. Do not use a number of test hours as a standalone service-life promise.
Investigating an unexpected result
Record the article and batch, drawing revision, photographs, exposure and handling history. Keep observations separate from assumed causes. Agree the investigation before cleaning or reprocessing changes the surface under assessment.
Continue to salt spray testing, thickness measurement or our dissimilar-metal guide (Swedish).
Technical background: American Galvanizers Association on zinc protection mechanisms and worldstainless on galvanic corrosion.
Discuss your component
Send the drawing revision, material grade, quantity, coating and inspection requirements.
Contact YTSAB ↗