Welding porosity question

[Lance-W]

Every once in a while I get a weld that has "porosity" in it.  Both parts in the picture are clean.  The gas (75-25) is on.  There is no wind.  I'm using the cheap Harbor Freight (.030) wire?  The weld on the right was done immediately after the one on the left and no porosity? I do use a splatter spray but both sides had it on it.  Sometimes it goes as far as growing a "bubble" in it, kinda like a lava bubble.  Only thing I can think of is contamination but I can't figure out where it's coming from.....  Anybody got any ideas? 

[Punkur67]

Prob a gas flow issue. Could have a pinch in the hose or a loose connection.

[Doug Heim]

What he said...

I get that every once in awhile. Mine is caused by too much build up in the nozzle. I do use tip dip but sometimes Im just moving along so quickly to notice the build up untill I have that same look in the weld.
Just grind the weld out and reweld (duh). I dont advise trying to weld over it to "burn it in" and make it look good. In most cases all that does is sends you chasing it and then there is more to grind.

[Lance-W]

I really don't think it's a gas flow issue.  I checked the nozzle and it wasn't obstructed.  It wasn't spotless but far from blocked.  The hose is never in a kinked situation.  I really can't buy the gas flow issue.  Anything else cause this that you guys can think of?

Plus duh every once in a while I forget to turn the gas on and it's nothing like that..............

[Icky]

When you say clean do you mean free of grease dirt and all that stuff? Or do you mean you grinded the mill scale off of your metal? I know there has been debate about whether you need to or not, but your contamanation could be coming from that if you leave it on. I always take it of even if it's just the thin coatiing on Cro-mo or DOM. I've never used wire from Harbor freight, maybe someone else will chim in about that. There also could be contamination on your wire depending on how old it is, or condition it's in

[Lance-W]

A couple of the parts (not the one in the picture) were recently sandblasted.  Doesn't get much cleaner than that!  The wire isn't that old.  Maybe 2 months old and I live in dry SoCal where it'd stay clean.  Good thoughts.  Basically along the line of the contaminates but not THE contaminate.

[Lance-W]

On second thought that is one of the sandblasted parts.  I just went out and checked.  So it was clean.

[Icky]

Sand blasted huh, thats way to high tech for me  I usually use a 3m pad made for a 4 inch grinder. Maybe try switching to a high quality wire from AirGas or Praxair or something like that and see if the problem continues. I know on our wire feeds at work, we usually have a piece of scotch brite (red) zip tied around the wire as it comes off the spool. It cleans off the wire before it goes into the gun, but then again we rarely use them and they get stored in some mess up areas sometimes. Your gas could also be to high of a pressure, to where it's sucking air back in your nozzle or something like that i'm sure someone will explain better then me.

[artie on edge]

Hi Lance, this is one of the things that my recent lesson eliminated from my welding as well.

My problem was EXCESS gas flow which can, when the job and the torch are at the right angle suck air into the weld pool, creating exactly what you are showing (gas speed was too high).

Mine is now set at between 12 to 15 LPM sorry Litres Per Minute..Im not sure what measure you guys use over that side of the ditch. It was an occasional problem as the torch and the job had to be at the 'necessary' angle to create the venturi effect to draw the air in.

[fabr]

What he said...

I get that every once in awhile. Mine is caused by too much build up in the nozzle. I do use tip dip but sometimes Im just moving along so quickly to notice the build up untill I have that same look in the weld.
Just grind the weld out and reweld (duh). I dont advise trying to weld over it to "burn it in" and make it look good. In most cases all that does is sends you chasing it and then there is more to grind.

Ditto to that.

[fabr]

A couple of the parts (not the one in the picture) were recently sandblasted.  Doesn't get much cleaner than that!  The wire isn't that old.  Maybe 2 months old and I live in dry SoCal where it'd stay clean.  Good thoughts.  Basically along the line of the contaminates but not THE contaminate.

Actually I have found that sand or glass bead blasting can cause just that problem.i only grind with a flap wheel now. i get the same thing on some welds and also wish i had the answer. on cromo I rarely do any prep tho other than a wipedown.

[fabr]

Hi Lance, this is one of the things that my recent lesson eliminated from my welding as well.

My problem was EXCESS gas flow which can, when the job and the torch are at the right angle suck air into the weld pool, creating exactly what you are showing (gas speed was too high).

Mine is now set at between 12 to 15 LPM sorry Litres Per Minute..Im not sure what measure you guys use over that side of the ditch. It was an occasional problem as the torch and the job had to be at the 'necessary' angle to create the venturi effect to draw the air in.

I think that has possibly been my problem also. Question,is it possible to have a small diameter cup on the TIG torch and at higher amps be able to "heat or -boil?- the gas " off the weld puddle?

[Rick S.]

I think the problem is the sandblasting and the waterjeted gussets.
Sand blasting impregnates the steel with glass and so does a waterjet.
Anytime you're using waterjeted or sandblasted parts you need to grind or sand everywhere you plan to weld.

[Doug Heim]

Must be the sand blast. Those gussets were laser cut. That brings up another point though...  I have heard of the plasma edge becoming a problem on laser parts but never expierenced it. I have heard of the problem existing more in TIG welding though.

[Reidy02]

Mine turned out OK! But then again I think I did grind mine B4 welding!