Ti-6Al-4V (ASTM F620) Anneal Cooling Rate

[BiPolarMoment]

I have the dubious honor of trying to assess the impact to several of our technical standards which turned into pandora's box. Turns out we have three vendors annealing using three different sets of parameters. As we are generally satisfied with the product(s) I see no reason to upset the apple cart so in reality I'm just trying wrap my head around the potential differences. While the temperature varies somewhat between the procedures they all fall within the parameters for AMS 4931 (1300-1400 deg F); the difference that may be the most important is that there are three different cooling methods (note: AMS 4931 specifies in air). (1) is in air, (2) is using nitrogen under positive pressure and (3) is in vacuum. I imagine you could claim (1) and (2) are equivalent lacking additional information but (3) is a definitive outlier. Should there be a difference expected?

 

[EdStainless]

There could be a difference. The cooling in vacuum does concern me.
You may need to test more than just tensile properties, things such as toughness and fatigue may be good indicators.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[metengr]

Develop a test plan and find out.

 

[BiPolarMoment]

Sorry for not following up. The biggest concern here isn't so much the difference between the three methods because the parts are independent of each other (aside from referencing a common standard). Likewise, the cooling in vacuum isn't in itself a problem since that's "how it's always been done". However, the vendor also changed the heat dwell time at some point and I'm not (yet) aware that there was an assessment for that change or any communication to my company (we didn't revise the drawing, but it wasn't specific enough in the first place).

There is, obviously, a concern that somehow we have several interpretations of a 'standard' but that's a different dragon to slay.

In any case, I'm consulting with people above my pay grade later this week.

Thanks for the input.