90Ksi would not be heat treated material so I offer this. Most of the time the PWHT (stress relief) temp will be 1050'F @ 1hour/inch max cross section. Max 200'F/Hr up/down ramp above 600'F. But for caution you must consider these questions.

What really was its condition? Annealed or Heat treated? If so what is the hardness?

If it be heat treated (Hardened & tempered) you need to know the hardness to determine the tempering temperature not to exceed.

If it is less than 32-36RC it will have been tempered at a temp greater than 1050'F so the above will work.

If you adopt vibratory stress relief, Maybe It is unnecessary to consider of the Spec.  It is OK for any metal workpiece