Problem with MAG

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I'm a newbie and i would like to ask if there is any solution to this problem. Weld in picture has a glassy surface on the end of the weld. Welding current was 120A. This occour when welding different materials. When i paint this part (glassy part) the paint does not stick on the surface. Is there any way to avoid this kind of surface with MAG?Sorry if something similar was already posted.Thanks. Attached Images
Reply:Just chip a little bit before you paint. Slag is a normal occurance
Reply:Thanks, but is there any way to avoid occurance of slag?
Reply:Not really.  Cleaning the surface will help.  Putting a cleaning pad on the wire as it rolls off the spool will help to.  Some small amounts slag can come from rust preventers on the wire.  But most slag in the mig process comes from the impurities/additives in the metals (at least that is the way I understand it).  You could use a wire with less silica.  You could tig, but even then you will occasionally have inpurities or contamination in the metal form slag on the surface.  Mig is pretty much the cleanest automated welding process, and I would consider the weld in the picture above to be fairly clean.Last edited by smithboy; 10-26-2005 at 09:16 AM.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Small islands of silica is normal.  If you intend to paint you should power wire brush the surface, wipe clean with paint thinner, prime , then paint.  Better yet is to sand blast.  Don't expect paint to stick to metal that has not been prepared.
Reply:What is MAG?
Reply:MIG welding used to be called "MAG" welding or MIG/MAG welding.-Heath
Reply:MIG  metal inert gasMAG  metal active gas  Carbon dioxide is considered an active gas as opposed to argon which is inert.
Reply:Ah, interesting...
Reply:I could be wrong on this, but doesn't an S-6 wire have more silicon in it than an S-2 or S-3? And isn't that "glassy" slag at the end of the weld the silicon coming out?  Are you using an S-6 Wire?  Anyone else weigh in on this?
Reply:I like the AWS process acronyms, personally, but if I use 'em, it just seems pedantic.  GMAW!See?  Pedantic.S-6 does in fact have high silicon and manganese for the purpose of deoxidizing material that's less than perfectly clean.  I believe it also wets out better than S-3.  The glassy slag is silicon coming out of solution with the molten metal.  The fact that it's not perfectly clear seems to indicate to me that it has done it's job as a deoxidizer, so that may be a good thing.  I'd have to check out the chemistry a bit more to be certain.-Heath
Reply:I like 'um to...cause in the south MAW is a word that gets used a lot.  I am just dissapointed that FCAW is not FCMAW.  Maybe they were just worried how folks might say that as a word.......Smithboy...if it ain't broke, you ain't tryin'.