Hello,
As a beginner (with an AC welder), I've done a lot of reading on rods and their uses recently. For example:
https://www.weldingmania.com/stick/d...izes-and-uses/
https://weldingpros.net/stick-weldin...ts-calculator/
https://weldzone.org/welding-rods-sizes/
I'm a bit lost on a few points. Yes, I know that as a beginner I probably don't need to be this detailed in my understanding. That doesn't change my level of interest.
1: Why E6012?
E6011 handles your needs for deep penetration. E6013 works great for shallow penetration.
So, why the need for E6012? You could adjust the amperage of the others to get the desired result, right?
2: Why Iron in the coatings?
Coatings 4, 7, 8, and their respective XX2(4,7,8) counterparts, all contain Iron. Why not just use a larger rod and higher amperage for more deposition? Unless you're brazing the iron in the coating onto the welded part, you have to transfer enough heat to the rod to melt all the metal whether the metal is located in the coating or in the main rod, right?
3: When would you use different levels of coating?
Rods can be coated in flux lightly, moderately, or heavily.
I'd assume that lightly is for fresh metal, like in a factory.
Moderately is what you'd normally use.
But when would you use heavily coated rods? So far, when people deal with rust and grim, the threads I've seen online say something to the effect of, "Use 6010 and burn the contaminates to hell." Although I have no reason to doubt these recommendations from professional welders, it further weakens the case for heavily flux coated rods.
4: Why E90XX?
Most sites list the E60XX and E70XX when describing rods. But when I went to purchase rods, I couldn't help but notice that there are E90XX rods. E60XX are the common ones. E70XX have higher ductility and are tougher. But when would you use E90XX rods? What are they for? Tougher, defiantly. But most steels are not even that tough, right?