[TheForge] last project

Thu Jun 5 03:08:03 2003

Ya know it just occurred to me that what your doing isn't really
electropolish its passivation.  We passivate anything we heat, actually what
happens when you weld is you burn off some of the nickel and chromium from
the stainless and float the iron which turns colors to the surface.  Duh
somedays I should engage the brain.  What was that Dain Bramage.  The answer
is nitric acid, and electricity.  I have done that but I use a scotch brite
pad a grey one not a red one.  I have an inverter 300 amp welder that goes
0-50 v and 0-300 amps I use it for a power supply to do that but I have
never used it on a weld per say we have "scrubbed" the inside of finished
tanks where the weld zone shows through by causing oxidation. Or just plain
heat marks. Passivation is the removal of iron from the surface to prevent
discoloration.

----- Original Message -----
From: "Paul Hewitt" <[email protected]>
To: <[email protected]>
Sent: Wednesday, June 04, 2003 11:42 PM
Subject: Re: [TheForge] last project

> Okies good answer, must of my TIG work on stainless finds its way to Wafer
> fabs (silicon computer chips) so it never see's the weather.
>
>
> ----- Original Message -----
> From: "RIES NIEMI" <[email protected]>
> To: <[email protected]>
> Sent: Wednesday, June 04, 2003 10:01 PM
> Subject: Re: [TheForge] last project
>
>
> > on 6/4/03 6:12 PM, Paul Hewitt at [email protected] wrote:
> >
> > > Just curious but you actually spend the time to EP the welds, I just
> take a
> > > small stainless wire brush and brush them hot as soon as I am done
> welding,
> > > takes the color right off.
> >
> > I have found that even though the ss wire brush makes the weld look
clean,
> > in time, particularly outside, the welds still discolor. The heat
affected
> > zone has the chromium burned off, or recombined, or something, and so
> unless
> > you etch it back down to pure ss, it will turn kinda purpley brown for a
> > little ways around the weld. Of course, this depends on the size of the
> > stock and the amount of heat you put in it.
> > I have a bridge I built last year, 40 feet long and 12 feet tall,
imagine
> a
> > covered bridge, but the cover is a skeletal salmon made from 3/8" round.
> > Because it was so big, we couldnt electropolish it, and I didnt have the
> > little mini polisher then, so we just wire brushed it. It looked great
for
> a
> > month, but now, a year later, every weld looks kinda dirty. Not blue and
> > purple anymore, just discolored.
> >
> > I have an electropolish tank, my friend owns a
> > > buisness and he mixes up his favorite concoction of acid and sends it
> down
> > > to me and says add X amount of water, his process is supposedly so
> secret we
> > > only get MSDS sheets I have no idea what is in it, but its BAD LOL.
He
> does
> > > hold a patent, and I do know his stuff works better than any other I
> have
> > > tried, plus I don't have to deal with the garbage I simply take it to
> him
> > > end of story he runs it through the reclaimer and that's it.
> >
> > Wish I had someone like that- although mostly I design things to fit in
> the
> > tank, or components that fit in the tank and are site welded together
with
> > the minimum amount of connections.
> >
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