2024 T351 with stress relief

[jack70]

Samples of 2024-T351 had a post heat treatment at 550 F for 3 hours (oven cool) for the purpose of stress relieving.
Did this time and temp have a detrimental effect on the properties?

 

[swall]

You would have somewhat overaged the material and degraded the elongation. Can't say if this is detrimental without knowing more about your product form and application.

 

[RPstress]

According to MIL-HDBK-5 (now the MMPDS) the room temperature Ftu will have dropped to about 75% to 80% of its normal T351 value and the room temp Fty will have dropped to about 60% of its T351 value. (Figs. 3.2.3.1.1(d) and (e).)

According to fig. 3.2.3.1.5(b) the R.T. elongation may get up above 20% from its T351 value of less than 10%. This implies the elongation tests were on material about 1/2" - 1" thick.

By inference fatigue properties will be worsened (perhaps by roughly the change in Ftu).

Fracture toughness *may* have gone up a bit. I'd be curious as to other people's opinion on this.