Hi Minja
As Metallurgy_eng said ~ 200C is generally the maximum recommended coating/part temperature during spraying for ferrous type substrates. So you need to get some idea of the temperature rise caused by a pass of the gun to know the safe surface temperature in which to continue spraying.
'To avoid hot stresses' I think it is more important to think about deposit thickness per pass. Aim to build-up coating in very thin layers (ideally around 0.0002" or 5 um), this will help in controlling distribution of heat. Ideally, try and set-up process so that spraying is continuous and that part/coating temperature remains fairly constant through out. I know, easier said then done
, but that should be your goal.