Oxide layer on EDM cut Austenitic SS

[123Cat]

How do you remove that dark oxide layer on SS
Portions of my parts are very narrow with small holes 3mm and I cannot quite get the TIG brush in the area Also ,,,
Tig brush creates heat which can warp slender parts

Can you recommend some powerful pickling ????

Thank You

 

[123Cat]

The parts are for very high vacuum work

Do I need to clean them at all ???

Will that oxide layer outgas or contaminate the vacuum in any way ???

 

[dgallup]

We EDM a lot of small holes in austenitic SS for fuel injectors. We actually prohibit any secondary operation after EDM. These last for decades with no change in flow. There is moderate vacuum in the intake manifolds.

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[EdStainless]

If there is zero concern about corrosion or fatigue then leaving the oxide and recast layer is OK.
In SS this is typically chemically cleaned by pickling. This will lightly etch the entire surface, depending on how you do it.


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P.E. Metallurgy

 

[tbuelna]

There are chemical etch processes suitable for removal of EDM recast layer, which is typically <.0005". There are also abrasive flow processes like Extrude Hone that both remove the recast layer and improve surface quality.

 

[123Cat]

Thanks
Work and health took away our hot nitric and hyroflouic bath

And a good vacuum guy said you don't put EDM wire cut surfaces in high vacuum , so that recast has to be removed somehow

Hand work does it at a time cost

 

[TugboatEng]

If you can't do it in house with pickling compounds, send it out. Electropolishing is cheap.

 

[EdStainless]

If the parts are small then you can do it with very small volumes of liquid.
You can buy pre-mixed pickle solution.
Tug's suggestion to send them out for a light electropolish is also very good.

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P.E. Metallurgy