Quick welding question?

[yellow90tsi]

is it OK to weld a piece of SS (stainless steel) to a piece of mild steel? Im not really worried about the look but the integrity of the weld is what i am more concerned about. Also i would be using .035 wire with a 75/25 gas mix. Thanks guys.

 

[SinaiTSi]

Yes, that's fine. "1slocolt" (on these forums) is really great with welding, and he says it's ok.

 

[yellow90tsi]

sweet, i cant wait to get welding. Thanks

 

[perley03]

i am a welder.....you CAN do it to a point....the thing is stainless steel has added compounds to make it "Stainless", or rust resistant. these compounds are actualy different mixtures of elements, like zinc, nickle, tungsten....you get the point. anyways these two types of metal, cold steel and stainless steel expand and contract at different temperatures. if you get it hot then cool it very fast it will expand and contract and cause the weld to disform, or crack. afterall, the weld is actually stronger than the steel itself, therefore it will crack around the weld and you will have an exhaust leak. if you were to weld the two together, have someone TIG weld it and have them use stainless filler rod instead of a mild steel because the stainless will blend with the mild steel pipe and it will not be as prone to cracking. if this confuses you email me and i will explain it in better detail. sorry about the long post guys.
shawn

 

[perley03]

also you said you were using 75/25 mix of gas....i would use 75% argon, 10% helium, 15% CO2 if you were to mig it...also use stainless wire. .035" sounds too thick also, try around .020" and it would be easier to weld if you cant get someone to TIG it for you.

 

[jarredsyxx]

I would also suggest a tig weld... we work with a lot of stainless in our plant ... the plates that stamp CD's and such have to be because the plate itsself is water cooled.. but its much cleaner and definately easier to work with because stainless gets so hot as they have said in the previous posts... find a buddy maybe that works at a factory ...or just call any machine shop.. Im sure they would do it for next to nothing...

 

[yellow90tsi]

Well the part that is stainless is a 3" flange for the downpipe. And then the piping is mild steel. So do u think that will get hot enough to make a difference? I was going to wrap it also . Worst case i can just take it somewhere and have them TIG it on there. Thanks for the info guys i appreciate it.

 

[perley03]

take it to a shop and have them tig it....cost like $40 max to do it. if its on the downpipe i wouldnt worry about it, but just to be safe i would tig it. i think the wrap holds in the heat (correct me if im wrong, but thats why race cars use it) so it would be hot longer and cool slower than it not being wraped, so i think you will be fine there.

 

[GVR4592]

It can be done, you want to use 309 stainless filler material. CO2 in the shielding gas should be kept to an absolute minimum, as it greatly affects the corrosion resistance and can lead to a weaker weld, most stainless mig welding is done with a helium-argon mix. If you use shielding gas with helium you usually have to increase wire speed slightly, for some reason the arc seems to be a bit hotter with helium.

Somebody suggested above that you should use some thinner wire, I agree. Although I've never seen .020 stainless wire, I usually use .025 or .030 when welding exhaust's.

It's probably more cost effective to have a shop weld it for you instead of buying the wire and the shielding gas for one weld.

 

[patty AT forge]

I say go with TIG, but make sure they back-purge the weld. People like to take shortcuts on quick little side jobs like this.