Titanium Heat Treat / Aging

[legrand01]

We have a part that has a specific callout on the drawing regarding the processes applied to a Titanium 6-2-4-2 part. We callout that the stock must be processed to meet AMS-H-81200 Heat Treat Table 1 and then Aged per Table 3.

Table 1 says to take the material to around 1600°F and air cool.
Table 3 says to age at around 1100°F for a few hours.

We sent the non-heat treated bars to a heat treating company and they only processed the bars per Table 3 (the Aging process). They are stating that that accomplishes what is required whether or not the bars have been heat treated. The bars were never "processed per Table 1".

My materials background isn't that deep, but this doesn't sound correct to me. Are they fudging the truth, or does it really not matter?

Thanks for the assistance!

 

[metengr]

According to information from ASM Handbook, Volume 4 Heat Treating, for Ti-6242 this material responds to solution treatment and aging. This means the material must be heated to the proper solution treatment temperature (1750-1800 deg F ) for 1 hour, air cooled and aged at 1100 deg F for 8 hours. '

Regarding your wording for the specification, I normally don't see 'around' 1600 deg F. If the material specification requires a solution treatment at 1600 deg F this must be done if you are required to follow it. Tell the heat treater this is what is required.

 

[EdStainless]

What was done may or may not work for a couple of reasons:
1. The original anneal may have been done at a different temperature to facilitate machining or just to be easier to do.
2. Some alloys don't like long time delays between anneal and aging. They start to age on their own and the properties come out odd.

One issue with any aged alloy is that in many cases the room temperature tensile properties look fine, but you have no idea if the other characteristic are what you expect (fatigue, toughness, elevated temp strength).

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