15-5 ph passivation & corrosion after salt spray test

[maya04]

dear all
we perfom passivation per astm a-967 on screws
made from 15-5.
when we test them for two hours in salt spray we get rust

could you advise please
thanks

 

[TVP]

The passivation process was not performed correctly if the screws are rusting after only 2 hours of exposure to salt spray.

 

[maya04]

Thanks TVP
thats what I wanted to hear
the passivator told me that for 15-5 two hours are too aggresive....

 

[unclesyd]

Can you comeback with the process you use to produce the fastener as well as the secondary operations like the passivation, etc. Need to know concentration times and t4 temperature of the secondary operations.

 

[maya04]

Hi unclesyd
about the process for the fasteners Im not sure (Ill find out and get back to you) about the passivation it was per ASTM 967 Nitric I
(what is t4 temp?)

 

[unclesyd]

15-5 is easily passivated and as posted above there is probably something amiss in the procedure. either in pickling or passivisation.
If you are pickling it the time, temperature, and concentration could wrong. The passivisation step is also open to problems especially if your pickling step is excessive. As in pickling, time, temperature, and concentration are important.
Awaiting your response.

 

[EdStainless]

Do you use any method other than salt spray to verify passivation? There are other tests.

Yes, it should pass no problem. Either they were very bad to start with or the passivation was not correct.

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Plymouth Tube

 

[photoengineer]

Sounds like a problem with the passivation technique, as 15-5 should be resistant to salt water spray.

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