"Pitting" When MIG welding, What is it?

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sniper

Super Moderator
I was watching a program on Spike were they were making a cage for a SCCA road race mustang. A SCCA inspector came out to approve the cage and he commented that the welds looked good and there was no "Pitting", he said he has seem many cars with badly Pitted welds and had no idea how they passed inspection.


So is pitting when the welder is too hot and you think the weld is good but around it you can see where some of the surrounding material was burned off or consumed? Ill try and get some photos of what i am referring to but in the mean time, any thoughts?
 
if you atr too hot you can have basicly as you described and the area around the bead got too hot and it will look like the bead is setting in a big recess. He could also be referring to pourosity, where there are inpurities that will cause pits or pours. This type of weld is contaminated and should not be used. This can even happen when tig welding. A lot of guys will try to go back over the bad section, that will not fix it, it has to be ground out before you can weld over it.
 
Pitting reffers to the weld being pourus. as in, filled with tiny holes. the weld will fail from cracking.
Being a good welder is welding absoultely as hot in the specified range your welding specification says you can weld at, and still maintain control the weld.



abustiffy - when the toes of the weld flow below the surface of the base materials, that is undercut. Undercut is cause by too low of a travel speed (for the voltage), or incorrect torch angle. Using the classic C25 (75/25% ar-co2) mix for mild steels will virtually eliminate all, but the most sever undercutting on ferrite materials. It will also flow better, and the present oxygen (from the breakdown of the co2 gas in the arc) will help maintain the puddle flow (wetting action), along with help flatten the bead.

C25 limits you to short circuit welding. Not bad for the newbies. All position, low WSF (wire speed feed & amperage go hand in hand with mig), good for thin material.
You can use it with globular also. Alot more WSF (i.e. hotter & more material deposited), spatter. You're limited to 1F & 2F weld positions (flat & horizontal fillet welds.... T joints.)

















Most of the people on "those" shows can't weld worth a ****. They approach operator levels of, "I can tack weld".
Normally, if you see one of them that actually makes a quality weld. It's because they've got a newer machine that has pulsed transfer. Which, is the best thing ever, literally. Even grossly lowers the operator skill level.
You basically wrap almost all of the positive features from the other 3 gmaw transfer modes, add a gross cost savings on materals & the only downside is that you need a mahcine that can do it, which is alittle more initial cost.
You can always tell when they do it too. The welding will sound more like a high pitched growl instead of an arcing sound. It's a slightly lower tone.
 
As stated, pitting is impurities (sp?) comming back up through the weld material.

I have seen MIG welders on chrome molly race cages cause pitting due to overheating of the chrome molly (oxidation of the chromium in the tubing).

Typically, pitting is caused by a dirty weld surface, dirty welding wire, lack of sheilding gas or a combination of all.
 
Too much gas also ?? Or is that tig ???
I have both welders and learning...
A novice !!! Been welding to do projects for years....
 


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