Gary, I understand your reasoning, but possibly the previous poster was making a comment based on the "Welding Metallurgy"- Linnert text. I'm going to paraphrase a little here: RG45 is ordinarily made of rimmed steel and has a composition similar to covered arc-welding electrode. Since it is a rimmed steel, continuation of the carbon-oxygen (r****ng) reaction is bound to occur whenever the steel is remelted. It is designed to melt quietly without sparking under the O/A flame and solidifies without excessive porosity. The relatively low temperature of the weld melt under the O/A flame minimizes boiling from the carbon-oxygen reaction, and the slow solidification rate allows almost complete ecape of the gaseous reaction products. "However! Woe unto the welder who uses this rimmed steel rod as a filler metal for a more rapid process such as gtaw: Excessive porosity will be his lot!" The typical RG45 composition would be 0.05% carbon, 0.2% manganese, 0.02% phosphorus, 0.03% sulfur, and 0.008% silicon.
RG60, on the other hand, has 0.08-0.16% carbon, 0.75-1.5% manganese, and
0.10-0.5% silicon. This composition would put it in the killed steel classification and the higher levels of carbon and manganese would lower the amount of dissolved oxygen and thus the r****ng action.My opinion here: RG60 sounds as if it would be o.k. for both tig and O/A useage, but RG45 sounds best used for O/A only.
Hope this is helpful,
-dseman