A heretical observation / question

There is a slight difference between 6010 and 6011. 6010 tends to dig a bit more. Some shops I have worked in they use 6011 on DC for their tacking. Using 6010 on an AC machine is difficult to say the least. If you have a machine that makes a square wave AC you will find that DC rods run just fine on it. Out of position you will find that the smoother arc of DC is easier. One problems with 7018 AC is that it tend to have porosity at the beginning of the arc if you do not pay attention. The days of regular sine wave AC is quickly disappearing with the more modern machines. From my own view DC is smoother and easier to use in out of position joints. I don't like 7018 AC rods and avoid them if possible. If I have an arc blow problem and I can switch a machine to square wave AC I will do it and use 7018 DC rods. Randy

Yes, I know AC limits the rod selection somewhat ... but after practicing fillet joints in class (6010 root pass / 7018 fill passes), I tried the same thing at home using 6011 root / 7018-AC fill, and got what appear to be identical results (maybe even somewhat better at home--which brings up another heretical observation: At my current level of skill, I like the discrete steps on my machine at home over the infinite control at school; I have less trouble dialing in just the right amperage right from the start). I don't know if the 7018-AC would produce equal results as far as x-ray, code-quality (certainly my welds are not quite ready for that examination!), but ... it sure does lay down a beautiful bead.

So, here's the question: What would some of the more experienced welders in this group say about the advantages of DC over AC? I have to say that, based on the instructor's comments and what I've read here and there, I expected far more difference that I have found so far.

I look forward to your responses!

I am not a more experienced welder, but here is my 2 cents anyway. With some rods, I have exactly the same experience. I can't tell any significant difference between AC and DC. But I have some rods that are worthless on AC. I can't manage to run a good bead. The arc extinguishes if I don't do every thing perfect. With DC the rods are useable ( But the flux is still a real pain to chip off ). Dan

.> With DC the rods are useable ( But the flux is

Why do you chip the flux? I put a wire brush on a grinder (wear face mask) and by by flux. Must be a reason you guys use a chip hammer?

Mac plowboy and wannbe weldor.

snipped-for-privacy@duke.edu (Andy Wakefield) wrote in news: snipped-for-privacy@posting.google.com:

Welding via AC verses DC has nothing to do with quality of weld.(ease to the operator, yes) They are just two different tools. When welding via DC current, the current is always flowing in one direction. Welding via AC, the current changes many times, oscillating between two directions, but falls to Zero, between these changes, so in the flux of AC type rods, there is an added "gaseous conductor" that keeps the arc going easily, even though it falls for a very brief moment to zero.(good welders can break the rules, they even weld with DC rods on AC!!oh God, a heretic!) This change of the current going from + to -, then - to + very quickly has it's advantages.(to the novice it is hell, as they can not keep the arc established) When "cookin/brewin" a molten puddle, this "vibration/shaking" of the puddle in the AC "zone", can allow for better "cleansing" of contaminates in the puddle, as this shakin' action helps in bringing them to the top of the puddle to escape, if the concept is used properly. As Randy mentioned earlier in the thread, AC is good for combating arc blow, as there is no magnetic field build up via AC, as the field is always collapsing/canceling/changing direction, so a strong magnetic field is not built up in the weldment. As your control/balance increases, the less meaning there is between one being "better" than the other. In DC the arc is "smoother", easier to "conquer". So what. They are two completely different tools. It's like arguing a 6 point socket is better than a 12 point socket. I doubt you'll find a mechanic worth anything, bothering to argue about one socket type being "better" than the other. So, if proper application is applied in both, (AC verses DC) you will not see a "finer weld" using DC verses AC if your competent in both. SMAW welding via DC current is just easier to "manage". Big Deal. I have welded many times with DC "ONLY" electrodes on AC. (SMAW) The point being, you have heard the "wives tale", "DC welding produces a better weld than AC" All you have found out is that it is B*****it.

Kruppt

These are some odd ball rods I bought at Boeing Surplus. The flux on these is glassy and very hard. Much worse than any other rod I have ever welded with. They are an 18-23 stainless rod. Dan

This is as good a time as any to find out if this is correct. I understand the peening action of the hammer helps remove internal stresses in the weld while removing the flux. Peening is good.

Billh