metal vs metal reaction

[Endz0r]

i have a question. i want to cut off the BOV flange off my hks upper intercooler pipe and put it on my new piping im making myself out of mandrel bent aluminized pipes for my FMIC.

the question is, if i weld the BOV from the HKS UICP onto the new pipes, will there be any problems with corrosion? i know certain metals like to attack each other, and i'm not sure what kind of metal the HKS is used out of.

 

[dmak]

i would like to know the answer too...coz i also have a hks bov, and i am going to get custom ic pipe soon....

 

[funguy]

hmmm, i have a list in one of my aircraft maintenance books. ok got it.
in the order of most anodic.
magnesium
zinc
aluminum alloy
mild steel
lead
tin
copper
stainless steel
silver
nickel
chromuim
gold

i'm not sure what its made out off, so you gotta find it out.

 

[Defiant]

i have a question. i want to cut off the BOV flange off my hks upper intercooler pipe and put it on my new piping im making myself out of mandrel bent aluminized pipes for my FMIC.

the question is, if i weld the BOV from the HKS UICP onto the new pipes, will there be any problems with corrosion?

Um... isn't the HKS aluminum? You figure out how to weld that to aluminized steel on earth, and you're not going to have to worry about driving DSMs anymore.

Unless submerged in salt water, dry dissimilar metals will have negligible electrolysis issues.

 

[Tallen]

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=43951&item=7934296306&rd=1
Heres a quick solution....but chances are that both of your pipes are steel, so all should be well.

 

[Omega]

What Defiant is saying is that you can weld Al to Al or steel to steel, but not Al to steel.

 

[LaserDad91]

Welding dissimilar metals is not uncommon. I do think steel studs to aluminum plate has been done, but not by using the MIG process. You have to use a solid state process.

Welding is a microscopic bond, not macro. So any process that promotes the transfer of molecules to interlock can be used to join dissimilar metals. You do not necessary have to melt the metal to weld it. (ie. Ultrasonic, High Frequency, Friction Welding, Resistance Welding, and most recently, Friction Stir Welding). However, most of these processes are not readily available to the average person.

As far as electrolysis..........it is also a transfer of molecules from one metal to the other which forms the bond. Electrolysis does not require any external energy input to occur. Therefore a reaction will take place. Even humidity in the air can cause a reaction. Water does not have to be salty, just that the salt speeds up the reaction. The dryer the air, the slower the reaction. The higher the heat the parts are exposed too, the faster the reaction.

The link above would suggest the flange is steel. Looking at some pics of the BOV, it appears the “body” is cast steel, with aluminum pieces (the valve assy.?) attached to that body. So….I would assume the flange is cast steel. Not good.

Welding cast steel is tricky, requires preheat and post heat (~700 – 1300 deg F), and a Nickel based alloy filler material, which resists grain boundary cracking, which is a direct result of the iron carbides found in cast steel. Due to the cracking issue, generally speaking, welding cast steel is avoided.

The weld will be OK, but the cracking occurs in the cast steel. The preheat, and post heat slows the cooling rates, relieve stress, and helps blend the “molecular mix” back to the original casting properties. I once used a self cleaning home oven, set on “clean” (~900 deg F) to do this, but we are talking, say, 3-4 hours of pre heat, then weld, then 6-8 hours or so…post heat…and you do not let the part cool in between the pre heat, weld, post heat cycle…and you do not let the part cool at normal room temp after the process, you turn the oven off and let the whole thing cool….. The resulting repaired part, lasted longer than any previous repair done before (at this particular company), but it still eventually failed. Processing is important, (time consuming), and a domestic oven is not the best thing to use, but all we had!! So, you see why welding of cast steel is avoided.

The body could also be made of powdered metal steel. Generally, PM parts do not have the coarse surface of cast parts, they are smooth like “normal” plate steel. Based on the latter, it is probably cast.

You will be better off to buy the piece listed above, or copy and make a new flange from steel plate, then weld it to your steel aluminized piping. Welding aluminized piping is not uncommon, but creates an area at the weld that will not be resistant to corrosion. It is also suggested to grind the coating off at the weld joint. Using the steel plate and the aluminized piping eliminates the requirement for the special alloy filler material. Have the flange fit over the pipe and use a fillet weld. This will yield a stronger weld joint, since the weak link, the cast steel, is eliminated.

