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Electroless nickel plating of SST

August 5, 2010

I have some 17-4 SST parts that have been thru the Kolene QPQ process. Pre hardness is 25 Rc and post hardness is 36 Rc. I would like to have these parts electroless nickel plated. Will the hardness of the material have an effect on the plating process? If the parts were annealed before plating would that effect the outcome of the process?

Dan Rue
QA Manager - Minneapolis, Minnesota, USA

August 11, 2010

The Kolene web site does not list a named QPC product. What is the purpose, descaling or hardening?
You may have to find a good activating material/process. You probably will need to use a Woods nickel strike before the EN. Other than that, you should not have a problem.
An annealing step will probably only make the activation more difficult.

James Watts
- Navarre, Florida

August 16, 2010

Dear Dan Rue,

I don't think the hardness will drop.

QPQ (Quench + Polish + Quench) will happen @ app 430 deg. C,
in Electroless Nickel plating will happen @ app 75 degree C.
I don't think this temperature will drop the hardness, Still you want to increase the Surface hardness keep the parts @ 200 degree for 2 hours in the oven , you will get the increased in the nickel layer hardness.
if, you are going for more than 200 C, base material (before plating) hardness will drop.

Kannan B
- Salem, Tamilnadu, India

August 19, 2010

James: If you go to www.finishing.com/library/qpq/ you can read all about their process. We chose this process because our parts needed to be matte black in color. The fact that they got harder is a bonus. What we didn't know is that the process leeches out chromium from the 17-4 SST and makes it unable to pass a MIL-spec salt spray test.

Dan Rue
- Minneapolis, Minnesota

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