TIG welding stainless steel and steel together

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I would need to weld a stainless steel with a steel piece together, my first question is can it be done fairly easily?  I was reading the TIG welding calculator on the Miller website and I saw that they say to add 10% amperage for mild steel as opposed to SS.  What to do then?  The pieces I need to join are a stainless steel turbo flange with a steel turbo turbine housing.Thanks in advance for any help you guys can provide.
Reply:Why are you welding a flange to the housing? The housing should already have a flange on it...does it not? Did you cut off the flange for a different application? Yes, you can weld it as normal. If you're welding that to the cast housing, it may prove tougher for you.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Originally Posted by MicroZoneWhy are you welding a flange to the housing? The housing should already have a flange on it...does it not? Did you cut off the flange for a different application? Yes, you can weld it as normal. If you're welding that to the cast housing, it may prove tougher for you.
Reply:You're comment about 10% more heat for carbon steel may be true since SS has much lower thermal conductivity the heat stays concentrated and less is needed to melt a pool.  But why even worry about this, particulary if you have a variable current control foot pedal?  Just apply whatever current is needed to melt the proper size bead.The important thing to think about is the metallurgy of welding SS to carbon steel.309 SS filler is recommended for welding 300 series SS to carbon steel.  The 309 will help provide a weld chemistry that remains non-hardenable and ductile, thus helping to avoid the formation of hard and brittle martensite and weld cracking that may occur from simply fusing SS and CS.Not to say that the SS/CS joint will always be brittle and crack, it depends on the alloy content of the base metals and the mixture that ends up in the weld.  With very low carbon content, in a plain steel, you may not have a problem, but 309 is good insurance.
Reply:i've done a couple of external wastegate conversions. the turbine housing is definately cast- whether it's steel or a high nickel iron is another question. both the ones i've done machined like cast iron but welded VERY nicely for a castinginconel 625 was the filler i was recommended to use (on the basis that the housing was likely a nickel cast iron). managed to blag some (inconel's not cheap!) for the first turbo but i used 309 for the other. both housings welded nicely and have survived the vibration and heat cycles wellany comments Pulser? from searching around the most likely candidate for the turbine housing was a Ni-resist ductile iron (around 40% Ni ) IIRC
Reply:My first choice would be a 309L, with inconel being a second.  I really like 312 as my primary choice if base composition isn't known, but it doesn't lend itself well to extended service high heat use.Pulser hit the nail on the head though.  Just be leery of the dilution factor.
Reply:I think I'll just go with a T3 housing with no internal wastegate.  I'd hate to ruin a brand new turbine housing.
Reply:I agree with Pulser regarding the 309, but I've had good success in the pass with "buttering" the steel with a layer of 309, and then welding the interface with ER308L.  Improved corrosion resistance.I r 2 a perfessional
Reply:Originally Posted by kbnitI agree with Pulser regarding the 309, but I've had good success in the pass with "buttering" the steel with a layer of 309, and then welding the interface with ER308L.  Improved corrosion resistance.
Reply:Zap,Been busier than a one-armed Tig welder.  Got some time between projects and a new high-speed connection.  Good to be back.  I r 2 a perfessional