FYI:

Here is a couple of quick ways to tell what material a part is made of:

1. Use a magnet!! As we all know, magnets will not stick to aluminum and some stainless (ie 300 series (shiny finish) which is an austenitic stainless, (common in our exhaust parts) is not magnetic. 400 series stainless is magnetic, but dull and does not polish well at all, and is also common in exhaust applications.
2. Grinding……..steel will throw more sparks than aluminum, if the aluminum throws any at all.
3. Heat – Steel will change color as it is heated, aluminum will not, it just melts, at about 1/3 the temp of steel!!

Hope this helps, good luck, have fun.

 

[Endz0r]

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=43951&item=7934296306&rd=1
Heres a quick solution....but chances are that both of your pipes are steel, so all should be well.

i don't have a HKS BOV, just the HKS uicp with the standard 1g bov flange on it...

i'm guessing i have three choices really...

1) cut out a section of the HKS UICP with the BOV on it, then use two couplers to 'attach' it to the piping i make. that way, there is no reaction to worry about.

2) find a 1g bov flange (or another type of flange and get a new BOV, might as well since i'll be upping my boost soon neways), that is steel, and weld that.

3) cut a section out of the HKS UICP that has the bov flange on it, then uses it as an actual part of the piping.


probably going to go with #3

 

[LaserDad91]

Here is a couple of quick ways to tell what material a part is made of:

1. Use a magnet!! As we all know, magnets will not stick to aluminum and some stainless (ie 300 series (shiny finish) which is an austenitic stainless, (common in our exhaust parts) is not magnetic. 400 series stainless is magnetic, but dull and does not polish well at all, and is also common in exhaust applications.
2. Grinding……..steel will throw more sparks than aluminum, if the aluminum throws any at all.
3. Heat – Steel will change color as it is heated, aluminum will not, it just melts, at about 1/3 the temp of steel!!

OK, I see what your trying to do…….sorry, got the wrong flange.
Keep the above in mind and let’s try this:

WELDING:

Steel to Steel => OK
Steel to 300 series stainless (shiny stainless) => CRACKING, not good, but can be done, use low carbon 300 series filler wire.
Steel to 400 series stainless (dull) => OK only if you use a 400 series filler wire to minimize cracking in the 400 base material.

Cracking is an issue in the following but with correct filler wire, can be done OK.

300 Stainless to 300 Stainless => Use a low carbon 300 series filler wire.
400 Series Stainless to 300 Stainless => Use a low carbon 300 series filler wire.
400 Series Stainless to 400 Stainless => Use 400 series filler wire

Avoid if possible:

Steel to Cast Steel or Cast Iron => CRACKING, not good.
Welding of cast steel => CRACKING, not good, see above
Welding of cast iron => CRACKING, not good, see above.

MECHANICAL FASTENING:

Steel to Steel => RUST!
Steel to 300 series stainless (shiny stainless) => OK, but steel will rust.
Steel to 400 series stainless (dull) => OK, but steel will rust
Steel to Cast Steel or Cast Iron => RUST!
Brass to Steel => Electrolysis
Brass to 300 series stainless => OK

NOTE: The terms “300” and “400” are general and refer to all alloys in those ranges. (ie: 304, 309, 409, 439 etc.)

Maybe that will help!

 

[dmak]

so, would those al pipe be ok?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7935604963&category=38634

 

[LaserDad91]

so, would those al pipe be ok?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7935604963&category=38634

Those look nice and should not be a problem. Al - Steel there is no reaction electrolysis,(ref. aluminum heads on a cast iron block). Only problem is the differance in expansion, as the aluminum will conduct heat and expand faster than the steel. All this means is check your bolts after you have run the car at temp for a bit. Since most of the connections appear to be rubber hose, you should be fine.

 

[Masakari]

lincoln electric makes a multipurpose wire...i want to say 3006b...it will work on stainless to steel welding...just run a hot pass using a TIG welder and then cap it with a few smaller passes for good measure...a good three pass weld using this wire will make the weld hold beyod the breaking points of the metals you are combining