Copper sulphate solution - about one teasponful per cupful
of water plus a few drops of battery acid.
Scrape surface clean and apply with a Qtip. Carbon
steels will almost instantly develop a bright copper sheen.
Stainless steels will remain unaffected.
The solution will work without the battery acid
addition but the action is much slower.
Color alone is a good indicator. Stainless drums are generally not painted
and have a somewhat frosty silvery appearance. They are also not magnet,
although if they're cold worked enough they can be slightly so. Some of
them, such as those used for nitric acid, often have steel bands located at
roughly one third of their lengths from each end, so if you check with a
magnet, be certain you apply it to the drum, not any hardware attached to
them. They're very costly if purchased new, in the hundreds of dollars as
I understand it. I recall that the deposit for the one I used to get
containing nitric was $400.
I know that after machining SS the heat creates a martensitic structure that
does not allow for magnetic alignment. so I believe that once heated and
immediately quenched ( maybe with compressed air) SS will have no attraction
to magnet. Regular carbon steel will still maintain some magnetism.
Open to correction
I'm having a little trouble with the idea that machining creates enough heat
to make such a change. Transformation takes place at quite high
temperature, typically red heat.
Yep, but that's not the point. One isn't checking to see if the drum is a
magnet. The inspection procedure is to determine if the drum is
*magnetic*, which would sort out steel from stainless. Dead annealed, a
steel drum is still very magnetic. A stainless drum (300 series stainless)
would not be.
AFAIK, ferrite is magnetic and martensite will retain magnetism (hence
magnets made of hard steel).
If austenitic stainless does indeed form martensite on work hardening, that
would explain the increase in magnetism.
AFAIK, heating any 300 series stainless, quenched or not, will only
effectively anneal it, as with mild steel (correct me if I'm wrong).
"California is the breakfast state: fruits, nuts and flakes."
When you work-harden 300 Series stainless, some austenite is converted to
martensite. This is what makes work-hardened 300 Series slightly magnetic.
There are special, modified versions of some common 300 Series stainess
steels that are formulated specifically to prevent them from becoming
magnetic upon work-hardening. These are intended primarily for wire-drawing,
where the reduction in section is extreme and the resulting magnetism can be
a problem in some applications. These special grades get their non-magnetic
properties from very small additions of copper to the alloy.
Heat treating 300 Series stainless, in general, will do nothing but anneal
it. There are some minor exceptions that you can read about with a Google
search. You won't get significant hardening with *any* 300 Series grade from
heat treating, however.
The easiest way to tell if a steel drum is stainless is by testing it with a
magnet. Any carbon steel and any common alloy steel that might be used for
making drums will be very magnetic. No stainless used to make a drum will be
more than very slightly magnetic. There's no mistaking the difference.
Take a grinder or sanding disk and sand to bare metal. Put water on the
ground surface and see if it rusts. You might have to wait for some time.
If no rusting for a couple days then use a magnet to check for magnetic
attraction. If it is a 300 series stainless it will not be attracted to the
What makes you think they are stainless steel?
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.