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Up Topic Welding Industry / General Welding Discussion / Gas/stainless steel 304/carbon steel
- - By CHEVYTOWN13 (**) Date 03-15-2004 01:38
Hey folks. I have been doing some research trying to find out a couple of answers prior to going to the welding shop. I was researching at this hometown's website but couldn't find what I was looking for.

I'm getting ready to weld me bro's stainless steel (304) exhaust. He gave me some scrap to practice on....When I originally picked up a 150 bottle with the 75/25 mix to try GMAW for the first time on carbon steel, I was told by the welding shop that I would be able to weld the SS (with the carbon steel gas mix/Lincoln super arc MIG wire) but could not gauruntee the results. Using the 75/25 mix and Lincoln's super arc MIG wire, I was able to weld the SS tubing. Obviously, not the optimum result, but it worked like they said it would...

Here's me questions hometown's...Using the MIG process, can the gas mixture for stainless steel also be used for carbon steel as a shielding gas?

OK, here's where the eye's are prolly gonna roll...

The reason why I'm asking this is because instead of filling my 150 bottle with expensive gas??? to weld me bro's SS exhaust (which is not much), I was thinking of investing in a small 50 bottle for small jobs like this one.

I'm also finished with a gate I made for my bro's new crib. Alls I have to do is hang the gate. Will the SS gas mixture and SS wire weld carbon steel OK? I'm trying for the "killing two with one stone" routine.

Or is this looney toon times...

Parent - - By welder_guy2001 (***) Date 03-15-2004 06:16
You can use 75/25 gas on 304 SS w/ E-309L. That's a wire specially designed for use where you have a lot of carbon present in the base metals...which you do because of the 25% CO2 you have in the gas.

You don't want to buy very much SS's about 4 times as expensive as carbon steel wire! You could buy the 2 lb (or are they 1 lb?) rolls of SS and CS wire and save yourself a lot of money that way. I think a 2 lb roll of CS wire is around $5...and SS would be around $20.
Parent - By CHEVYTOWN13 (**) Date 03-15-2004 08:35
Thanks a ton for your response hometown.

Will the E-390L(esab?) wire be OK left alone after the welds are completed or will the welds have to be coated with somekind of protection?

We're looking for the final product to be the weld itself with no coating involved. Will that be possible using this wire and the 75/25 mix?

I greatly appreciate your response. I'll have a better understanding for later this week when I hit up the shop...

Parent - - By Tim Buyle (**) Date 03-15-2004 12:20
Of course you can use a 75/25 mixture for stainless ... but ONLY with flux cored wire !

If you want to use a solid SS wire, you will need max. 5% CO2 in Argon, or Argon with 1-3% O2
Parent - - By CHEVYTOWN13 (**) Date 03-15-2004 18:08
SeƱor Buyle,

Can the SS wire, combined with either the 5% CO2 with Argon/Argon with 1-3% of O2 you mentioned, weld carbon steel effectively?

This place rocks man...

Parent - By jwright650 (*****) Date 03-15-2004 18:42
Hi Chevy,
Have you thought of using the 75/25 gas mix with a solid mig wire for mild steel(like ER70S-3 or ER70S-6)? Save your SS wire for SS, that stuff is too expensive to waste. Also keep in mind that SS and mild steel have different thermal expansion coeffients, and when fabricating, you should allow for that difference in expansion. (.0000065/degree for mild steel vs .0000099/degree for stainless steel)
just a few thoughts,
John Wright
Parent - By TimGary (****) Date 03-15-2004 21:15
Hey Chevy,
You're getting some good replies, but it seems kind of sporadic, so I'll put in my two cents...
Yes you can weld the stainless exhaust with SS solid wire and 75/25 gas, BUT, it will look like crap because the edges of the weld won't tie in very well with the pipe and the arc is hard to control for making an even bead. When MIGing SS, I like to use 98% Argon / 2% Oxy because it works a lot better.
So, yes, it would be a good idea to get a small bottle of 98/2 for MIGing SS to SS. And, no, you won't have to put anything on the weld to protect it.
Keep in mind though that the natural anti-corrosion properties of the SS on the inside of the exhaust pipe will hold up better if you purge the inside of the pipe before and during welding. Usually, pure Argon is used for purging because it's cheaper, but that doesn't mean that you HAVE to get a third bottle. You could just attach a "Y" splitter to your 98/2 hose and purge with it.
Also, yes, you can weld mild steel with the 98/2, BUT, it will look like crap because the edges of the weld won't tie in very well and the arc is hard to control for making an even bead.
For the SS to CS gate weld, use 309 SS wire and 75/25, and yes, you will have to put a protective coating on the weld to keep it from rusting.
Another thing to keep in mind when welding SS to CS steel is that there is a side-effect called dissimilar metal electrolysis. This causes the weld joint between the two dissimilar metals to corrode faster than the rest of the weldment, or in this case, gate. That doesn't meant that your gate is gonna fall apart at the seams right away, but if you're using thin wall tubing, it might not last longer than a year or two.

