A question:
You still haven't clarified what "recently obtained" means.
A Charpy curve will be of little help to you I would think if you don't have weld parameters to go along with it. You are after all testing the welds and not the BM.
And after doing a search on T-1 and realizing it contains Cr, Ni, Mo, V, and B, in reasonably large amounts, there's no telling what kind of soup you have in the weld metal, especially mixed with high Mn and Si from the S-6.
You have elements that respond well to Q and T. And that is exactly what takes place in a multipass weldment. So I suppose with all of this variety of elements, a multi pass application and no telling what mircrosturctures were emphasized in each Charpy bar, it could be argued that erratic results would be inevitable.