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  • Help with tiging stainless steel.

    I'm a self taught tig welder, started about 8 months ago. I only tig weld maybe one project a month so I don't have that much time under the hood as I just do it as a hobby making some intakes, manifolds and such.

    I know that rainbow colored welds with stainless steel don't necessary mean they're done correctly but since I'm making manifolds and downpipes I'd like that quality finish.

    My issue is when I weld stainless steel and do not use filler rod the welds look good and "colorful". However as soon as I try adding filler rod the welds are gray.

    I even went as far as purchasing a pyrex gas lens saver to ensure better gas flow and to help with visibility. From all my reading I thought my issue was caused by pulling the filler rod out to far away from the gas, but I tried row after row of welds tonight with the new gas lens focusing on just that and it's the same each time. Great looking with no filler rod, gray as soon as I start adding filler.

    I seem to have no issues welding aluminum but this last part of welding stainless has got me stumped.

    I want to try and figure this out before I weld up my manifold. Plans are to pull each runner apart, clean it all up and back purge. So some nice looking welds would be nice.



    Thanks

  • #2
    Got any pictures of your practice welds? Along with the settings you're using on the machine? Sounds like you may just be too hot but some background info would be helpful.
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    • #3
      What filler rod are you using?

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      • #4
        Usually the problem is the gas coverage, when you add filler it disrupts the flow somewhat. An orbital weld which has complete gas coverage untill the weld is cool will have a nice gold appearance on a 100% penetration weld.
        Try keeping the filler in contact with the base metal, not removing it from the gas flow. The pyrex cups I have heard of, but are they gas lens types? Gas lens collets and cups are larger in diameter, but do give better gas coverage.

        Stainles needs some stainless wire brushing after welding (while still warm) to get the silver color back, if they are brown looking, one of the 3m nylon wheels will clean it up.

        I havent seen a stainless weld that doesnt have some color to it if its 100% penetration, even the inside purged one will have a gold tint to it, and the gas coverage is usually much better on the inside weld.

        Some pictures as mentioned in an above post would be helpful too.
        mike sr

        Comment


        • #5
          You have a good fit on those pipes..Fit up a sample and weld it up and take some pictures...from your description, it sounds like you are using too much heat, but that is only a guess without seeing a weld.....
          Those fittings look like handrail elbows....What gauge? Neat looking long runner intake...Is that for a turbo'd engine?
          Last edited by bayweld; 02-03-2011, 08:44 AM.

          Comment


          • #6
            If you have been welding a bunch of aluminum you are most likely moving too fast and using too much heat now that you are welding stainless. I have found you need to be using just enough heat to make a puddle after a couple seconds. It is hard to describe but aluminum is very forgiving to the amount of heat you put into it. But with stainless you need to be on the edge of enough and not enough.

            What are your current settings and what is the thickness of the material?

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            • #7
              Color changes in stainless steel are indications that one or more of three factors are not quite right. Heat input, gas coverage, or travel speed are the main factors that affect the color of your stainless steel weld bead.

              -Heat input - If stainless is anything but a shiny silver color it means that the material has been exposed to temperatures above 540 degrees F. without proper gas shielding coverage. At this point the material will begin to turn a yellowish color. As the material outside of the shielded zone reaches higher temperatures the weld bead will become darker in color. Typical color order (lower temp. to higher temp.) is light yellow, yellow, salmon, reddish, purple, blue, and then grey. Once the material has reached the grayish color the corrosion resistance properties of the material are pretty much non-existent. Obviously the welding amperage is the main factor affecting overall heat input. If your bead is a grayish color the amperage is a good place to start adjusting. Another thing that will affect your heat input is your arc length. Your arc is shaped like a cone. If your arc length is long the puddle will be larger than if the arc length is held tight. A larger weld pool means a need for better gas shielding.

