Color of steel tig weld

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I've been tig welding for about 3 years or so, and feel like I'm a pretty decent at it. My question is more steered towards welding mild steel and chromoly with ER-70S filler. Sometime my welds turn out almost like a salmon color (kinda like tig welding stainless steel) and other time its just a gray color. Sometimes this would happen even on the same piece (not one weld but say I would do the back side of a plate or something and one side is salmon colored and the other grey). After you wire brush off both of them though they both look exactly the same, no undercutting or cold welds on neither. Here's a couple projects that I've welded up in the past to show you where I'm at skill wise. I'm more oriented into the sports car area, having built 2 tube chassis cars, built 2 gas tanks made out of 1/32 aluminum with no leaks first time weld and very minimal warping in the sheet metal, thats where I'm at skill wise atleast.The machine that I use is a miller synchrowave 200, I try to stay with 1.5% Lanthanated tungsten as its a well rounded one, and if its not that I use 2% thoriated. Input in greatly appreciated! Attached Images
Reply:Pic #1...Yup that's what steel looks like..The exhaust pics..I suspect the material is STAINLESS hence the difference in colors..You weld the exhaust with 70S????...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:First picture is actually an aluminum part ... As for tig welding the stainless steel exhaust that was done with a 308 filler and not 70S. Neither of those pictures are of what I was talking about. I just uploaded those pictures to show that I'm not very inconsistent with my welding and trying to hopefully rule that out of the equation.And before anyone says anything about me stacking dimes with aluminum, I personally don't like that look and just much rather like the closely stacked welds. I have done the stacked dimes for a few guys that I know because I know thats what they like (like 80% of the rest of the world) but I'm also aware that it makes no difference in strength of the weld what so ever. Its more of a signature in style of welding.Last edited by dj55b; 05-10-2011 at 04:11 PM.
Reply:Well you got me on the Aluminum although after a second look I was going to ask about it..The "Skillset" is just fine....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Would something like slight variation in torch angle, make the color of steel look different while welding. Because the only thing I've ever noticed is when particularly tig welding chromoly, when I hold the torch at the end and wait the few second for the post flow gas to go by. When the gas stops you can see a bit of a color change in there. Also If my bead is still mostly grey to begin with, the last part of it (last bead) is usually still salmon in color. I'll most likely be welding up some more of those chromoly tubing later on tonight so I'll shoot some pictures over with a proper example if it happens again.
Reply:Salmon color of stainless steel is sometimes known as :"heat tint".  Its debatable if this is bad.  My understanding that in sanitary situations (food processing, drinking water etc.) it needs to be removed.  See pickling solutions - nitric acid.  Apparently straw coloration is OK.Polishing will also remove it.  A nice clean stainless surface is consider to be the "passive state" which will allow a thin layer of chromium oxide to form and it will then be rust resistant.On mild steel, the only redish looking think I ever see looks a lot more like rust and is typically my fault for not purging the lines long enough.  I wouldn't call that color salmon, I would call it red and it looks like it was dusted on (maybe primer red).  Its usually pretty obvious where I goofed.Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:Originally Posted by con_fuse9Salmon color of stainless steel is sometimes known as :"heat tint".  Its debatable if this is bad.  My understanding that in sanitary situations (food processing, drinking water etc.) it needs to be removed.  See pickling solutions - nitric acid.  Apparently straw coloration is OK.Polishing will also remove it.  A nice clean stainless surface is consider to be the "passive state" which will allow a thin layer of chromium oxide to form and it will then be rust resistant.On mild steel, the only redish looking think I ever see looks a lot more like rust and is typically my fault for not purging the lines long enough.  I wouldn't call that color salmon, I would call it red and it looks like it was dusted on (maybe primer red).  Its usually pretty obvious where I goofed.
Reply:What's the purpose of that screen on tail pipe you have pictured?
Reply:That part is a silencer. I only use it on the streets, It has 2 bolts holding it through the bottom. Here's a picture of it all polished up. I've also attached pictures of the car in question is anyone care  Attached Images
Reply:Originally Posted by dj55bI know what you're talking about as far as that "primer red" is, but no, what I'm referring to looks almost like stainless steel. Found a picture of what I'm talking about.And no, not using a stainless filler by mistake.
Reply:TIG weld and HAZ color is totally dependant on the degree of inert shielding present at the time when the weldment is hot enough to react wtih oxygen, nitrogen, oils, and other contaminants.  With clean material and an inert enviroment, there is no discoloration due to welding.  Zero discoloration can be achieved when welding within a glovebox with O2 and H2O less than about 20 parts per million (ppm).  Extra shielding such as trailing shields can provide enough protection from oxidation, and nitride formation, etc. that causes discoloration.  A relatively small weld on thick materil can remain free of discoloration due to the rapid cooling rate and presence of adequate shielding.
Reply:Originally Posted by pulserTIG weld and HAZ color is totally dependant on the degree of inert shielding present at the time when the weldment is hot enough to react wtih oxygen, nitrogen, oils, and other contaminants.  With clean material and an inert enviroment, there is no discoloration due to welding.  Zero discoloration can be achieved when welding within a glovebox with O2 and H2O less than about 20 parts per million (ppm).  Extra shielding such as trailing shields can provide enough protection from oxidation, and nitride formation, etc. that causes discoloration.  A relatively small weld on thick materil can remain free of discoloration due to the rapid cooling rate and presence of adequate shielding.
Reply:It isn't necessary to remove the copper coating on TIG wire, although some folks do.
Reply:Where are you located dj55?  Lots of those cars look familiar. For smaller parts there is nothing like a gas chamber for clean welds. For big parts that must have nice welds just weld small sections at a time and post purge them.  Normally anything mild steel though especially on a car is painted afterwords.
Reply:When welding stainless, the grey color weld is due to overheating the weld zone. The grey you see is caused by something called "carbon precipitation", which creates less than optimum conditions in the weld and the surrounding area.
Reply:Originally Posted by ElectricSquidWhen welding stainless, the grey color weld is due to overheating the weld zone. The grey you see is caused by something called "carbon precipitation", which creates less than optimum conditions in the weld and the surrounding area.
Reply:Originally Posted by VPTWhere are you located dj55?  Lots of those cars look familiar. For smaller parts there is nothing like a gas chamber for clean welds. For big parts that must have nice welds just weld small sections at a time and post purge them.  Normally anything mild steel though especially on a car is painted afterwords.
Reply:Originally Posted by ElectricSquidWhen welding stainless, the grey color weld is due to overheating the weld zone. The grey you see is caused by something called "carbon precipitation", which creates less than optimum conditions in the weld and the surrounding area.