2024-T4 vs. 2024-T351 MATERIAL

A. I believe this may be what you are looking for:

T351- Solution Heat Treated and cold worked by stretching. Equivalent to --T4 condition. It applies only to 2024 plate and rolled bar and 2219 plate per MIL-A-8920

T4- Solution Heat Treated and naturally aged to substantially stable condition. Applies only to products which are not cold worked after solution heat treatment.

A. Both have been solutionized at 920 F, water quenched and then naturally age hardened at room temperature for 4+ days. The difference: after quenching, the T351 rod was stress relieved by stretching 1-3% prior to aging. Thus, T351 is more stable for machining, as T4 still has residual stresses from quenching: compressive near the surface and tension in the center.
T4 is perhaps better in some fatigue applications.

A. T351 and T4 are temper designations of the aluminium alloy. T351 is a solution treated, cold worked and naturally aged and substantially stable condition. It is stress relieved by cold stretching to a permanent set of 1.5% to 3%.
T4 is solution treated and naturally aged to a substantially stable condition. (Definitions from ANSI 35.1)

T351 can be heat treated to T4 by heating to 495±5C (time dependent on cross sectional thickness) and the either cold water or polymer quenched (again the delay time between heat treatment and quenching is dependent on thickness, but generally the quicker into the quench the better). The material should then be naturally aged at ambient temperature for a minimum of 96 hours before being released.

Alternatively you could consider buying it in the temper state you require, try ordering SAE-AMSQQA200/3 T4.