Chromium plating resistance to salt water

Is there a 'simple' calculation to give approximate exposure time to salt (sea) water for a given thickness of chromium plating before red rust will begin to show? I have seen in letter #30106 that 13 microns should give upto/at least 120 hours for example.

The application for hard chrome for sea water itself is totally wrong. A nickel base with chrome might survive longer. Anyway the chrome depletion depends on the thickness of coating over a certain area and also is connected to microporosity and hydrogen entrapment in coating.

Hello... There is some factors your question's answer. For example, How and which feature have under chrome nickel coating layer? We don't know this. And why don't you consider this? Because,there is some special coatings nickel over chrome and also this species direct effect the corrosion resistance. For example,you can use, Microdiscontinuous chromium, Microcracked chromium, Microporous chromium.This species depend on cracks/mm rate. This rate effect corrosion. If I tell you more detail, this page won't enough. So your question's answer not easy as your estimates. I advice you, If you accept it,you must search some literature. And last,anybody give certain answer to this question because depend on a lot of factor.

Good Luck...