Stainless wire on carbon steel

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This is somewhat hypothetical or curiosity based.   I have some stainless steel repair to do today and will pick up a two pound spool of 308 wire for my Miller 252.   Let's say I need to weld some carbon steel before I finish the stainless work and I'm too lazy to change the spool back to carbon wire and back again (OK the lazy part is not hypothetical).    Will the 308 stainless wire work for regular carbon steel?
Reply:Forgot to add:  I usually have the 75 Argon/25 CO2 hooked up but will be using Tri-Mix for the stainless.
Reply:Get 309 instead...Commonly used for dissimilar metals so you will be good to go....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Good question about just using what's on the machine?  All the written work would say not to do it.  Would be interesting if the guys with coupon benders did some tests.
Reply:From ESAB's website,http://www.esabna.com/euweb/awtc/lesson5_18.htm"When the steels to be jointed are different metallurgically and chemically, the electrode is selected to provide a tough, crack resistant weld between the two steels.  For example, 304 stainless steel is frequently welded to mild structural steel.  Corrosion resistance cannot be part of the problem because mild steel is on one side of the joint with practically no corrosion resistance compared to the stainless steel.  If this weld is made with mild steel electrodes to match the mild steel side of joint, the weld metal would be enriched by the wash-in of chromium and nickel from the stainless side.  This intermediate chrome-nickel is usually hard and crack sensitive.  If the weld is made with type 308 electrodes to match the stainless steel side of the joint, the chromium and nickel contents of the weldment are diluted by the mild steel side of the joint to an intermediate level that would again probably be hard and crack-sensitive.  When welding mild steel to stainless steel, a proportion of 18% chromium and 8% nickel is desirable in the weld deposit to produce sound welds, with 17% chromium and 7%nickel being the minimum allowable amounts."So, using 308 filler metal to join two pieces of mild steel, or mild steel to common stainless steel(SS304), can result in a weld deposit with a diluted chemical makeup that is prone to cracking.  The resulting weld may have untempered martensite, which is an extremely hard and brittle structure.  Or there may be some temper embrittlement, depending on how long the weld takes to cool down.Temper embrittlement is a problem with alloy steels(like 4140) and tool steels that results from improper heat treatment or incorrectly using them at high temperatures.  The diluted weld metal chemistry from joining mild steel with 308 filler metals can wind up looking alot like these steel alloys that are sensitive to temper embrittlement.It's a crap-shoot.  The weld may be fine.  But if there is too much dilution with the mild steel, and/or the weld stays hot for too long, you may produce a brittle weld deposit that is likely to crack.  The catch is you won't know until the weld fails abruptly under load.309L and the other filler metal grades meant for joining carbon steel to stainless steel are enriched with alloying ingredients(Cr and Ni), so that when the weld is diluted with mild steel the resulting weld is still highly alloyed.  This avoids the whole issue.Bottom line, can you weld mild steel with 308 or other filler metals intended for joining stainless steel?  Yes.  Is it safe and reliable?  Not always, and there's no way to tell with the naked eye whether or not a weld will be defective and fail.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Great info!  That's what I was looking for, thanks.
Reply:Originally Posted by A_DAB_will_do309L and the other filler metal grades meant for joining carbon steel to stainless steel are enriched with alloying ingredients(Cr and Ni), so that when the weld is diluted with mild steel the resulting weld is still highly alloyed.  This avoids the whole issue.
Reply:how about regular wire on stainless steel? is that possible?I apologize in advance for my inexperience.
Reply:Originally Posted by almachow about regular wire on stainless steel? is that possible?I apologize in advance for my inexperience.
Reply:Great info in post 5. Thanks.IW Local 580 NY, NY