How am I doing?

[Andrew D]

Mhhh, don't know what happened, it worked yesterday. Anyway, here's a thread I started which segued into an electrolytic one [as threads do ] which gives some good reports/techniques.

http://www.mig-welding.co.uk/forum/threads/small-rotary-table.57597/

Can't find the BIG one I meant to link to now...... , maybe someone else will put it up.

Water, soda crystals, a battery charger, a bucket and some leads and plates / terminals and that is about it? I might take this car project a little further. Do you think a rear beam axle will fit in the bath?

 

[chris y]

Great read that Carlton. Brave man indeed. So I take it there is no dissimilar metal corrosion between stainless and mild steel. I always thought stainless needed particular feed material then mild steel.

There is no dissimilar metal corrosion because of course you need to paint your work so there is no electrolyte (water) present on the metal surface. I have uncovered some work done quite a few years ago and there is no corrosion.
Left unpainted there would be fast corrosion

 

[p0689109]

I thought some metals did not necessarily need water to corrode as their constituents were enough to cause a reaction. Still thanks for info as every little bit of info helps.
Of course when we repair mild steel with mild steel and take all the necessary precautions of primer, rust preventative, paint etc some still manage to rust, mainly because of the quality of the steel used in the first place!

 

[chris y]

You need oxygen for rust, its oxidation of course, but electrolytic corrosion of dissimilar metals needs an electrolyte as far as I know. A good coating will keep oxygen and water out so should prevent corrosion.

Its all very well me talking about theory, it doesn't mean much if it doesn't work in the real world but from what I've seen of my old work the work lasts and that's good enough for me.

Low quality steel which repair panels will be made from will be difficult to prevent rusting because the slightest porosity or damage will let rust start and it will rampage through the crap steel in no time.
Of course I've seen rotted out repairs after a year or two as most of us will have, with repairs very good painting and sealing is vital even if using corrosion resistant steel because the welds and the area around them on the original panel will rust in no time.

 

[p0689109]

What I was wondering is that welding works by fusing the metal together but when the metals are of a different mix of atoms and therefore their melting points and granular structures are different then although the welds might look ok do we know, or in fact, can we convince ourselves that the weld will hold in say a crash situation. As an example there are many glues that you can use that will stick two things together and in normal use seem strong but when it comes to the full test they fail because the bonds are not full as opposed to skin deep as it were! Just musing that's all!!