passivation of Titanium 3

[engamopar]

We currently passivate our cres item in accordance with the ASTM A967 and use a Citric Acid Method. NORMALLY, we passivate Cres 300 series and 17-4ph. Our passivation operator mistakenly put some Titanium items in the Passivation process- which we don't normally do.
1. They were immersed about 10 minutes.
2. The specific gravity reading is 1.015 ± .001/temp 120°-160°F
3. The parts have been both heat treated & ground
4. The heat treat requirement is 160-180 KSI.
5. The exact percent of Citric Acid is unknown -
I would expect it to be 7-10percent.
The operator rinsed them once and is going to rinse them
another 2 times.
What, if any, harm can we expect has been done here? Thanks in advance.

 

[cloa]

http://www.finishing.com/68/85.shtml

http://www.titaniumprocessingcenter.com/titanium-corrosion-data.htm

Trivial effect on the Titanium except if someone used steel embedded on the Titanium then there is a risk of hydrogen embrittlement.

 

[EdStainless]

No effect, except maybe cleaner.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[cloa]

From

http://www.parrinst.com/wp-content/uploads/downloads/2011/07/Parr_Titanium-Corrosion-Info.pdf

These are the conditions from which hydrogen embrittlement of Titanium might occur.


The pH of the solution is less than
3 or greater than 12; the metal
surface must be damaged by
abrasion; or impressed potentials are
more negative than -0.70V.(39)
2. The temperature is above 170°F
(77°C) or only surface hydride films
will form which, experience indicates,
do not seriously affect the properties
of the metal. Failures due to
hydriding are rarely encountered
below this temperature. (There is
some evidence that severe tensile
stresses may promote hydriding at
low temperatures.)(39)
3. There must be some mechanism for
generating hydrogen. This may be a
galvanic couple, cathodic protection
by impressed current, corrosion of
titanium, or dynamic abrasion of the
surface with sufficient intensity to
depress the metal potential below
that required for spontaneous
evolution of hydrogen.

Seems like it definitely won't happen due the lack of condition 2.

 

[cloa]

Though that information is for pure Titanium and I bet its TI-6-4 which less protected against HE.

 

[engamopar]

CLOA is correct: the mat'l is 6aL4v. However, I am not clear about the response"... except if someone used steel embedded on the Titanium then there is a risk of hydrogen embrittlement."
Is the reference to steel being "embedded on the Titanium" as due to our in-house processing, i.e. "free iron" depsosited from a cutting tool, or from the users, i.e. service application?
We can know about the former, but not necessarily the latter.
Thanks to all for your responses so far!