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Thread: Forced Induction Section Fabrication Thread

  1. #1826
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    Stainless is my favorite thing to weld. It just flows like butter. Tinfoil is your friend for back purging. I have a separate tank with C02 and a spare tig flow regulator for back purging. I don't back purge anything but tubing. For sheet metal brackets and stuff you just need to put something behind the joint and it doesn't sugar.


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  2. #1827
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    Quote Originally Posted by someguy2800 View Post
    Stainless is my favorite thing to weld. It just flows like butter. Tinfoil is your friend for back purging. I have a separate tank with C02 and a spare tig flow regulator for back purging. I don't back purge anything but tubing. For sheet metal brackets and stuff you just need to put something behind the joint and it doesn't sugar.
    Stainless does flow like butter, but part of the reason is part of why it can be tricky. It takes a lot less amps to weld than comparable mild and it's very unforgiving to lingering which most beginners will do. If you don't have a good rhythm, or use too much amperage, or start welding on a part near another weld before it's cool enough, and the weld won't be good. It's easier with gas lenses, the bigger the better (I have one from CK that's like 1-1/4" diameter which takes 36cfh of Argon, I try to limit it to titanium but it makes stainless very happy too). That said, it's largely an aesthetic problem. From what I've read, the strength of the weld isn't hugely compromised when it discolors or even sugars - I mean it IS compromised but unless you are actually building something structural where you are depending on the outer envelope of the mechanical properties of the material, that's a different matter but most guys in automotive stuff don't use stainless for that. You're just pulling and concentrating chromium so the parts where you pulled it from will not have the corrosion resistance you expect. Guys ooh and ahh at fancy colors of internet stainless and titanium welds but the reality is that in strict code environments, most of those would be rejected. Color means oxidation and therefore compromised weld. Ideally stainless and titanium welds will look silver, anything darker than light straw is often rejected. But if you're mainly using stainless for looks then who gives a shit.

    Backing is a great tip for stainless. It will act like a backpurge setup. Especially if you can clamp the joint to a fat chunk of aluminum then not only will it keep the back of the weld oxygen free but it will also let you get away with using too much heat thanks to the heatsink.

    FYI this stuff is cheap and works very well when backpurging isn't reasonable. Many of you guys have methanol kicking around but that's really mainly a requirement for aerospace, I use it with isopropyl and it works great.

    http://weldfabulous.com/weldcote-met...-b-1pound-can/

    Last edited by TheJuggernaut; 10-18-2017 at 11:33 AM.

  3. #1828
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    I've used that solar flux, and it worked pretty well. But as you said, for performance parts like we on here are usually making, the problems are mostly aesthetic. Still, it's fun to make pretty stuff.

  4. #1829
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    I go hot and fast with aluminum.

    But i prefer stainless


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  5. #1830
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    Quote Originally Posted by vollosso View Post
    I go hot and fast with aluminum
    Give 4943 a shot if you want, it does better with overheated welds than 4043, doesn't precipitate silicon like that (graininess). It's become my favorite all around rod

  6. #1831
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    Quote Originally Posted by TheJuggernaut View Post
    Give 4943 a shot if you want, it does better with overheated welds than 4043, doesn't precipitate silicon like that (graininess). It's become my favorite all around rod
    I've been planning to try some 5356 for similar reasons. Have you compared 4943 to 5356?

  7. #1832
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    Quote Originally Posted by TheJuggernaut View Post
    Give 4943 a shot if you want, it does better with overheated welds than 4043, doesn't precipitate silicon like that (graininess). It's become my favorite all around rod
    Awesome, ordered some for this weekend.


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    1998 Turbo: PTE6870 | 1.15 ar | Hp Cover, Custom Divided T4 bottom-mount, 3.5" SS exhaust, Dual Turbosmart Compgates, Turbosmart Raceport BOV, 3.5" Treadstone Intercooler, 3.5" Vibrant resonator and muffler, Arp 2k Headstuds | Arp 2k Main studs | 87mm Je pistons | Eagle rods | 9.2:1 static compression, Ces 87mm cutring, Custom solid rear subframe bushings, Akg 85d diff bushings, 4 clutch 3.15 diff, , Poly engine mounts, UUC trans mounts W/ enforcers, 22RPD OBD2 Stock ECU id1700 E85 tune, 22RPD Big power Transmission swap w/ GS6-53

