Defects in aluminum forgings
Defects in aluminum forgings
(OP)
Dear all,
I have AA7075 aluminum forgings in O1 heat treatment. Then they get machined and hardened T6. The initial forging is US controlled after 01 ht but the part can't be US controlled after T6 because of its complex shape. Can defects develop or grow between 01 and T6 heat treatments?
Thanks a lot.
I have AA7075 aluminum forgings in O1 heat treatment. Then they get machined and hardened T6. The initial forging is US controlled after 01 ht but the part can't be US controlled after T6 because of its complex shape. Can defects develop or grow between 01 and T6 heat treatments?
Thanks a lot.





RE: Defects in aluminum forgings
RE: Defects in aluminum forgings
So do you mean that any kind of heat treatment (01, T6 or other) don't generate defects? Only forging can be the origin of defects?
If so, could defects be acceptable for a class A ultrasonic testing done after forging and then become larger during T6?
RE: Defects in aluminum forgings
You need to determine if these are casting defects or forging defects.
RE: Defects in aluminum forgings
Forging can make casting defects grow, and the anneal can also.
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P.E. Metallurgy, Plymouth Tube
RE: Defects in aluminum forgings
Can we presume that You are addressing a die forging, as opposed to a hand forging or forged block?
What is the: material spec? forging spec? heat treatment spec? US-NDI spec? Fluorescent penetrant spec?
When You first-article test [random-sample] one-or-more rough-machined-HT'ed forgings for chemistry, grain, grain-flow, mechanical allowables, etc... then a lot of Your questions may be answered.
WARNING. A 'first article inspection' to verify quality/properties of the raw forging is an absolute necessity.
Question: Why -T6x... and not -T76x?? Generally 7075-T6x DFs have poor exfoliation and SCC resistance.
Regards, Wil Taylor
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RE: Defects in aluminum forgings
When you say that defect can grow due to quenching thermal stresses, do you mean that a crack can propagate or is there also a possibility for internal cavities to coalesce or become larger?
EdStainless,
There is no HT between casting and forging.
WKTaylor,
It's an open-die forging, the shape is a thck disc.
Material spec? AMS4126
Heat treatment spec? AMS2772
US-NDI spec? AMS2154
Fluorescent penetrant spec? AMS2645
T6 is to achieve the highest mechanical properties. We have no corrosion issue.
Thanks to all,
RE: Defects in aluminum forgings
No, under your stated conditions.