BenB
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| posted on 10/1/09 at 06:55 PM |
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Welding stainless with mild steel wire / CO2
If I'm going to paint the stainless anyway, can I weld stainless with mild steel wire under CO2 shield???
I know to retain the stainless properties of the workpiece you need to use stainless wire and funky gas but is that the only advantage ie it is
isn't that you get cr@ppy birdpoo type welds or anything else....
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jacko
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| posted on 10/1/09 at 06:57 PM |
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You will be ok but the weld will rust in time
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BenB
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| posted on 10/1/09 at 06:59 PM |
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Cool! No problems. Going to get painted anyway!!!
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blakep82
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| posted on 10/1/09 at 07:04 PM |
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good to know! i want a stainless exhaust, but i've got a mild steel flange (well, I haven't but the engine has  )
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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zilspeed
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| posted on 10/1/09 at 07:12 PM |
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That's exactly what my exhaust is.
Originally a stainless steel bike manifold, it was welded with mild wire and CO2.
Just take your time and watch the power settings if its thin stuff.
Today's project was 3mm mild onto 3mm mild, so I just whacked the power right all the way up 
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BenB
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| posted on 10/1/09 at 07:19 PM |
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Blowing holes in anything ain't a problem with my welder- it's only a 90A model!! Unless its 0.0001mm I'll be okay!!!
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jlparsons
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| posted on 10/1/09 at 07:30 PM |
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Wouldn't you have the same problem as with aluminium boats and stainless steel fittings, with the mild steel acting as a cathode and rotting
away much faster for being joined to the stainless?
I've no experience at all welding stainless to mild, but this is what I'd be worried about if I were doing it.
Any resemblance to real persons, living or dead is purely coincidental. Some assembly required. Batteries not included. Contents may settle during
shipment. Use only as directed. No other warranty expressed or implied. Do not use while operating a motor vehicle or heavy equipment. Subject to
approval, terms and conditions apply. Apply only to affected area. For recreational use only. All models over 18 years of age. No user-serviceable
parts inside. Subject to change. As seen on TV. One size fits all. May contain nuts. Slippery when wet. For office use only. Edited for television.
Keep cool; process promptly.
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stevebubs
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| posted on 10/1/09 at 07:35 PM |
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My fisher stainless exhaust looks like the head flange was welded to the downpipes with mild steel...
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flak monkey
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| posted on 10/1/09 at 07:40 PM |
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No galvanic corrosion between stainless and mild as stainless is still most iron anyway.
You can weld mild to stainless no problem in non critical applications. Similarly you can use mild wire to weld stainless no problems (other than the
weld will rust in time...)
Weld away
David
Sera
http://www.motosera.com
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jacko
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| posted on 10/1/09 at 07:53 PM |
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twin SU carbs/1
The manifold you can see is s/steel pipes welded to m/steel plate using m/steel wire in a mig
Jacko
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smart51
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| posted on 10/1/09 at 08:01 PM |
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Stainless steel is mostly iron with a couple of percent carbon and, at lest on some grades, 26% chromium, plus perhaps other alloying metals. Mild
steel can be mostly iron with a bit of carbon and some other stuff. MIG Welding wire is coated in copper.
When you weld, you melt both sides of the metal and the welding wire. What cools is an alloy of all 3 which sort of fades in concentration between
the two metals joined. Welding mild to stainless, you'll see rust on the mild part anyway, so why worry.
Welding stainless to stainless with mild wire, I'd expect the concentration of Chromium to be lower in the weld than the parent metal but it
still might resist rusting in a gentle environment, especially if the stainless was a good grade and the joint had almost no gap.
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MakeEverything
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| posted on 10/1/09 at 09:08 PM |
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Ditto. When youve welded stainless with MS wire, you can oftern see the different metals in the weld, or certainly the pool.
Perfectly ok if painted, but i wouldnt use it structurally.
quote:
Originally posted by smart51
Stainless steel is mostly iron with a couple of percent carbon and, at lest on some grades, 26% chromium, plus perhaps other alloying metals. Mild
steel can be mostly iron with a bit of carbon and some other stuff. MIG Welding wire is coated in copper.
When you weld, you melt both sides of the metal and the welding wire. What cools is an alloy of all 3 which sort of fades in concentration between
the two metals joined. Welding mild to stainless, you'll see rust on the mild part anyway, so why worry.
Welding stainless to stainless with mild wire, I'd expect the concentration of Chromium to be lower in the weld than the parent metal but it
still might resist rusting in a gentle environment, especially if the stainless was a good grade and the joint had almost no gap.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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jlparsons
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| posted on 10/1/09 at 09:12 PM |
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Stainless steel is anything with 10% chromium or greater, less than that and the passive oxide film doesn't regenerate so the protection
dissapears. So if the merged mild and stainless in the weld ends up less than 10% it will rust like mild.
I did a bit of digging - apparently the shipping industy uses mild steel as an anode to protect stainless against crevice corrosion, so there must be
some galvanic action there. No idea how much though, but I wouldn't be doing this with an exhaust with all its nasty corrosive gases, or with
anything structural.
Any resemblance to real persons, living or dead is purely coincidental. Some assembly required. Batteries not included. Contents may settle during
shipment. Use only as directed. No other warranty expressed or implied. Do not use while operating a motor vehicle or heavy equipment. Subject to
approval, terms and conditions apply. Apply only to affected area. For recreational use only. All models over 18 years of age. No user-serviceable
parts inside. Subject to change. As seen on TV. One size fits all. May contain nuts. Slippery when wet. For office use only. Edited for television.
Keep cool; process promptly.
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907
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| posted on 11/1/09 at 01:22 AM |
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Hi.
When welding stainless steel to mild steel the filler rod/wire to use is 309 stainless. (or 312)
Paul G
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