Thanks for the response SJones. I believe i found something a little closer to what i was looking for though.
From PED technical note 2006-03 rev.4 on PED impact testing exemption:"Refer to the curves in Fig. UCS-66 to estimate the impact properties. The curves establish the temperature at which an impact value of 15 ft.-lbs. (20 J) may be assumed."
So it may not be exact but it gives one a good idea of what they are looking at.