I agree with hold. Section IV will list this material as unlisted and you will need to have a weld procedure for all base materials being welded to the AR400. The filer materials can be E71T-1X (CO2 or AR/CO2 would work) just depends on the thickness of material to what gas mix i would use. CO2 will require more arc voltage to compensate for the lack of argon and is very deep penetrating.C25 will require typically 2-4 less arc volts at the same WFS as CO2 so the overall heat input into the material is greatly reduced. ER70S-6 will also work in this case with spray transfer or pulsed spray transfer. I would just pay attention to HAZ hardness issues, pre-heating will slow the cooling rate and prevent the quenching effect on the BM.
Hope this helps.