Good Luck!
Parent - - By GRoberts (***) Date 03-15-2004 20:19
Actually, you can effectively join stainless steel components with solid wire GMAW and 75/25 argon/CO2 shielding. However, it will not look as nice (it will be more discolored- but you can also get rid of it) or have as much corrosion resistance as a 95/5 argon/CO2 mix or a 98/2 argon/oxygen mix. Mild steel can be welded with any of these gasses. If you wan't to use spray mode of metal transfer though, you wan to go with a gas with a lower CO2 content (not 75/25). If all you do is short circuit mode of metal transfer, and you don't need optimum corrosion resistance from the stainless steel, or mind the discoloration, 75/25 would work fine. The 309 wire mentined is recommended for welding carbon steel to stainless steel because it is higer alloyed and won't form martensite, which might crack. If you are just welding 304 to 304, the less expensive 308 wire should work fine.
Parent - - By CHEVYTOWN13 (**) Date 03-16-2004 16:59
JW...those part numbers you gave ER70S-3, ER70S-6, the one that WG gave E-309L....Where can I find references to these? I'll look in weldreality's site to see if I can match any of these numbers for some info...

Thanks a ton Tim. You hit it right on the spot.

Although...the best thing about a question taking different avenues is that you learn something new everyday. Well, I try to learn some of this stuff. Some of it is over my head, but, it's all good. Can't tell ya, since starting welding 8 months ago, I can't thank all you HOMETOWNS from AWS forum enough...

Roberts, sounds like it's doable(sp?). Although, it's a rather heavy gate/door made out of 1x2 inch 16gauge tubing. It's 80 inches in height and 36 inches wide. Fellas, if there is going to be corrosion I'd rather stop being a lazy cat and take the time to switch the cable liners/ roll of wire and chug along that 150 bottle. Gotsta think first class alls the times man...

Learn sometin new ever day...

Gracias to all you hometowns that helped out...

Parent - - By jwright650 (*****) Date 03-16-2004 18:24
The ER70S-3 & ER70S-6 are solid mild steel GMAW electrodes. E309L is a type of 309L stainless steel wire. We don't fool with a lot of stainless here, so I don't have very much experience with it as these other guys do.
GR and Tim have valid points about the mode of transfer being something to consider when choosing your gas, something that I didn't really think about when I mentioned it.
We have welded SS plates to CS pipe and had problems in highly restrained weldments cracking due to the difference in rates of expansion/cooling(coefficient of expansion). I mentioned it just so you would be aware.
I would have thought your welding supply shop would have been more helpful in selecting a gas or wire.
John Wright
Parent - - By welder_guy2001 (***) Date 03-17-2004 03:09
Is it really a big deal if it's just a 18 ga. SS exhaust? Is it a big deal if it's a 1"x2" 16 ga. gate that probably weighs less than 100 lbs? If it's a pressure vessel, ok. If it's a structure that's been engineered to handle a certain load, ok. But this is garage work!
Parent - - By CHEVYTOWN13 (**) Date 03-17-2004 17:07
Don't know what your problem is bud, but take a hike homes. Don't need your mouth right now...

JW, thanks a ton man. You got me going in the right direction.

I'm going to buy the small bottle with appropriate gas mixture, SS wire and do up my bro's exhaust. And do the appropriate with the CS gate to his new crib.

Next round is on me!

Parent - - By kam (**) Date 03-17-2004 19:56
Hey Chevy
Here's my two cents. I work for an exhaust manufacturer and we use both 98/2 oxy and 95/5 co2. My personal preference is the 95/5...reason being ....98/2 is more prone to burn through due to the characteristic of its penetration pattern. It has a deep and narrow center column in the center. The 95/5 gas gives you a shallower and wider center penetration pattern. Both will get the job done but given the choise I would go for the 95/5. Also stick with a short arc transfer unless you have a good tight fitup....then you can go with a spray. Also unless you are doing a butt joint then there is no need to purge the tube with argon. Of all the different produces we produce there is nothing setup with a inner purge. Thought that was kind of odd that we didnt purge the inner tubes when I first started work here but have seen nothing wrong with the cross sections that I looked at in the lab.

Also...If anyone is interested in buying some cored 309 .045 wire and doesnt mind coming and getting it I can get you a good price on some. I think I have about 400#'s sitting around that I was told to get rid of. Its good wire (about a year old). I cant use it because we switched brands and quality folks told me to get it out of the shop. I live in northern Indiana...first come first serve. Think I might also has some 409 sitting around that I cant use either...its about 3 yrs old...about 500#'s.


Parent - By CHEVYTOWN13 (**) Date 03-18-2004 17:22
Long time no read hometown.

By the way Kam, I lost your email by accident.

I appreciate your advice homeboy. I swear I can't thank this place enough...


Parent - By welder_guy2001 (***) Date 03-18-2004 03:08
and a hike it is...this place is boring anyway
Up Topic Welding Industry / General Welding Discussion / Gas/stainless steel 304/carbon steel

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