  8. #1833
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    Quote Originally Posted by tptrsn View Post
    I've been planning to try some 5356 for similar reasons. Have you compared 4943 to 5356?
    4943 is the best of both worlds, it flows as nice as 4043, looks as good as 5356, almost as strong as 5356 (unfortunately anodizes like 4043)... it's basically the ideal rod unless you're actually welding 5000 or need to anodize. I went on a search for an alternative because I wanted to switch to 5356 and I found out about stress corrosion cracking. Now, this scared me enough to go on the search and I found 4943 which Hobart had just concocted, but it's really not as big a concern as the internet old welding wives want you to believe. I managed to get a hold of the fucking director of aluminum technology at Lincoln Electric who kind of gave me the lowdown on it. He said that these warnings are written for critical applications. Basically, if you expose a 5356 weld to high temperatures in a corrosive environment and significant stress relative to its yield, then after hundreds or thousands of hours, it may crack. For instance, a boat hull next to an exhaust. But, still feels better to use the right thing.
    Last edited by TheJuggernaut; 10-18-2017 at 01:25 PM.

  9. #1834
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  10. #1835
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    4943 was really expensive when I looked into it. I generally like 5356 because it does tolerate higher temps better than 4043 and it has higher strength.

    Stress corrosion cracking is something you generally won't find on a car - just not the sort of environment to come across it.

  11. #1836
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    Last edited by Butters Stoch; 10-18-2017 at 02:22 PM.
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  12. #1837
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    Quote Originally Posted by Def View Post
    Stress corrosion cracking is something you generally won't find on a car - just not the sort of environment to come across it.
    Much of the aluminum welding on cars is in the cooling system which would meet the criteria for SCC but most cars would probably end up on the scrap heap before the cracks happen. Or maybe that's why a lot of aftermarket alu rads develop leaks *shrug*

  13. #1838
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    You guys are way over my head on aluminum. I go to the welding shop up the road and say "give me aluminum filler rod". I'll have to try that 4943.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
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  14. #1839
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    Quote Originally Posted by TheJuggernaut View Post
    Much of the aluminum welding on cars is in the cooling system which would meet the criteria for SCC but most cars would probably end up on the scrap heap before the cracks happen. Or maybe that's why a lot of aftermarket alu rads develop leaks *shrug*
    SCC only happens in VERY specific circumstances. Typical requirements are an environment that is aggressive to the base metal with no oxide layer and a cyclical stress input that usually reverses (for it to be "bad"). I am struggling to come up with any part of the cooling system that would easily meet the above criteria.

    The cooling system being over the temperature (150 deg F) where Mg can precipitate out will make it more susceptible, but you still need a loading profile and a corrosive enough environment to make it all happen. I'm not saying it's 100% impossible, but it's not a very common situation to find in a car because no environment is really that corrosive when it comes down to it (barring road salt, which is the corrosion demon).


    The reason SCC is brought up is that if the conditions are there, the failure happens VERY quickly, and it's a very unique failure mode due to each stress cycle exposing the base metal to corrosion, which eats away a bit, then the next stress cycle is a bit higher stress with the same loading due to the crack growing larger, which then corrodes even more, crack grows, stress is larger next cycle, etc. repeat until failure.

  15. #1840
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    That's not quite the failure mode as it was explained to me by the Lincoln engineer, although he did agree that it's very unlikely to be of any concern in a race car. Instead of butchering his words I'll just relay them, as I did ask his permission to do so

    In order to get stress corrosion cracking (SCC), you need 3 things. First you need a susceptible microstructure. You get that when you expose any aluminum alloy containing more than 3% Magnesium t(5356 has 5%Mg) to temperatures higher than 150 degrees F for long times – 100s or 1000s of hours as I said. Second, you need a stress. Usually the residual stresses around a weld are more than enough. Last, you need an electrolyte – salt water is the worst, but any impure water will also work and cause SCC. If you take any of those 3 factors away, you won’t get SCC.

    So if you only expose the 5356 to atmosphere (not to engine coolant), you won’t get SCC.

    SCC is actually fairly common. You usually find in marine environments. The US Navy, for instance, is having a problem right now with a class of aluminum hulled ships that are cracking where the engine exhaust pipes come out of the 5083 aluminum hull. In 2016, I encountered a problem on a large aluminum hulled yacht where the hull was cracking from SCC. Why? Because the builder routed the engine exhaust piping right up against the 5083 hull. The solution was easy. Fix the cracks and move the exhaust piping inboard a bit so it didn’t get the hull hot.

  16. #1841
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    His first paragraph is exactly what I am saying, he just used some different terms.

    Quoting the relevant sentence from my post that brings all 3 things together he mentions:

    The cooling system being over the temperature (150 deg F) where Mg can precipitate out will make it more susceptible, but you still need a loading profile and a corrosive enough environment to make it all happen.

  17. #1842
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    Good thing we are all fabricating racecars to meet aerospace standards. All my parts will probably fall out of the car cause my ashtrays haven't been sliced, diced, etched, polished and or xrayed.
    Dam we are screwed.

