Passivation of 17/4 PH Stainless Steel 2

[macwill]

I am looking for for a definitive procedure on passivating 17-4 PH stainless steel for our cylinders. I was recently told that you don't passivate this grade as it is self passivating. The cylinders are bored and honed from double H1150 17/4,
THANKS!

 

[israelkk]

QQ-P-35 which can be found here

http://assist.daps.dla.mil/quicksearch/

 

[lgearhart]

We use the Type VIII listed in QQ-P-35. Since it doesn't have the sodium dichromate added to the nitric acid, you have far fewer control & consistency problems. It works well.

You probably know that QQ-P-35 was cancelled, and replaced by the SAE document AMS-QQ-P-35, which has been cancelled (Feb 2005) and replaced by AMS 2700. But that's all just moving words and titles around. The recipes in the QQ-P-35 listed above are still good.

And you DO want to passivate. Stray iron or steel particles that get stuck on the surface can cause the stainless steel to show surface rust, which nobody likes.