              -Gas Coverage – Any time you are welding stainless steel proper gas coverage is essential. As mentioned above, the material needs to be shielded until it reaches an acceptable temperature. This does not mean that your gas flow needs to be set higher to get better coverage (your gas flow should be set between about 12-15 CFH or about 20 PSI). Setting your shielding flow too high will actually cause turbulence in the arc zone, cause your arc to wander, and potentially suck outside contaminants (ex – Oxygen, Hydrogen) into the shielded area. Having your gas flow set too high can cause worse contamination than just a grayish color. Something that is often overlooked is proper coverage at the end of your weld. When you are finished with a bead, and you crater out, leave the TIG torch at the end of the weld until the post flow stops (post flow should be about 1 second post-flow per 10 amps of welding current). This will ensure that you are getting proper coverage at the crater of your weld. Try an experiment... Make a spot weld for about 3-5 seconds on that material and hold the torch in place after you stop welding until the post flow stops. Your spot weld should be nice and shiny, and probably a yellowish/salmon red color. If you do the same spot weld and pull the torch away right after you stop welding you most likely have a gray contaminated spot weld. This is just basically showing how critical it is to maintain proper shielding.
              No Gas Lens
              http://i45.photobucket.com/albums/f1...ogaslens-1.jpg
              <a href="http://s45.photobucket.com/albums/f100/kermienut/?action=view&amp;current=Shieldingflownogaslens-1.jpg" target="_blank"><img src="http://i45.photobucket.com/albums/f100/kermienut/Shieldingflownogaslens-1.jpg" border="0" alt="no gas lens"></a>
              With a Gas Lens
              http://i45.photobucket.com/albums/f1...lowgaslens.jpg
              <a href="http://s45.photobucket.com/albums/f100/kermienut/?action=view&amp;current=Shieldingflownogaslens-1.jpg" target="_blank"><img src="http://i45.photobucket.com/albums/f100/kermienut/Shieldingflownogaslens-1.jpg" border="0" alt="no gas lens"></a>

              -Travel Speed - Slower travel speeds will increase heat input, widen your heat affected zone (HAZ), and increase the temperature of the part after it is welded. The more heat you put into a weld joint, the more gas shielding is required for the weld area. If you travel too slow, the area that you just finished welding is so hot that you are not going be able to provide enough shielding coverage to reach the material temperatures that we talked about above.
              Here are some things that you can try to help out in your situation –
              Use the smallest tungsten size you can for the best arc control. I would also use the smallest filler that you can get away with. If you use filler material that is too large it takes too much amperage to melt the filler which means that the area where you are placing the filler is too hot.

              -Other Thoughts - Some people achieve better gas coverage by using a slightly larger diameter cup, or by using a gas lens. A gas lens will definitely make your flow of shielding gas more consistent and provide better coverage. Gas lenses are a beautiful thing but not a necessity! The picture below shows the difference between gas flows that the two provide. Obviously the gas lens provides more consistent flow.
              If you increase your travel speed you reduce heat input in the area near the bead. This means that the gas coverage is not needed for such a long period of time due to the material’s temperature being lower, It will also reduce distortion while welding on thinner material.
              Any of the points made above will help on Stainless, Titanium, Inconel, or pretty much any other material that can be welded. The same basic concepts also apply to Aluminum and magnesium.
              Last edited by Miller B. Hemmert; 02-03-2011, 10:16 AM.
              Brad Hemmert
              Welding Engineer - TIG Commercial Products

              [email protected]

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              • #8
                edit--Took me so long to type this that Miller's engineer answered. I think we are saying the same thing. I defer to him if there is doubt --edit

                Originally posted by Jeebus View Post
                I know that rainbow colored welds with stainless steel don't necessary mean they're done correctly but since I'm making manifolds and downpipes I'd like that quality finish.
                The proper color is most often described as either 'straw' (gold) or 'salmon' (kind of a redish pink).

                When you see gray on the outside of the weld, it is usually because the area was overheated.

                I had the same issue - fusion weld just fine, but sometimes the gaps got to big and where I added filler it turned gray. I blamed the filler. I was wrong.

                You don't mention what you are using for shielding on the back side. Full penetration stainless requires the back side to be protected as well. Ideally a purge by argon (probably the cheapest inert gas to use).

                What often happens is when you go to use a filler rod, you end up making the puddle wider, thus more penetration. End result the back side of the weld looks like crap and the front not much better. The back side will actually have 'buggers' on it - hard deposits of carbide precipitation.

