Trovenn,
I think you'll find that there is a lot of "flexibility" in the meaning of the last two digits from rod to rod, and manufacturer to manufacturer.
The last two numbers can be read together, as some instructional texts currently suggest but it doesn't offer as much accuracy as understanding what each number means.
The first two numbers of course always indicate tensile strength. In this case "70" of course is 70k psi.
The third number indicates position capability.
1 is all position
2 is horizontal and flat but varies with joint type (F or G)
3 (and you probably won't find many if any around now) is for flat only.
The last number indicates flux composition, AC/DC/Polarity, arc type, penetration and and iron powder percent (which is what makes a rod "smooth".
This number can vary a little. I am "quoting" from an older text here, but it is pretty much one of the best welding texts I have found that dates back to the 60's and 70's. Some of the rods may not be found easily any more, but at one time they existed. I can't think of any 7's or 5's right now you could find.
Last number:
0: 6010 is DC reverse, organic slag, deep pen. 6020 is AC or DC and mineral with med pen., no iron powder in flux.
1: AC or DC rev polarity, organic slag, digging arc, deep penetration, no iron powder iron powder in flux
2:AC or DC rutile slag(titanium dioxide) medium digging arc, medium penetration, 0-10% iron powder in flux
3: AC or DC Rutile slag, soft arc, light penetration 0-10% Iron powder flux
4: AC or DC, rutile slag, soft arc light penetration, 30-50% Iron powder flux
5: DC rev polarity, low hydrogen slag, medium penetraion, medium arc, no Iron powder in flux.
6: AC or DC rev. polarity, Low hydrogen slag, medium arc, medium penetration no iron powder in flux
7: AC or DC Mineral slag, soft arc, medium penetration, 50% Iron Powder
8: AC or DC rev. polarity, low hydrogen slag, medium arc, medium penetration, 30-50% iron Powder in flux.
As I said, this is my "refresher" manual I use from time to time. Admittedly it's out of date. The name of it is Welding technology, (2nd ed) , Giachino, weeks and Johnson. Publisher: ATP (American Technical Publishers) 1973. I have others, but this is my favorite because of the technical information it puts in easy to read, and access form. If a customer asks me a tech question that I can't remember, and in some cases I don't know, it's my first go to book. There are other sources, that are used in the industry like Lincoln's "bible". Sorry for the tangent. I know someone is going to question my source on this, but I put it out for all to see and look up if they have a question about it.
So to sum up the 7018, it can be used in all positions, with AC or DC+ polarity. You won't find it won't work well at all in DC-...just simply a nightmare, unless it is open root and is needed. It doesn't mean that it would be ideal in AC either...but a good AC welder, with a copper wrapped heavy core will weld it. A lighter, more modern buzzbox may not. Hence the need for the AC rating. The AC rods have a little different flux composition. It won't be the same color, as the other spent fluxes. It'll usually be charcoal black, with little sheen, and it seems to be "lighter" in weight...from my experience. It welds great on DC as well...restarts seem easier in DC too.
K0ua, I peck every rod like a chicken...just my way of doing things. I don't like scratching like a chicken to start the arc.
It's a muscle memory thing, and it gives me good starts.
