Hey Fellas, I am MIG welding a fillet joint and I am starting to get a lot of porosity (big open potholes). Any idea what I am doing wrong? I am using a Millermatic 175 (220V), running at the high end for 1/4" thick plate. Wire feed is at 60. Is my travel sped too fast? Thanks.
is the material new and good and clean? gas flow OK? I think those pockets are due to impurities in the weld bead.
I am no expert welder, but do plenty of welding here at work. Check your gas. May be restricted. Iwould slow your wire speed down to 50. Don't know if it help out.
Thanks Guys, I'll do both.. Slow my travel speed and increase gas flow from 30 to 40 cfh. This is just mild steel, 1/4 thick
Probably the best piece of advice I was told when I bought my first mig was "if the weld sounds like bacon sizzling in a pan, the wire speed and volt/amps is about right." Is the plate clean and free of rust,paint and oil etc at the weld joint? Check polarity....cables correct Is the gas on? Pressure right? hasn't run out? Also remember you cannot do good mig welds outside in the wind unless you use flux cored wire. couple of useful things from the miller site. http://www.millerwelds.com/education/tech_articles/articles8.php or http://www.millerwelds.com/pdf/OperatorsHandbook.pdf
The pictures that you have posted look like you are working outside? Wind will fuck up a weld, your sheilding gas goes away.
Make sure all surfaces are clean and gas is flowing at approx. 25 cfm. If those both check out ok, try slowing it down a bit.
i just finished welding school so I should be able to help you with any welding questions you may have...but it sounds like everyone took care of the obvious reasons for porosity. Another one may be the wrong gas combo.. I like 75% 25% combination it is a good all purpose combonation but there also different gas mixtures for thicker and thinner steel. Good luck any ?'s give me a shout bob
One thing to consider is that when you are doing an inside corner fillet (not sure if that's what you're doing) you can sometimes easily be using TOO MUCH gas pressure. This will give porous looking results as a result of the pressure blowing too hard INTO your puddle. An easy way to determine proper gas flow is to START with the gas LOW - keep turning it down until you see the porosity occur then go back up enough to give you a little "cushion". This will do 2 things first it shows you EXACTLY what a LOSS OF SHIELDING GAS looks like (allowing you to immediately recognize it next time) and second it shows you just how LOW you can go - with a given set of conditions - keep in mind welding a INSIDE FILLET versus a OUTSIDE CORNER versus a FLAT LAP etc. etc. etc. will ideally require a slightly different setting - usually one finds a happy medium that works in all positions and then ignores the gage, but all guages can potentially read differently and as already mentioned your surrounding conditions also can have an effect - how windy is it?? How clogged is you nozzle??? How accurate is your guage??? It can all add up to bite you in the rear sometimes. One time while TIG welding my welds were suddenly looking like shit - nothing I did made them any better - only explanation was that I had instantly forgotten how to weld!!!!! Well after a closer inspection I discovered that my shielding gas hose had loosened up and was now sucking in a little air - porosity city despite what the flowmeter said. Tightened it up and suddenly I could weld again. SHIT happens I guess.
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