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  18. #1843
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    Quote Originally Posted by Def View Post
    His first paragraph is exactly what I am saying, he just used some different terms.

    Quoting the relevant sentence from my post that brings all 3 things together he mentions:
    Not quite, you said that you need cyclic stresses and it happens quickly. He is saying it can take hundreds or thousands of hours and residual stress in the material from the welding can be sufficient.

  19. #1844
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    Quote Originally Posted by TheJuggernaut View Post
    Not quite, you said that you need cyclic stresses and it happens quickly. He is saying it can take hundreds or thousands of hours and residual stress in the material from the welding can be sufficient.
    You can have a high constant stress level cause SCC, but it typically takes a much MUCH longer time than a reversing stress. This isn't a black and white failure mode, it's an interplay between corrosion causing a crack, and that crack propagating to a failure. Adding cyclical fatigue into the equation is when I've seen the failures happen *VERY* quickly, as the two . The SCC from a constant residual stress would take far longer to manifest itself.

  20. #1845
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    Quote Originally Posted by Def View Post
    You can have a high constant stress level cause SCC, but it typically takes a much MUCH longer time than a reversing stress. This isn't a black and white failure mode, it's an interplay between corrosion causing a crack, and that crack propagating to a failure. Adding cyclical fatigue into the equation is when I've seen the failures happen *VERY* quickly, as the two . The SCC from a constant residual stress would take far longer to manifest itself.
    I understand, it makes perfect sense that a greater, cyclic stress will cause failure much faster. My point is that the failure mode he is describing is a lot more unpleasant as a part that seems to be fine after being in service for a long time, can then suddenly fail with no apparent abuse. It's the thing that made me re-do my thermostat housing because I don't want to be left wondering if and when that will be.

  21. #1846
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    Back to what is relevant,
    To change the subject.
    I promised the creator of this tungsten grinder I would drop a plug. These can be found on eBay I'll post a link later.
    But here are 3 must haves for any of you guys starting out.
    These "tig fingers" created by Jody Collier, he is the man behind "welding tips and tricks". He sells on eBay and his store weldmonger.com.

    As for the tungsten grinder. These things are stupid money for a proper one. Iirc our very own 5mall5nails also developed a kit that will use a HF diamond wheel with a bench grinder. This one simply screws on to a dremel. Works like a charm. Cheap money too. Like $45 or something.
    You can grind down to a needle point, arc doesn't wander at all. Good product.
    Well worth the money. Obviously a stubby lens kit as well. But I'm sure no need to push that, as everyone knows.




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    Last edited by Butters Stoch; 10-22-2017 at 08:59 AM.
    1996 332IS
    Built 3.2
    CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
    Technique Tuning 80# tune.
    1/4 mile 10.84 @ 136.72
    Your 1 and only stop for all your BMW performance needs
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  22. #1847
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    I use an electric drill and a circular saw blade sharpener from harborfreight. It’s under 50 bucks with coupons and replacement diamond blades are 10. Gets me a perfect grind at any angle I want in seconds and the edge of the blade trims the tungsten quickly if I welded a bunch of filler rod onto the tip

    https://m.harborfreight.com/120-volt...not%20provided

  23. #1848
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    What I really want to know is whether that sharpener works well on carbide tipped blades for 14" dry-cut saws? My last blade lasted through about one cut of 4" 416 stainless tube before it was dull... I certainly won't be using that blade on stainless again, but I'd like to sharpen it back up for aluminum.

  24. #1849
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    Use a band saw


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    2004 Built motor TiAg/Black - Sold
    2008 E61 19T Turbo-Wagon - current
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    1998 M3 Cosmos S54 swapped Sedan - current

    1998 Turbo: PTE6870 | 1.15 ar | Hp Cover, Custom Divided T4 bottom-mount, 3.5" SS exhaust, Dual Turbosmart Compgates, Turbosmart Raceport BOV, 3.5" Treadstone Intercooler, 3.5" Vibrant resonator and muffler, Arp 2k Headstuds | Arp 2k Main studs | 87mm Je pistons | Eagle rods | 9.2:1 static compression, Ces 87mm cutring, Custom solid rear subframe bushings, Akg 85d diff bushings, 4 clutch 3.15 diff, , Poly engine mounts, UUC trans mounts W/ enforcers, 22RPD OBD2 Stock ECU id1700 E85 tune, 22RPD Big power Transmission swap w/ GS6-53

  25. #1850
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    I'm trying to formulate a joke out of using a bandsaw to sharpen a circular saw blade, but I'm coming up empty.

    Seriously though, for pie cuts, the dry cut saw is titties. **IF** the blade is up to the task presented by the material...

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