would welding 16 guage ss without using filler metal be strong enough? for downpipe, and intercooler pipings.

 

depends on how well you do it... i usually do it all the time. make sure the pipes are fit PERFECTLY together otherwise it just doesnt work the same... if they do match up all the way round without gaps you can make some awesome welds... intercooler piping usually doesnt take to much stress but you might want to use some filler on the downpipe.

 

I was always taught to use filler, or else the weld would be weak and crack

 

Certainly, no matter how tight a gap is, the fact still remains there is a gap. Your essentially taking the surround metal and using it to fill that gap. In a low stress application it doesn't matter necessarily, but otherwise I would use filler. I have TIG'd without filler many times, but anything that I am welding to sustain any kind of load I use filler on. I mean why not use filler?

 

I agree with RC. Filler is stronger tha your base metal to begin with...unless your piece has absolutely no load at all on it, use filler...what is it like $3 a pound?!
Kyle

 

What's a filler? How you use them with a MIG?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DamWutaDayM3 &raquo;</TD></TR><TR><TD CLASS="quote">What's a filler? How you use them with a MIG?</TD></TR></TABLE>

Are you joking, can't tell sorry. The filler in mig is the wire that comes out of the gun ( I guess you can say )

 

The only kind of welding where you don't NEED filler is TIG. (Well, that, electron beam welding and friction welding)

 

You talking about the spool of wire? Never knew it was called fillers. Then what is the guy talking about welding w/o filler? Is he melting 2 pieces together? And I'm not joking im dumb.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DamWutaDayM3 &raquo;</TD></TR><TR><TD CLASS="quote">You talking about the spool of wire? Never knew it was called fillers. Then what is the guy talking about welding w/o filler? Is he melting 2 pieces together? And I'm not joking im dumb.</TD></TR></TABLE>

Its not really called filler, but I guess you can say its equal to filler, actually probably not, I know engloid would correct me

 

Something's telling me that there's a "technical" term for it that's seldom used...but I can't think of one.

Filler metal is basically any metal that is added to the puddle while welding...but not a piece that is being welded to another.


So, tig wire, or mig wire can be called filler metal.

If you can fuse (no filler) the stainless parts for your exhaust and make it look right, it will hold fine. I would reccomend filler metal for anything up near the engine like a manifold, due to having much more heat.

When you put the two pieces together, get them to fit very tight. A belt sander works good for getting the ends flat and even. When you weld it, you want to be hot enough to melt down the inside, but not hot enough that the weld sinks in and is concave on the outside.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Engloid &raquo;</TD></TR><TR><TD CLASS="quote">

If you can fuse (no filler) the stainless parts for your exhaust and make it look right, it will hold fine. I would reccomend filler metal for anything up near the engine like a manifold, due to having much more heat.

</TD></TR></TABLE> I would not recommend fusion welding the downpipe UNLESS you plan to run a full penetration pass. As far as boost pipes go, don't worry about it...but to run a fusion weld with no carbide precipatation on the back(sugaring, if you aren't back purging), the weld will not penetrate deep enough on that thin of material to sustain the heat of the downpipe. I have First hand experience making this mistake. I fusion welded a bead about 4" down from the turbo...a spirited run a few months later LITERALLY broke the pipes back in 2 pieces...the only bonus was they still fit together like a glove! It just decided to melt the fusion weld(probably .020" deep at best) and separate the pipes like nothing ever happened.

 

the biggest benefit of TIG welding is the ability to join dissimilar metals with the addition of specific alloys introduced via filler rod. when joining two metals of similar makeup such as exhaust, i always try to fusion weld for the sake of economics. its faster, saves money on filler and saves money on the current that would be used to heat the filler.

if the seams are perfectly gapless and the bead is 100% penetrated without being undercut, how can the weld be any weaker than the parent tube? the only thing i could think of would be rapid cooling that leads to embrittlement. just dont do it.
anyways. ive fusion tigged all my exhausts and induction tubes with no troubles. never done manifolds or DPs. i think proper support bracing and flex joints is the name of the longevity game there moreso than fusion weld or filler weld. $.02

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike_belben@yahoo.com &raquo;</TD></TR><TR><TD CLASS="quote">the biggest benefit of TIG welding is the ability to join dissimilar metals with the addition of specific alloys introduced via filler rod. </TD></TR></TABLE>
Although you make a good and valid point, we differ on opinions on what is biggest advantage of TIG welding. I think the biggest advantage is that you have a nonconsumable electrode...which enables you to add filler metal, independently of your amount of heat.

