zaist,
I do not believe that this is the best forum for this question...perhaps something in either the mechanical engineering or metallurgical groups would be better.
In response, if I assume that 1050 is approximately equal to A36 mild steel, the ASME B31series and Section VIII codes limit the usage to -20F.
This lower limit includes a temperature "margin" above the NDT zone.
My opinion only....
MJC