Mig spray Porosity

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Since I am giving credit for these questions as to their source being Ed Craig welding books, my assumption that it is not going to be a problem."You have a lot of porosity in your carbon steel Mig spray welds. Select three changes that will decrease the porosity.[a] increase weld travel speed[b] reduce weld travel speed[c] use larger diameter wire[d] increase current[e] decrease voltage[f] increase voltage[g] decrease weld size"after a long day of doing nothing...its gooood to kick back" Pumbaa
Reply:good question...wish I knew the answer
Reply:I had the credit issue with the AWS master chart of welding and allied processes.  In their case I had to not only give them credit but as to where the information came from and they were happy.Common sense in an uncommon degree is what the world calls wisdom.
Reply:I have never been able to pin down the why of porosity in spray arc. I have welded for hours, with perfect welds, then all of a sudden....swiss cheese! For no reason whatsoever! I stop and lots of times I can weld it right up by just going back over it, then others...more swiss cheese. No change in parameters or atmospheric environment...it just happens! So when some tells me what to do to stop it, I just say OK, and keep on going. I've already been there and done that.  The usual suspects would be, dirt, oil, loss of gas, wind, bad wire, mill scale, and so on. Keep your carbon arc handy.Experience is the sum of our mistakes.  Arcin' and Sparkin' Rocky D
Reply:Rocky, you think maybe it could be due to annomolys in the base metal?  There has been some discussino among the blacksmiths lately relative to differences encountered in the same bar of steel, and poor quality control from the mill.This has been determined to be the reason for a lot of problems encountered with bending as well.Appreciation Gains You Recognition-
Reply:I think it has to do with how the planet's line up.  I'll be the LAST one to let you down !
Reply:Dang!, I knew I should have ask the question 5 years ago as to why I would get them perforated looking welds every now and then. I guess that my guess was pretty good; that the pos. flow was overlapping into the neg. & therefore trying to create some kind of AC mode. Or maybe my flowmeter sucked in some air?Good subject, if anyone ever finds out the real problem, please post the answer.
Reply:Originally posted by Franz Rocky, you think maybe it could be due to annomolys in the base metal?  There has been some discussino among the blacksmiths lately relative to differences encountered in the same bar of steel, and poor quality control from the mill.This has been determined to be the reason for a lot of problems encountered with bending as well.
Reply:Rocky, perhaps there was a magnetic inclusion in the base metal, the initial pass would destroy the magnetic propertys, and enable you to weld over it.In the case of having to gouge it out, I'd tend to think there was a problem in the base metal.Unfortunately, we never have the instrumentation to make these determinations.Appreciation Gains You Recognition-
Reply:Originally posted by Franz Rocky, perhaps there was a magnetic inclusion in the base metal, the initial pass would destroy the magnetic propertys, and enable you to weld over it.In the case of having to gouge it out, I'd tend to think there was a problem in the base metal.Unfortunately, we never have the instrumentation to make these determinations.
Reply:Comon now Rocky, you can't go blamin the wife's cat Gremlin for bad deposits, he ain't even allowed in the shop.Appreciation Gains You Recognition-