How to make these welds better?

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Hey all,My friend TIG'd my flange onto this pipe I am using for a piece of exhaust.  I am pretty satisfied with the results honestly, but does it look good technically?  Theres not much "color" to the "dimes" but I am not sure if thats good or bad.  I wiped the metal down in paint thinner and let it evaporate before welding.We TIG'd a butt-joint but didn't have much luck.  I had him try it without filler first but it didn't want to go.  I think our heat was way too high on the butt-joint and I couldn't get "dimes" to form, just like flat "streaks" if you will, and looking inside the pipe, it sank in.
Reply:Color is worse than good as it is oxidizing in action.  Oxygen+metal=bad news bears.  But you are undercutting a bunch.  Not good.  Other than that, looks good.
Reply:Undercut is due to heat I assume?
Reply:Yes to much heat and not enough filler
Reply:Originally Posted by WelderBoyColor is worse than good as it is oxidizing in action.  Oxygen+metal=bad news bears.  But you are undercutting a bunch.  Not good.  Other than that, looks good.
Reply:Undercut can be caused partially by having dull tungsten also...which fans out the arc and erodes the base material so far away that you're not filling it with filler metal.
Reply:You made no mention of what the material is? Looks like it's regular old mild steel tailpipe material, is it?Paint thinner?Like mineral spirits kind of paint thinner?It's got an oily base to it ... and will leave a residue on teh material.I would suggest as most others would here to use acetone. Washman
Reply:Originally Posted by WashmanYou made no mention of what the material is? Looks like it's regular old mild steel tailpipe material, is it?Paint thinner?Like mineral spirits kind of paint thinner?It's got an oily base to it ... and will leave a residue on teh material.I would suggest as most others would here to use acetone. Washman
Reply:Originally Posted by Jon KI know I wanted to use acetone and a wire wheel to clean but I didn't that at the time.  Both pieces are 304L.  My friend says he used Argon/Co2
Reply:Originally Posted by Rojodiablo[/B]That's the coloration problem right there. Use pure argon for tig.
Reply:Originally Posted by WelderBoyAnd maybe the undercutting problem too...
Reply:It's good to go. I would not bother to go back over it, as it is not a BAD weld, just a weld that wasn't cosmetically perfect.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:i know it's exhasut, but what is is goingon exactly? it doesn't look like a car due to the flared part of it. unless you are running an excessive amount of boost or some other high-flow, high-powered application, then you could probably braze or solder them together and they'd hold. not that i'm reccomending it, but all i'm trying to say is that with most exhaust and intake applications, the main force acting on the part is the weight of itself. the exhuast gasses and pressures aren't enough to really worry about much. with high-reving engines, or engines with large amounts of air running through them, there may be a better chance of a strong internal pressure being present, but 70-90 % of the time, you won't have any problems as long as the metal is sealed tight and doesn't move when you try to bend/twist it in your hands.hope that helps,Andy
Reply:one more thing, if you want to make the weld "disappear" and you are willing to take the time to do it, i've seen it done to stainless. if you paint it, it's a lot easier and less time consuming (you jsut grind it smooth and paint it and the joint doesn't even seem to be there), but if you take your time and do it to stainless it looks awesome. first start by grinding the weld bead down flush with the res tof the metal, then take some sand paper by hand to get a smooth finish. next, take some brillo pads and/or steel wool (Brillo works better) and start wiping the joint in the same direction as the finished grain moves with the rest of the pipe. i know it's hard to understand it by the way i've tried to explain it. sorry if i've confused you all. if you CAN undestand it, and you try it, i promise it looks awesome. my buddy did it with his dad on a '70 cuda. i don't have pictures. his dad said he saw it on one of the car shows on Spike TV on saturday and sunday mornings. "HorsePower" maybe?Thanks,Andy
Reply:You NEVER should tig weld with any gas that contains CO2...unless it's all you have an it's something that's not very critical.  That stands for ALL metals.
Reply:Originally Posted by aczelleryou could probably braze or solder them together and they'd hold. not that i'm reccomending it, but all i'm trying to say is that with most exhaust and intake applications, the main force acting on the part is the weight of itself.
Reply:sorry. maybe i wasn't clear enough. i did not mean to sound like a moron (even though i may have sounded like it), but if an exhaust system is set up correctly (with flex pipes and proper hanger locations), the MAIN force that will be acting upon the exhuast system will be gravity. yes, gravity will use momentum of the vehicle and exhaust system while going over bumps and the engine is running/vibrating, however, there is not much internal pressure on an exhuast like that, thus requireing the flared out section on the pipe. yes, the flare will create a bit more back-pressure, but the force being generated by this internal pressure is not enough to worry about. when was the last time you ever heard of an exhuast pipe exploding due to excessive back-pressure? i know that will probably come back to bite me in the butt (someone out there has a story like that). anyway, i nevercondone soldering the pipes. i realize the temperatures being generated on exhuast pipes can be well in excess of 1000 degrees, which can melt solder. all i was trying to imply was that if the weld looks like it is water-tight and it looks reletively clean (no "globs" of weld), it is more than likely sound enough to put onto an exhuast system and run it. in this particular case, if you are not happy with it, or feeling unsafe about it, re-weld it. in my personal experience working on cars (and i know that i don't have much compared to many other members here), i have found that 95% of the time i don't think something will hold up, it doesn't. the few times i think it will be fine, about 70% of the time it still isn't. i know it's not a great track record, and it's not a thread about how bad i am at working on cars, but i'm trying to make a point. my general rule of thumb that has never let me down is that when you think something is good enough, do it better. after you do it better, re-evaluate what you have and do it again. if it still doesn't work after that, take it to a professional. if it doesn't work for them, you are SOL.sorry for the confusion.Andy
Reply:The weld may rust, and look bad after a while, but it's not going to break under  normal circumstances.Do keep in mind that sometimes a professional will charge more money to repair something than to do it the first time....especially if it's got JB Weld on it.  I'd rather gind steel than grind that stuff.
Reply:Originally Posted by aczelleri know it's exhasut, but what is is goingon exactly? it doesn't look like a car due to the flared part of it. unless you are running an excessive amount of boost or some other high-flow, high-powered application, then you could probably braze or solder them together and they'd hold. not that i'm reccomending it, but all i'm trying to say is that with most exhaust and intake applications, the main force acting on the part is the weight of itself. the exhuast gasses and pressures aren't enough to really worry about much. with high-reving engines, or engines with large amounts of air running through them, there may be a better chance of a strong internal pressure being present, but 70-90 % of the time, you won't have any problems as long as the metal is sealed tight and doesn't move when you try to bend/twist it in your hands.hope that helps,Andy
Reply:If you really wanted to you could grind it down to bare metal and then go over it with more filler at a slower rate with argon shield, I don't think you will have any problems but on a high revving 6 cylinder turbocharged engine you certainly aren't babying it. To me it looks light on the filler and a little overheated (don't know about CO2 vs. Argon) but probably pretty damn strong. I would however recommend welding in a flex joint while you're at it.
Reply:Originally Posted by Jon KIt is going on a car its an inline 6 bmw with a large turbocharger stepping from 3.0" to 4.0" for the exhaust.
Reply:Way too much heat on that one. I use a 1/16 red and .030 - .035 filler for v-band to tubing. 70 amps max...Miller Dynasty 200 DX(love it!, well I did, now its a paperweight)Miller fixed it, haven't used it much yet $2900 warranty Miller 210 Thermal Arc UltraFlex 350Cobra Push-Pull Wire feedLots of other things