passivation after welding 2

[engamopar]

Have a part made of 17-4ph. Will receive (2) [solid bar]
handles welded to it so that it will look like a "T" configuration. Plan to weld first, then heat treat, then grind. Passivation in Citric Acid is planned as the final operation. Normal rinse is plain old clean water - no sodium dichromate or any other types of rinses are normallly part of our process. Do we need to be concerned about any possible future localized attack in the welded area arising from the passivation process following the welding?

 

[EdStainless]

Will your heat treatment be annneal and age?
In vacuum or hydrogen?

If the parts are annealed and aged in protective atmosphere your passivation after ginding should be fine.

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[Goahead]

You may be interested in an article visible at

http://www.pfonline.com/articles/059905.html

Regards,

http://www.welding-advisers.com/

 

[unclesyd]

It has been our experience that 17/4 doesn't respond well to Citric Acid passivation. We do a lot of welding on 17/4 in H1125 or H1150 condition using the following procedure:
Weld using either 308L SS or 630 electrodes, machine, grind or lap then heat treat to the H1150 condition. We heat treat in a oven and use steam, air or oil to force the oxide tint on the 17/4.
If for some reason we want the oxide tint removed we treat the part with alkaline/permanganate then pickle in HNO3/HF, normally 15%/1 1/2%. We we deem passivation necessary we use 20% HNO3, Citric will not do the job.

You have to be careful as you will have pickling referred to as passivation and vice verse. These are two entirely different processes.

 

[engamopar]

Releative to EDSTAINLESS's response:
We purchase our raw bar stock solution annealed per AMS5643. Raw bar stock is solution heat treated, precipitation hardenable. After processing into parts we age-harden in air.

In this case age hardening will be to H1025 IAW AMS2759/3.