View Full Version : SS to mild steel??

12-28-2015, 03:50 AM
I need to weld some SS bolts to mild steel. I don't know what type of SS as its a hardware store purchase.
Any idea what type of SS is typical?
What wire type do I need?
Shielding gas type?


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12-28-2015, 04:06 AM
309, perhaps 309 LMo or whatever is locally available.
same gas you use for your SS welding now.

grade of SS does only matter for a slight part here, but it probably is marked as either A2 (304) or A4 (316).

12-28-2015, 04:11 AM
Thank you!

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12-28-2015, 12:54 PM
If your mig welding I bet you could run the same setup for mild steel. Make sure the bolt is Bare stainless without a coating on it or remove the coating yourself

12-28-2015, 01:20 PM
75/25 MIG shielding gas with standard solid wire works fine.

12-29-2015, 10:31 PM
Thanks guys. I'm going to use mig. I'll def clean the snot out of both pieces.

12-31-2015, 10:18 PM
Most likely 304.....Just curious though.....Why not just use steel bolts? Typically Stainless bolts and nuts
can have a galling issue where the Grade 8 bolts won't..... If your thinking about the NO RUST faculties of the stainless they will probably lose
that when you mig weld them

01-01-2016, 11:13 AM
309L filler wire is correct.

01-01-2016, 02:26 PM
Could possibly use G8. Although I prefer ss. Everything around the area will be painted including the weld zone but the shank and threads will be exposed to severe conditions.

01-01-2016, 02:41 PM
I have a customer that insists I use stainless fasteners on their assemblies. There are dozens of 1/2-13 stainless nuts welded over each assembly. Everything else is steel, then hot dip galvanized, even the stainless nuts end up getting galvanized... What can I say, I'm dealing with architects on this one :dizzy:

I MIG weld them, use standard wire and gas. Using stainless filler and gas won't help you at all. I was once told, and I'm not sure if it's 100% accurate, but there's something called bimetallic corrosion. When two dissimilar metals are in contact, the least corrosive of the two metals (stainless steel) corrodes at a faster rate, and the more corrosive metal (steel) actually corrodes at a slower rate. I tried researching this once, and I found sources saying they have to have a current running through them in order experience this, and other sources stated that physical contact was enough to form an electromechanical bond. I saw some example pictures in which aluminum plate was corroded all the way through in less than 2 years just because it was bolted to a steel plate.

01-01-2016, 03:48 PM
I build roof racks and other things with removable options, and I use stainless nuts for mounting. I weld them on with steel MIG, and then it all gets powder coated. So the only exposed metal is the stainless threads of the nut. I've got stiff that's been out in the NW elements for 5 years now and no problems at all. Important thing is to be sure to always have a little anti-seize on the threads to alleviate the mentioned galling issue stainless has.

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01-01-2016, 03:49 PM
Just me....

Yep, that's what I'm trying to achieve. In Cali now, but I'm a P-town boy. :-)

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