Conditions causing Hydrogen embrittlement in Elgiloy

[kevlar49]

I have a procedure for the removal of lead coating from Elgiloy wire. It involves using hydrofluoric acid and nitric acid. Is there a concern for hydrogen embrittlement? The material is likely to be made from AMS 5833 which will have about a 46 HRC minimum (no max). NACE MR0175 recommends less than HRC 60 to avoid SSC.

 

[CoryPad]

Yes there is a concern. You should do a baking operation after the acid process to avoid embrittlement.

 

[EdStainless]

And don't stress the parts in between the steps. Strip, rinse, bake, then do whatever else you need to do.

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Plymouth Tube

 

[kevlar49]

What bake out procedure would you suggest? AMS 2759/9? Is there a threshold (HF concent, pH, temp, etc) above which hydrogen embrittlement is likely but below which is unlikely?

 

[CoryPad]

I am sure there is a threshold, you can contact the material supplier for their help with that information. The material itself is quite resistant to attack, so the baking is really just good practice to avoid low probability damage. There are several standards out there that cover embrittlement relief for steel parts, such as AMS 2759/9, ASTM B850, ISO 9588, and SAE/USCAR-5. I think this can be done with a simple exposure of one hour at 110 [°]C [±] 5 [°]C.