Repairing with stainless

[227bhp]

I'm patching up an old car, cutting out old rust and welding in new metal. Is there any reason why I can't use bits of stainless steel for my patches? Some of them are going to be hard to rust proof fully from the inside and I hope using this will prolong it a bit more.
Is there some strange metallurgy rule I haven't heard about?

[Scotty2]

Welding stainless needs special wire or TIG. The bond between the two will be brittle and prone to rust at the weld area due to the difference between the metals. Better use weld through primer and protect with Bilt Hamber type corrosion inhibitor products.

[Russwhitehouse]

As Scotty has rightly said above. Caution is always advised when welding/bonding dis similar metals due to potential electrolysis and cathodic corrosion.

[TooMany2cvs]

It's not unheard of - there have been people selling stainless repair sections for door and wing bottoms for DSs, that I know of.

For a structural component, though? Wouldn't have thought so.

Anyway, isn't SS quite heavy compared to mild?

[GAjon]

If you can get hold of some, use stainless ferretic grade 1.4003 (3CR12) it's a grade that's almost mild steel with stainless corrosion resistance properties.
A lot of ducting companies use it.
Weld with TIG if you can, if you can get to both sides of the weld, do non penetration welds and weld both sides, if not try and get an inert gas purge behind the weld and full penetration welds.
As said the area local to the weld on the carbon steel side will be the weak area but if it's for areas prone to corrosion anyway a weak weld area is going to be better than rust?

[lowdrag]

Completely off topic, but may I recommend Zanussi? When a Jaguar Mk 1 was pulled out of a garage after 25 years slumber it was pretty rotten. Being poor, the owner used the carcass of the old washing machine. Still in good order to this day, and that's more than 20 years! But seriously, with modern rust inhibitors I can't see a problem with ordinary steel. My car only required new floor pans after 25 years hard use, and that was because the welds weren't properly treated. The rest of the car was fine. Methinks thou dost worry too much?

[steveo3002]

you can get zintec sheet for this job , coated steel that resists rot better than plain stuff

[sassanach0]

i have a mk1 granada coupe into which i welded stainless steel sill closers back in 1989 using ordinary mig wire.guess what its still fine......

[grumpy52]

steveo3002 said:

you can get zintec sheet for this job , coated steel that resists rot better than plain stuff

If you use zintec do it in a well ventilated area or use an oxygen mask .