                So there are a couple of things you can do.
                1) Buy either a second argon bottle + flow meter and back purge the pipes (use lots of masking tape to hold the gas in) or buy a dual output flow meter(about $150 for a Smith one).
                2) Try using Solar Flux. A small can will set you back $50 and you need to coat it on relatively carefully. The flux reacts with carbon keeping the carbon from reacting with the chromium. Carbon as in carbon dioxide - commonly found in air. I never had much luck with it. I could easily have used it incorrectly though.
                3) From the picture you showed, the fitup is a bit too loose for this but.... It looks like you are using thicker wall pipe. Thick enough that you have a bevel on it. Rather than welding the pipe in one pass, make the first pass fussion weld without filler. If the penetration is low enough, the back side won't get contaminated with carbon and the weld will still have straw color. Now go back and make a second (or even third) pass with filler wire to build the bead. Note - this is not a full penetration weld (at least for pipes like this) and I suspect it ultimately will be a weak spot on that exhaust. However, I think mechanically its all overkill anyway - even if the turbo weigh 100lbs. On the inside of the tube there will be a narrow slit still exposed.

                If your fitup isn't perfect, with the fusion you will have some larger gaps that will need filler, these will be gray without some back shielding.

                Since you are welding on thicker wall stainless, this probably doesn't apply. Consider using smaller filler rod. On 16 gauge (just a bit less than .060 thick) using 1/16 filler means you need a puddle something like 3/16" wide (at least I do) that would be full penetrating and all the bad things as mentioned above.
                Try .035 filler. From what I can tell most LWS don't carry .035 in cut lengths, but you can get .035 in a spool for MIG. Same stuff.

                BTW, if you really want the weld too look good for a long period of time, you will have to polish or passivate it. Either will take that straw color away. Stainless works because the chromium oxidizes into a very very thin, see-through layer. You need to give the chromium a surface on which it can oxidize.
                Last edited by con_fuse9; 02-03-2011, 10:22 AM.
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                • #9
                  Originally posted by Jeebus View Post
                  I know that rainbow colored welds with stainless steel don't necessary mean they're done correctly but since I'm making manifolds and downpipes I'd like that quality finish.
                  The proper color is most often described as either 'straw' (gold) or 'salmon' (kind of a redish pink).

                  When you see gray on the outside of the weld, it is usually because the area was overheated.

                  I had the same issue - fusion weld just fine, but sometimes the gaps got to big and where I added filler it turned gray. I blamed the filler. I was wrong.

                  You don't mention what you are using for shielding on the back side. Full penetration stainless requires the back side to be protected as well. Ideally a purge by argon (probably the cheapest inert gas to use).

                  What often happens is when you go to use a filler rod, you end up making the puddle wider, thus more penetration. End result the back side of the weld looks like crap and the front not much better. The back side will actually have 'buggers' on it - hard deposits of carbide precipitation.

                  So there are a couple of things you can do.
                  1) Buy either a second argon bottle + flow meter and back purge the pipes (use lots of masking tape to hold the gas in) or buy a dual output flow meter(about $150 for a Smith one).
                  2) Try using Solar Flux. A small can will set you back $50 and you need to coat it on relatively carefully. The flux reacts with carbon keeping the carbon from reacting with the chromium. Carbon as in carbon dioxide - commonly found in air. I never had much luck with it. I could easily have used it incorrectly though.
                  3) From the picture you showed, the fitup is a bit too loose for this but.... It looks like you are using thicker wall pipe. Thick enough that you have a bevel on it. Rather than welding the pipe in one pass, make the first pass fussion weld without filler. If the penetration is low enough, the back side won't get contaminated with carbon and the weld will still have straw color. Now go back and make a second (or even third) pass with filler wire to build the bead. Note - this is not a full penetration weld (at least for pipes like this) and I suspect it ultimately will be a weak spot on that exhaust. However, I think mechanically its all overkill anyway - even if the turbo weigh 100lbs. On the inside of the tube there will be a narrow slit still exposed.

                  If your fitup isn't perfect, with the fusion you will have some larger gaps that will need filler, these will be gray without some back shielding.

