Clueless non-metalurgist seeks "short list" of alloys for resilience/anti-corrosion use

I am mostly clueless here, and need some basic hints.
Steel materials properties are simply too complex
to be modeled easily. First-hand experience is clearly
I must select a steel alloy, but I was a physics
major, so I am lost in an endless twisty maze of
stress-strain curves, Young's modulus numbers, and
conflicting tensile strength claims.
All I need to do is to narrow down my choices to a few
commonly-available non-exotic commodity alloys, and then
rationalize costs against strength.
The goal is to create a simple flat "pry bar" hand tool
that will be no longer than 7 to 10 inches, and no wider
than 1 to 2 inches. A minimum thickness of 11 gauge "seems
reasonable", but thicker would not be a problem. A dull
edge will need to be ground on the "blade", and this edge
will do all the prying. (The "edge" is to allow the
part to force open narrow gaps.)
I understand laser-cutting prototypes and then stamping
production units. Drop-forging is something I have
only heard of, and I have no idea if it is economical
for production runs in the hundreds, rather than hundreds
of thousands.
I looked at my own tools for good examples of the kind
of stress-strain and corrosion-resistance I need, and found:
CIRCA 1977 STANLEY THIN CROWBAR (roughly 11 gauge)
Made from a high nickel alloy, but has some surface rust.
Clearly made from sheet stock, and then formed into a
"squished S curve" to make it a "crowbar".
A forged part, said to be made of 4620 alloy.
Another forged part, said to made of 4140 alloy
and then coated to avoid corrosion
These are said to be made of 4037 and 4137 alloys
Other Alloys that have been mentioned in the course
of my research include 4130 and 6150.
Specific "corrosion resistant" alloys have also
been mentioned, including 4340, 4320, and 4620.
My problems are narrowing down choices to find the
optimal trade-offs between:
a) Good resilience/stress-strain, as a pry-bar that
bends is useless.
b) Non-salt, non-acid, "normal outdoor exposure"
corrosion resistance, as powder coats will abrade
off over time, and 3xx 4xx "stainless steels" appear
to both lack the required strength and are too costly.
(A high-strength stainless steel would be "excellent",
if it were affordable, but the communist Chinese appear
to be buying up so much steel that I'm not sure we
can afford "stainless".)
c) Cheap to make in 100s, maybe a thousand per batch
at the most. I know that tooling for stamping would
be less than $2K for a part this simple, but the
stamping company appears clueless about materials,
and the laser-cutting shop thought that 11 gauge
304 stainless was a "good choice", until I had them
cut a sample, and bent it into a curve with my
bare hands before their eyes.
So, any clues for the utterly clueless?
I had hoped to contract out:
a) Cutting the part from 48" x 96" sheets
a1) With a laser cutter, or
a2) By stamping
b) Remove burrs, grind the "edge", and polish
a smooth finish on the surfaces
c) Tempering? This is where things get scary,
as the failure mode wants to be "bend before
shatter", but bending is exactly what we
want to resist, up to and including putting
one's foot on the pry bar, and stomping on
it when trying to pry apart nailed wood.
But drop-forging is not out of the question, if this
is a "must".
jim (
Reply to
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Thanks, that site has some good general info, but I overdosed on "knife" related info when reading the archives of rec.crafts.metalworking. Those folks are really into sharp objects. :)
There is no need for a "blade edge" on this. From what I have read, all "knife" alloys will consistently be more brittle as a result of being able to hold a "sharp edge".
I'm just looking to make a strong but flat crow-bar from "standard stock" without a lot of fancy treatment.
Reply to
Seems like you've done you homework
why not just copy the
11 gauge is pretty thin but I gues its ok since the tool is rather small
are you sure its high nickel?
the alloy steel 4xxx are more for wrenches & sockets etc
been mentioned, including 4340, 4320, and 4620.>>>>
I don't think of these as particularly "corrosion resistant" alloys, if they were they wouldn't need plating
One possible choice would be 301 partial hard to start additonal coldworking of mfg would boost the the yield strength (in the zones that were worked)
you want a material with a relatively high yield strength plus some yielding elongation before ultimate.
Maybe a spring steel & a heat treat.
Phosphate coat & paint
Reply to
Bob K 207
Just to throw a monkey wrench into your works... Enderes uses 1078, for everything, and they make the best rough-use tools to be had. :)
If this really is a "production run" and not a homework assignment, hire yourself a metallurgist. :/
(you can find them at
Alvin in AZ
Reply to
No, I have not been a student for several decades.
Did you ever consider that an insightful and specific answer might lead to a short-term contract to herd this thing through the laser-cutter, the stamper, the finisher, the powder-coater, and the rest of the cast of thousands required to make a simple object from metal? Didn't you wonder why I would post an actual e-mail address to the cesspool that UseNet has become since 1995? (james POINT fischer AT SIGN google POINT com)
I SAID I was clueless and needed help, didn't I? :) If materials selection is this painful, I can only imagine what pitfalls lie ahead in the attempt to make the material into a finished item.
I thought I was merely comparing the cost trade-offs of cold working 3xx stainless versus heat-treating 4xx stainless, but things started to get complicated when looking at both "tensile" and "yield" strengths, and got worse when I started getting quotes on the current cost of stainless steel in general.
So, name your favorite material, specify your processes, wait a week or so for prototypes to be made and tested, and the winner gets a nice little side-job. And I get this off my desk, where it clearly does not belong. I'd guess that any undergrad or grad student would be perfectly capable of being orders of magnitude better at this than I.
Reply to
Cool! :) Glad to hear it. :) That doesn't mean, you're not still learning tho right? ;)
Alvin in AZ
Oooo, I didn't call where you like to live a cesspool! :/
"kill files are for sissys" -alvin -and f@#$ them sissy forums too. ;)
Maybe you aren't familiar enough with it, but your post looks like the typical homework assignment we get here. :/ No offense but I ain't backin up on that one. ;)
I'm self-taught in metallurgy so I'm especially sensitive (maybe even too defensive?) about it. :/
Consult a metallurgist or you'll end up with a friggin heap of scrap. The worst case senario is, of course, a law suit. :(
Hire one and hope for the best? :)
Hope in one hand and sPit in the other and see which one fills up first? :)
Alvin in AZ
Reply to
From the dimensions you gave you would seem to want a very strong material which is why I directed you to the top hardness martensitic / precipitation hardened type alloys. The sorts of strength / hardness implied from your dimensions are all carefully heat treated and surface finished. What yield strength do you want?
Reply to
David Deuchar
The original poster wanted a stainless steel tool. I agree that a (carefully) chrome plated spring might do the job it is not what was asked for.
Reply to
David Deuchar
Yep, it's the same stuff he named off already too-> "low alloy medium carbon steels". :)
Alvin in AZ
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