TIG filler for O/A welding?

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Can I use ER70-S2 and/or S6 tig filler rods for oxy-acet welding of steel?Reason I ask is, I understand there are fillers used for gas welding that are no good for TIG.Is the reverse also true? Are TIG fillers no good for gas welding?
Reply:ER70 wire is perfectly acceptable for O/A welding.Have we all gone mad?
Reply:Some sources suggest 70-S-6 as preferred for oxy-acetylene welding, less sparking.  The same sources suggest that it is a little softer, so perhaps better for hammer and dolly work in auto body work.   (Or perhaps it is just that OA results in more malleable welds than TIG, which I think is the belief of the Tinman).RichardSculptures in copper and other metalshttp://www.fergusonsculpture.comSyncrowave 200 Millermatic 211Readywelder spoolgunHypertherm 600 plasma cutterThermal Arc GMS300 Victor OA torchHomemade Blacksmith propane forge
Reply:I thought wire hangers were the preferred filler.
Reply:You certainly can use tig fillers or even mig wire for super thin stuff. However the rg45 takes the cake in smoothness. Even on higher strength steels and chromoly the rg45 seems to be adequate. Usually in testing the parent metal fails before the weld. You get enough mixing of parent and filler metals in the puddle to make a good weld.Millermatic 252Lincoln 175 plusTA 185tswTA 161stlhypertherm pmax 45Victor torchHenrob torchAn S10 for each day of the week
Reply:Thanks, guys.
Reply:Originally Posted by S obsessed Usually in testing the parent metal fails before the weld. You get enough mixing of parent and filler metals in the puddle to make a good weld.
Reply:Originally Posted by sn0border88You're right, thats because due to the very high heat input of O/A welding the material generally cools too slow to form enough martensite to retain the same toughness as it had in its pre-welded condition.  Slower cooling forms coarse grains and pearlite which is softer and much more ductile, which is why it fails first.Point I'm making is just because the parent metal fails first, doesnt make it a good thing.  If your filler metal severely under matches the base, but the base is still failing first in the HAZ then you know there is a problem somewhere.
Reply:Originally Posted by makoman1860Ahhhh I beg to differ on a few of these points. If you are talking about a common martensitic steel than reguardless of the welding process there will be martensite, pearlite, and austenite in the HAZ. Yes the grain structure is typically larger in an OA weld, however this does not directly imply any strength reduction. Undermatching filler is fine provided there is plenty of weld area and can actually have benefit. As for fillers I suggest the RG series, as ER series fillers have elements not needed in the OA process and tend to act sluggish. However there is no technical reason to not use ER70 fillers.
Reply:Originally Posted by sn0border88I agree completely, I think we are making two separate points here.  My point was simply that a failure in the parent metal can occasionally point to an issue with the welding process.  If, for example, you have a 4340 steel welded with the O/A process and in a tensile pull it fails 1.5" outside of the joint, you know that you are severely weakening the parent material and should look at PWHT or use of a lower heat input process.