Hallo,

i'am posting this for a friend because he as no internet access and he need a hit very urgent.

here are the pics:

manifold material was 309 and flange material was 316... welded without backpurging

what can cause this failure and what can we do to prevent this in the future?





Thanks
Malte.

 

Was there any support for the turbo? You need something that goes from the flange to the engine block to take off some of the weight from the turbo. You also need flexjoints everywhere. the downpipe needs one, along with the wastegate if you run one.


What was the setup like in the car?

 

Hi,

there was no support of the turo to the block... the turbo was a standard t3 i guess... flexpipes was used in the DP... turbo is internaly wastegated...

 

wow even the flange cracked right through.

 

Well welding without a backpurge is part of the problem, and is more then likely a large contributing to factor to the failure

Did you use the right welding rod? are you sure the materials is 309? and 316?

having no support is going to be another contributing factor.

I think what it comes down to is there was a lot of improper fabrication, that took place and all these little things contributed to the failure

 

first ram horn manifold that i've ever seen failed. how thick was it? sch40?

 

From the looks of it, I would say the flange was warped (hogging) when welded, and you torqued the **** out of the bolts to force the flange to seal.

I say this because it is unlikely that the cracked started in the collector and propegated through the flange instead of just going around the perimeter of the collector. More likely is that large internal stresses in the flange itself combined with heat cycling caused a fatigue failure in the flange, which then propegated through the relatively weak collector.

 

who made the manifold?

 

i would go with the support issue first, support is critical with stainless. i have seen many manifolds crack over the years because lack off support. i have also seen many poorly fabricated yet supported manifolds live happy lives (rebx)

 

good theory now that i look at it i tend to agree damn me in my haste to provide an answer i didnt look at the details

 

I´m the one who welded this mainfold. It was the first manifold that I have build two years ago.

The collector was lasercuttet 309 (here in Germany 1.4828) - 3.2mm thick
The flange was lasercuttet 316 (her in Germany 1.4571) - 10mm thick
Unfortunatly not backpurged - Turbo not supported to the block.
The filler was the right one - I´m very sure about that.

All flanges were warped-thats right. But after welding I machine every flange to be absolutely flat.

We used a T3gasket - relative thick -but just in the middle - so maybe that the bolt torqued the flange?

Other problem we had with that manifold was that we hat breacking bolts/nuts at manifold-to-turbo-flange very often and so I saw yesterday that the holes were not in the exact same location as the holes from the turbo.
So the bolts were shired (hope it is the right word)

I´ll take a new flange with reliefs and will also add reliefs on the head flange also throw the gasket out and suport the turbo. - Some pics of such supports????

Every more suggestions are very welcome.

Thanks
Kevin

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondaapi &raquo;</TD></TR><TR><TD CLASS="quote">I´m the one who welded this mainfold. It was the first manifold that I have build two years ago.

The collector was lasercuttet 309 (here in Germany 1.4828) - 3.2mm thick
The flange was lasercuttet 316 (her in Germany 1.4571) - 10mm thick
Unfortunatly not backpurged - Turbo not supported to the block.


Other problem we had with that manifold was that we hat breacking bolts/nuts at manifold-to-turbo-flange very often and so I saw yesterday that the holes were not in the exact same location as the holes from the turbo.
So the bolts were shired (hope it is the right word)
</TD></TR></TABLE>

bingo...connect the bold.

"Stainless always acts like stainless."

mild steel is a far better metal to use for the flange since it does not heat-warp like stainless does.

 

Mild steel flanges the solution????


Do you have any AISI numbers for the mild steel.
Nobody here knows "mild steel" with material numbers it is much easier for me to search for. Do there "mild steels" rust after a time?

Thanks

 

A36 Hot Roll
1018 Cold Roll

 

Is there also a possibility to prevent such cracks and still to use stainless steel?

 

im sure if there was we would be using it on our manifolds. but we dont, NONE of our flanges are stainless.

 

If the turbo flange was flat I guess that puts the support issue as the leading cause. It's pretty strange that it broke through the entire flange....

 

See now this is interesting, we dont have failure likes this using 3/8" flnages but the 1/2" flanges seem to run into this from time to time. I wouldnt really blame them there could be quite a few others thing's going on

 

I got a question, how come so many big name companies use stainless steel then ? Does it have something to do with looks maybe ? I don't know, I just think coated mild steel is the better way to go.

 

Mild steel has a higher melting point than stainless.

However there melting characteristics are very interesting.... stainless requires more current than mild to get it to flow.

I havent taken Material science yet...but soon. Im sure the guys at FR have taken plenty of MS courses.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RTErnie &raquo;</TD></TR><TR><TD CLASS="quote">Mild steel has a higher melting point than stainless.

However there melting characteristics are very interesting.... stainless requires more current than mild to get it to flow.

I havent taken Material science yet...but soon. Im sure the guys at FR have taken plenty of MS courses. </TD></TR></TABLE>

Huh? stainless requires less amps to weld....

edit: I'm not really sure what your post meant. The reason mild steel is used for flanges is that it expands less. it's the expansion of the stainless combined with holes without enough clearance that shear the head studs. At least thats how I understand it.


Modified by I4sillypwr at 2:31 PM 9/29/2005

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by I4sillypwr &raquo;</TD></TR><TR><TD CLASS="quote">

Huh? stainless requires less amps to weld....

</TD></TR></TABLE>

true - ss takes 1/3 to 1/2 the amps of mild to tig, and not because of lower melting point, but the fact that it doesn't shed the heat like mild does - the heat builds up and requires fewer amps to add additional heat to melt

 

What about the corrosion with mild steel.

I work at Porsche and they seem to use stainless for the runners and an other material for the flanges. The flange material looks totaly rusty after a short time with little flakes breaking out. That looks terrible.

Damn- in this topic is so much to learn :-)

 

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

true - ss takes 1/3 to 1/2 the amps of mild to tig, and not because of lower melting point, but the fact that it doesn't shed the heat like mild does - the heat builds up and requires fewer amps to add additional heat to melt</TD></TR></TABLE>

I found this extremely true more recently... i used to fabricate a lot of parts with mild steel way back in the day and took about 75 amps to weld 16 gauge mild tube... i recently just started to use 16 gauge stainless.. and have had no problems welding it up at 35amps! Dont quite understand how that works..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by I4sillypwr &raquo;</TD></TR><TR><TD CLASS="quote">Huh? stainless requires less amps to weld....

edit: I'm not really sure what your post meant. The reason mild steel is used for flanges is that it expands less. it's the expansion of the stainless combined with holes without enough clearance that shear the head studs. At least thats how I understand it.


Modified by I4sillypwr at 2:31 PM 9/29/2005</TD></TR></TABLE>

bingo..