In other words, your heat input on mig will be somewhat limited by the amount of wire you're adding to the puddle. Example....jack your heat up and leave the wirespeed down low and you will likely just burn up your tip in the mig gun.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike_belben@yahoo.com &raquo;</TD></TR><TR><TD CLASS="quote"> if the seams are perfectly gapless and the bead is 100% penetrated without being undercut, how can the weld be any weaker than the parent tube? </TD></TR></TABLE>
It's a metallurgical question here. I don't know a lot of detail and specifics, but will answer in general terms:

When you are welding, there's certain chemicals and compounds that will go into a vapor or can tend to float to the top or bottom of the puddle (especially if you're welding too hot or too slow). When the amount of these things diminish, certain qualities and characteristics of the weld may be lost. For example, welding stainless too hot or too slow can make it such that it looses it's corrosion-resistance and will rust.

Filler metals are not exact copies of the base metal, and are designed to have higher concentrations of the compounds or chemicals that will diminished by the welding process. Typically, when two pieces of metal are welded together, the weld itself will be the strongest part of the part. Also, the heat affected zone will be the weakest....likely because it got so hot that certain chemicals and/or compounds were lost, but not replentished.

A lesson in weld testing:
When a procedure is qualified, you will typically weld up some plate or pipe. A "coupon" or "strap" will be cut such that it has a few inches of each piece and the weld is in the middle. This middle section will be machined down to a specific size and all reinforcement will be removed. This leaves a rectangular or round section in the middle of the piece. So lets say that the middle is machined to be .250" thick and .75-" wide. This piece will then have a cross-sectional area of .1875square inches. The part is then pulled on each end till it breaks. This is called a tensile pull. The machine will measure how much it takes to break the piece. you can then use the cross-sectional area and plug it into a forumla and compare it to what the tensile strength should be, in order to find out if the weld is acceptable or not.

A good weld will break near the weld, not in the weld. A fused stainless weld would likely break right in middle of the weld, not in the heat affected zone....because the welded area will have lost more of the specific strength-adding compounds than the heat affected zone did...and neither had the benefit of replentishment by filler metal.

Another benefit of filler metal is that it will nearly always (to my knowledge), contain silicone, which is the major ingredient of the ball of stuff you see floating on top of a tig puddle. It acts as a magnet of sorts and helps to pull any contaminants to the surface of the weld.

So, in short, welding without filler on your stainless exhaust pipes can be just fine for this purpose and use. However, if you weld it too hot or slow, it may even rust. If you make the weld look good, you're most likely not so hot that you will get rusting problems.

 

thanks engloid. very informative.

 

A few years ago I was installing and welding sanitary tubing for food processing.
Like dairies, creamery's, Soup and stuff like that.Its all 316L .And polished inside and out.Anyway I have put in at least 20 miles of stainless tubing.And never used filler rod.In fact we didn't even have any.Also when I weld SS headers I never use rod and I have NEVER had one crack.And it sure looks a hell of alot better( not hella better )LOL.

 

Yes, many food processing plants will not even allow filler metal on the job. However, most guys that weld that stuff are pretty good and don't have problems welding so hot that problems arise. Strength is rarely an issue in that industry, since the pipe usually only has to hold itself in place...with the help of hangers.

The average hobby welder would be much more likely to have header cracks or rust issues from welding hotter than you would.

Experience goes a long way.

 

Mike Belben....what's up man! It's vtecnitrocrx from TOO's forum. It appears the forums are no more. Has anyone flocked elsewhere that you know of?

 

Engloid or RMF do you have any tips towards what is an acceptable fusion tig weld. even an up close picture so I can see the color, etc... I just need something to shoot for.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by I4sillypwr &raquo;</TD></TR><TR><TD CLASS="quote">Engloid or RMF do you have any tips towards what is an acceptable fusion tig weld. even an up close picture so I can see the color, etc... I just need something to shoot for. </TD></TR></TABLE>
The weld below looks like it sunk in in the middle, but it really is just the bead shape that makes it look that way.

 

Great welds!!!! Welded by hand or machine?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondaapi &raquo;</TD></TR><TR><TD CLASS="quote">Great welds!!!! Welded by hand or machine?</TD></TR></TABLE>
By hand. the inside really was much more even in reality, but for some reason I couldn't get a good pic of it, and the camera seemed to distort it, making it look rather uneven.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondaapi &raquo;</TD></TR><TR><TD CLASS="quote">Great welds!!!! Welded by hand or machine?</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Engloid &raquo;</TD></TR><TR><TD CLASS="quote">
By hand. the inside really was much more even in reality, but for some reason I couldn't get a good pic of it, and the camera seemed to distort it, making it look rather uneven.</TD></TR></TABLE>

Lie. Engloid is a machine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ExploitedRacing &raquo;</TD></TR><TR><TD CLASS="quote">
Lie. Engloid is a machine.
</TD></TR></TABLE>
NOBODY takes pics of their ugly welds... at lease nobody with much sense.


and we all make some.

 

Yeah,That's the way it looks.Maybe the purge pressure was A little low.Because it shouldn't hang in that far.But it would probably pass a swab test.
When you weld that stuff its all in place.So there is no turning it.You start at the bottom and come up ,And do the same on the other side.Two starts that's it.
Engloid,Sure you do .Other peoples ugly welds