[LMB] Fwd: Re: [OT] AKICOTL: metal cutting

Baur baur at chello.at
Sat Oct 13 09:14:25 BST 2018


Am 13.10.2018 um 02:24 schrieb Joel Polowin:
> Rachel <anglerfish at gmail.com> wrote:
>> From: Joel Polowin <jpolowin at hotmail.com>

> I know that stainless-steel T-pins exist, though I haven't found
> a local source.  I tried buying some on-line, but they turned out
> to be regular plated T-pins.  (Test: deeply nick the surface,
> then put between two sheets of toilet paper in a small dish.
> Thoroughly wet with water, but don't immerse; it's important that
> the setup have plenty of oxygen.  If the pin is just plated, it will
> rust rapidly where it's nicked, staining the paper in less than
> an hour.  Real stainless won't change visibly.)

that is not entirely correct .. it depends on the type of stainless steel ..

this comes from my experience in selling boating equipment .. the 
maritime envrionment with salt spary is one of the most corrosive you 
will regularily enocounter ..

there is corrosion resistant stainless steel .. often called SAE304 or 
A2 or 1.4301 ..

it resists rusting in a maritime environment - it might however, 
especially when its surface is not polished or becomes scratched may 
develop slight surface rust - this does nothing to detract from its 
mechanical properties, as there will only be a VERY thin layer of 
localised rust, it willo not go doen into its strucutre. a application 
of a polishing papaer usually removes that layer ..

and there is acid resistant stainless steel .. this one will not start 
to develop surface rust, even in environment more corrosive than sea 
water .. (chemical works with acid, for example)

this is usualy called SAE316, A4, or 1.4432 - steels of this and related 
types are often used as chirurgical stainless steel

we sometiomed had complaints about surface rust .. and that was my usual 
explanation. The reason why 304 or A2  was used for some applications 
is, that it can have better mechanical and welding properties for these 
applications ..

polishing up the surface will remove that surface rust and will prevent 
reoccurance in many cases ..

> I spent perhaps
> more time than I should have in reporting the seller to the site,
> then disputing their claims that "No, really, it was stainless when
> we sold it!  And why did you nick the surface, that's why it rusted!
> And stainless is supposed to do that!"  But eventually I got my refund
> and the seller had to remove that item from the site.

so - see above - the seller might have been correct and only gave in to 
get rid of you ..

after all, you scratched the polished surface

servus

markus

> 
> Joel
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