HYDROGEN EMBRITTLEMENT RELIEF TREATMENT

[maya04]

Hi All
I have parts from PH 17-7 SS with TH1050 (RC~38-40), it was passivated after machining but the vendor forgot to perform
HYDROGEN EMBRITTLEMENT RELIEF TREATMENT
I know that this process is to be done within 4 hours after passivation.
are those parts trash?
what can we do?

 

[metengr]

maya04;
Perform the de-embrittlement thermal heat treatment and nondestructive test( wet fluorescent MT) after this treatment to verify no delayed cracking.

 

[israelkk]

If it was machined after heat treatment and was clean without oxide or heat tint and there was no chemical cleaning to remove oxide or heat tint then the passivation itself doesn't create hydrogen embrittlement and there is no need for hydrogen embrittlement relief to my best knowledge.

However, if there was a need to chemically clean the parts before passivation then the part should be discarded if they are for aerospace or military use. It depends to what spec they were created. This is why mechanical cleaning process such as aluminum oxide blast with fine grit is preferred before passivation.

Or even best is to to heat treat and then completely final machine the part.

Sometimes it is customary to use aluminum oxide blast on the less accurate dimensions and final machining on precise dimensions.

 

[swall]

I agree with israelkk. Nitric acid (assuming the passivation was done with nitric) is such a strong oxidizer, any hydrogen formed is quickly oxidized into H2O and has no change of getting into the steel.