Arc welding question

[Concrete B]

My welder is capable of AC, DC+ and DC-

the lead is labeled "to work" and "electrode"

we use e7018, that is not properly stored (lids on, but no dryers or anything)

The metal is always painted with this nasty gray epoxy ****, red iron, or galv. I do really well on red and galv, but this gray ****...

So anyway, My question is about the polarity of the weld. 7018 is supposed to burn on any polarity, but sometimes it sounds...wrong. I never switch to AC, but can never decide on DC+ or DC-. With "to work" grounded, and my stinger on "electrode", which setting should be used?

 

[Zrexxer]

Run 7018 on DC electrode positive.

 

[welder4956]

Absolutely! E7018 runs best on reverse polarity (DC Electrode +).

 

[rockwithjason]

i don't weld dirty metal. if there is any kind of coating on it i clean it off. i even grind off mill scale and rust where some guys dont. it makes my life so much easier

 

[cnc-me]

i don't weld dirty metal. if there is any kind of coating on it i clean it off. i even grind off mill scale and rust where some guys dont. it makes my life so much easier

You bet, that's what sand blast cabinets are for.

 

[sberry]

Yes, rod + with almost all electrodes. They often list every possible combination with rods but set it to DC+ and bust the knob off so you are not tempted to fool with it. Only time my machine ever see's AC is on occasion with nickle on cast to reduce arc blow.

 

[zmotorsports]

Same as above. Reverse polarity, electrode positive (+) and work negative (-). Also clean the metal prior to welding. A flapper disc works great. Mike.

 

[claymont]

Why not use 6010 if you're not going to clean it? You probably should be using a respirator if you're welding with those conditions. IMHO

 

[toxicz28]

Galanized should be ground off when using 7018. The zinc contaminates the weld. And, if the welds are inspected, and the base metal is not ground clean, they will be rejected. The red is a solvent based primer, the grey is epoxy. My only advice, as it was already given, grind your weldments to clean steel.

 

[Concrete B]

Well, I've been welding at work, but Im 3rd or 4th in line, so I never weld anything overly important. They don't supply grinders, and if they do they only give us cutoff wheels. If I could I'd grind everything. They also don't supply rod other than 7018. I am certified in flat fillet. I'm not a bad welder (nor an allstar), but most of the time I just need to fire up the machine and go, not set it up. Dialing it in isn't really my forte.

At home I MIG a lot, and have been scratch start TIG welding also off a hobart stickmate. I never really stick at home.

As for galv welds failing inspection, I have had many inspected and passed, and never ground a single one. I learned to stick on galv, it comes natural to me anymore, but that gray epoxy screws me up (and stinks worse than galv, IMO).

Thanks for the help guys.

 

[trexdoink]

Agree with all this and will add that a root pass with E6011 (ac) or E6010 (dc) should be used because of penetration issues with the large flux on the e7018. The 7018 it a great rod but really was designed for use on high carbon steel as a top pass and the rods are very susceptible to moisture. When i was in college welding (last century) we always did a root pass with 6010 then covered with 7018. Depending on the application you may be better of with a good all purpose rod like 6013 but it sounds like your stuck with what you got.

 

[sberry]

Millions of welds are made every day with 7018 and without root passes. When its learned its actually quite good on dirt and coatings as there is a lot of flux to carry contaminates away. Torching off epoxy and paint in the weld area works too, sometimes better than grinding as splatter really sticks to ground surfaces.

 

[REAL HOT SCHITT]

M8t!, religiously grind all "schitt" off! And use a propane torch to heat until moisture disapates....also store wire or rods in hot water cupboard.
Prior to using ?ble rods, just heat with torch for minutes without damageing coating then weld.

 

[BD1]

yes , 6010 5P [DC] is the answer for dirty,rusted, painted , or galvanized metal. best penetration ever. no cleaning required and will burn through galvanized metal. if looking for pretty weld cap with 7018 DC as stated. bob

 

[1931S/X]

using 6010 or 11 for a root is a most common with an open root joint. you can control your burnthrough and fill. if the root is not open you dont need to use 6010. 7018 has plenty of penetration on its own. the work i do 90% of the time is done with 7018 if stick welding. many times you can not fit a grinder in the joint and you might not have access to a torch. these are structural connections and are ut inspected. the recomended way is rods heated in an oven, preheat the joint and hit it with a wire wheel. but its not always feasibile or even possible and it will certify if you know what you are doing.