Black soot?

admin

I recently welded some steel and noticed a lot of black soot covering the weld and weld area. I never had this happen before. I am using a Lincoln 175 pro with .023 solid wire and a Co2 Argon mix. The spool is half gone and did not do this before. The gas is down to about 75% full and welds looked OK before. I was welding regular hot rolled to hot rolled and got the soot. I also welded some hot rolled to drill rod with the same result. The amp and wire feed are both set at about 75% max. I ground and used acetone to clean all metal that was welded. The welds seem to be fine. The black coating comes off with a wire brush. It just bothers me that this just started with no change in anything I have done. I'm sorry I don't have pics or more specifics on the metal. Any insight would be appreciated. Thanks RON
Reply:Hey Ron.I've noticed the same thing sometimes when welding certain steel items... Lincoln 175T with .023 solid wire and 100% Co2.  I don't have an answer for you - just confirmation that you are not imagining things!  Rick V
Reply:Hye Ron,A search for carbon deposit soot yeilded up an previous post...'Mig welding stainless overhead need help by Mackiman1962'Here's what was decribed in that post."There is alot of carbon when finished welding though." (mackman1962)The "carbon" or "soot" like deposit along the toes of the finished weld is primarily Manganese Oxide formed from Manganese in the stainless steel reacting in the arc. First time I saw this was in 100% Helium TIG welding of stainless, and I had the stuff analysed in a mass spectrometer. For some reason (hotter arc maybe), you get more of this with Helium shielding gas as compared to Argon.
Reply:Thanks Rick. What I thought was drill rod may have been stainless.I don't claim to know a lot about properties of metal but I know some grades of stainless do rust. This had some specks of rust on it. I guess this means I can't tell the wife I need a new welder because this one is kaput. At least not with a straight face. LOL
Reply:I'll tell you your welders kaput and you need a new one if that will help. I'll be glad to send a note...Dear Mrs Ron, Ron requires a new welder because his old one ist KAPUT! Please allow him time and funds after school to go and purchase the new welder he needs to build his thingy."              Signed. Members of Welding Web..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan