Welding stainless to mild steel

[abn]

My "Welder's Handbook" (Richard Finch, HP Books) states that Stainless can be Arc welded to non stainless steel...and then instructs to use the appropriate stainless rod to do so. If you can weld stainless to non, then why can't you just use a mild steel rod? The book doesn't mention oxyacetylene welding stainless to mild, is there a problem with that approach?

The context if you care to read:

I'm sleeving a surplus electric motor output shaft to a constant 3/4" (It was necked down to 1/2")and extending it. I cut a piece of some scrap that was given to me as it was already beutifully machined to 3/4" and bored it to an interference fit and pressed it on to the output shaft. After my work was complete I got the bright idea to check what material I used...a magnet revealed that the scrap was stainless and the motor shaft is magnetic. I'd like to weld the hairline joint between the shaft and extension, but need to pass it through a bearing bore so I have to bring it back down to 3/4"...can I do this with just an oxyacetylene flame and no filler?

Thanks for all the help and patience on this board!!!

[RGFaison]

ABN,
You can join them together using oxyacetylene and silver brazing wire.
Has good strength and is used when joining dissimilar metals. You will need to use the right flux for silver braze.

Russ

[JCHannum]

Just use a set screw?
If you weld a joint such as this, it is sure to warp. Silver solder is best choice, but warpage may also result. In either case, remachining will be necessary.
Stainless filler rod is required when welding stainless to steel. Stick and TIG are best, oxy-acetylene is tricky.

[firbikrhd1]

I never tried this, but a local welding supplier told me that a MIG welder using ER70S6 with Argon/CO2 gas would weld thin stainless such as that used in range hoods and that its done frequently. If that is the case, it might work to weld other stainless to mild steel. I wonder what the welds would look like and how strong they would be. Anyone tried this?

[steve schaeffer]

hey, i just made a sleeve for my compressor. i got a new motor that had a 3/4" shaft, old one had 1". because of the keyway, it is in essence split and it works fine. no welding required! kid tested, mother approved! my pulley had set screws.
steve

[jfsmith]

I did weld 440 to 1095 with my MIG (GMAW with ER70S6 and Super Argon Mix), great strong weld, had to grind things alot and then suffered some warpage. I recut the whole piece and made a knife out of it.


Jerry

[JCHannum]

You may be able to MIG stainless with mild steel filler, buy why? Joint will rust, and stainless in area of weld will also rust.