What happens if you mig weld stainless with mild steel wire and Argshield.

Not that I'm planing to, but just wondered. Someone told me that some of the stainless leeches into the filler and you end up with a low grade stainless joint which doesn't rot but isn't shinny; Not that they'd know!

adrian

I don't know either but let's think about it. The heat from the weld melts the stainless and mixes it with the wire. It forms a pool that will move a bit but not much. If the joint is quite tight then you don't need much wire to fill the gap but if there is a big gap, there will be more mild wire in the pool.

The mixture "strength" of the alloy will depend on the amount of wire to stainless in the pool. I'd have thought that the "strength" would drop from 100% on the edge of melting to 0% if a lot of filling was done with the wire.

I seem to recall that you need at least 25% chromium to be rust proof. I guess it depends on what grade of stainless you start off with.

I've done it on my stainless exhaust and it's pretty much what you said. It's black but hasn't actually gone rusty.

I use stainless sheet to repair all my cars when doing patches. No probs and just ordinary gas and mild wire, one day I might try stainless wire.

I've used stainless wire and argon gas with a mig welder, no problems and really good welds.

Welder was a Sealey supermig 185

[Edited on 7/2/08 by stuart_g]

Welded my last manifold with stainless tube and mild steel wire and after a year no rust on welds.

Tried using stainless welding wire but it's stiffer than mild steel wire and welder drive was not up to it. Welds were absolute rubbish as of course is the mig welder!

Will weld next manifold with mild steel wire without any qualms.

While on the topic, why is it that nobody seems to be manufacturing spaceframe chassis in stainless steel? Wouldn't that be cheaper (in man-hours) than mild steel + coating x N? How do the two compare in terms of stiffness vs. weight?

Stainless is heavier, a hell of a lot more expensive and, from what I remember from comments in the past, prone to stress cracks.

It's a lovely metal to tig though

ATB

Simon

Cheers, Simon I knew there had to be a reason!

"Stainless" isn't one type of steel its is dozens or even hundreds everything from the "Stainless Iron" cr*p your kitchen sink is made from to very high strength steels used for the teeth on JCB buckets.. In short you have to have an idea what type your are welding.

With "stainless iron" you don't have too worry too much but with proper stainless steels you have to have a idea of the metalargy of the weld.