Electrolitic Nickel Rust

[Aubryann]

What could cause rust spots on .00015-.00025 electrolitic
Nickel over 1008-1010 COLD Rolled Steel?

Parts are packages in sealed tight plastic bags after a lag period of 24 hours. They were shipped to Mexico, so I know that things will be sketchy with the tempeture change, but any ideas would help me out.

Thanks in advance- AT

 

[kenvlach]

Porosity in the very thin plating, and humidity & surface moisture on the part are causing the rust.

0.00015-.00025" (I presume) is only 4-6 microns; minimum thickness in ASTM B689 is 5 microns (Class 5). QQ-N-290A has nickel plating minimums 0.00020" for copper substrates, 0.00040" on steel.

Suggestions:
Verify proper pretreatment of the steel substrate, per ASTM B183.
Verify plating procedures.
Use thicker Ni.
Include porosity testing of the plated parts as part of your QC. See ASTM B689; simplest is the hot water test: Immerse the part in 85 ^oC water for 1 hour, blow dry with clean air & check for black spots & red rust.
Bag the parts while slightly warm using dried air. Dry N₂ would be better.

 

[EdStainless]

There may be debris in the platting bath causing the flaws. For thin platting everything must be very clean.
Is there a Cu flash under the Ni?

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[Aubryann]

thanks for your comments. I beleive that there is a CU flash, but I need to have my QC check the samples out before we know for sure- thanks again. This is a very helpful forum as always.-AT