                  Since you are welding on thicker wall stainless, this probably doesn't apply. Consider using smaller filler rod. On 16 gauge (just a bit less than .060 thick) using 1/16 filler means you need a puddle something like 3/16" wide (at least I do) that would be full penetrating and all the bad things as mentioned above.
                  Try .035 filler. From what I can tell most LWS don't carry .035 in cut lengths, but you can get .035 in a spool for MIG. Same stuff.

                  BTW, if you really want the weld too look good for a long period of time, you will have to polish or passivate it. Either will take that straw color away. Stainless works because the chromium oxidizes into a very very thin, see-through layer. You need to give the chromium a surface on which it can oxidize.
                  Con Fuse!
                  Miller Dynasty 350
                  Millermatic 350P
                  -Spoolmatic 30A

                  Hypertherm PowerMax 1000G3
                  Miller Multimatic 200 - awesome portable MIG (and stick and TIG)
                  Miller Maxstar 200DX - portable TIG and stick

                  Comment


                  • #10
                    Very useful post. I'm about ready to start some stainless headers for a CJ5 project. Thank you all.
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                    • #11
                      You guys ought to chip in and buy me a new Tig machine.

                      Comment


                      • #12
                        Wow, thanks for all the great info guys... seriously appreciated. I've tried half of the things that have been mentioned here but there are a few more things listed for me to try. Remember without filler rod I can get good penetration and color, and without changing a thing as soon as I start to add filler rod, bye bye color.

                        I'm going to try a few of these additional suggestion tonight and I will report back later on this evening with all the answers to your questions and some pics to help you/me out.

                        I've only tig'd some exhaust and some intercooler piping thus far with stainless so I haven't cared to much how "pretty" it was. I'm asking because I want to try and weld that manifold up half decent. In the end it's mine and it will be getting wrapped so it's not crucial, but I figured since I spent all the money and time on the flanges that I'd try and make it the best I can. It will be getting back purged as well, I have two regulators and just picked up my argon Tee this week to do it. However I don't want to start welding it solid until I get a better handle on SS.

                        As for the questions about the manifold specifically.. yes it's for a turbo'd car. My old Rabbit... lol. Currently has 367whp... but I'm shooting for a bit more power with some of this new gear.


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                        • #13
                          Alright I tried it again... this time with a bit more success.

                          Here's all the info I think you guys would require.

                          1/8th Stainless flat bar
                          3/32 308 filler rod
                          1/16 Tungsten Lanthanated
                          # 8 Gas Lens
                          14 CFM
                          120 Amps

                          -Before starting I cleaned both sides of the flat bar with a wire wheel attached to a drill. The wire wheel is only used on stainless.
                          -I cleaned all pieces with acetone before staring, including the bench.
                          -I used a brand new set of tig cloves

                          It appears I did a bit better. The two things that I know I changed from tyring this yesterday was I believe I have the heat a bit higher then I did, and the other thing which I believe was a lot of the fix was I kept the filler in contact with the base metal. Basically never moving the filler rod and just melting it in as I went.

                          That last step I mentioned is a major difference from what I was doing with aluminum. Aluminium I was always puddle, dip, move, puddle, dip, move. It appears if I tried to dip and move with stainless it turns grey.

                          Anyways this is by no means perfect. Please ignore the pin holes and all the inconsistency. I was strictly focusing on not pulling the rod out away from the material.

                          Please any suggestions you may have is much appreciated. Please keep in mind I'm a rookie when it comes to this so I'm sucking all this stuff in like a sponge.

                          It was extremely hard to take pics of these but I tried my best.

                          Bottom right in this picture is where I started, used no filler rod just to see if things were looking correct. I then moved on adding filler from there. Each length there's three seperate attempts. Each time trying I tried to change my control just a little bit. Settings all stayed the same.





                          Last attempt I just used no filler rod again.


                          Back side

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                          • #14
                            Very top picture, top lap joint, left hand weld looks pretty good. You notice towards the edge it still starts to grey up a little-- that's excessive heat. I've found when welding up to an edge w/stainless it's better to stop an inch short, then start at the edge and work back towards the previous weld for a "bow tie" style tie in. Remember you're looking for a "straw" or slightly "salmon" colour in the finished weld. You're definitley getting the hang of it though, keep it up!!
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                            • #15
                              Keep practicing brother, you'll get it. This is mine, still needs work though.
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