Further to my last post (Material for clamping wedges), I've now determined
that the original parts were case hardened steel.
I will be making the parts up soon, but I don't know what grades of steel
can be case hardened; the commonly listed steels for case hardening are EN3B
(SAE 1017 or 1022) and EN32 (SAE1016), but these are not readily available
in small quantities (600mm / 2'). I can obtain EN1A (free machining mild
steel, no direct SAE equivalent) or EN8B (closest equivalents are SAE1040
and SAE1038) from model-engineer-friendly suppliers, but I am unsure if
these can be case hardened. I plan on using Kasenit case hardening powder to
harden these parts. Can anyone enlighten me?
Martin.
--
martindot herewhybrowat herentlworlddot herecom

"Martin Whybrow" wrote in message
news
Further to my last post (Material for clamping wedges), I've now
determined
that the original parts were case hardened steel.
I will be making the parts up soon, but I don't know what grades of steel
can be case hardened; the commonly listed steels for case hardening are
EN3B
(SAE 1017 or 1022) and EN32 (SAE1016), but these are not readily available
in small quantities (600mm / 2'). I can obtain EN1A (free machining mild
steel, no direct SAE equivalent) or EN8B (closest equivalents are SAE1040
and SAE1038) from model-engineer-friendly suppliers, but I am unsure if
these can be case hardened. I plan on using Kasenit case hardening powder
to
harden these parts. Can anyone enlighten me?
Martin.
--
martindot herewhybrowat herentlworlddot herecom



Both of the two, SAE 1040 and 1038, can be hardened without case hardening,
although you'd be limited as to their hardness because of the relatively low
carbon content, which is indicated by the last two digits. 1040 has .4%
carbon, and 1038 has .38% carbon, each of which are classified as a medium
carbon steel. If your parts are subjected to considerable shock, that may
not be a good choice, for you might have need to keep the cores dead soft,
but if you're looking for something with considerable resistance to
mushrooming, and to surface deformation, each of them could prove to be a
good choice. Case hardening will provide a harder surface than you'd
otherwise expect, and the cores will be harder than if you made parts from
lower carbon content material, or mild steel. If your parts are,
indeed, clamping wedges, and don't get subjected to impact, they would
likely turn out all the better using the medium carbon steel. Be certain
to draw them back after heat treat to eliminate stresses.

Harold

Low carbon steel (e.g., 1020) is usually used for case hardening,
because you usually want a very ductile core inside the hard, brittle
outer surface. That way any cracks in the brittle surface do not
propogate through the whole part. The quench gives the greatest
hardness to the steel that is highest in carbon and nearest the
surface.

The link below shows EN1A has .15% (max) carbon and is similar to 1215.
It also has .07% phosphorus which acts like carbon to some extent.
With ~.2% carbon-equivalent it should work well.

links:
http://www.gulfstreamsteel.com/Excel%20spec%20files/comparison%20of%20USA%20standards%20(chemistry).xl s
http://yarchive.net/metal/case_hardening.html

David

"Martin Whybrow" wrote in message
news
Further to my last post (Material for clamping wedges), I've now
determined
that the original parts were case hardened steel.
I will be making the parts up soon, but I don't know what grades of steel
can be case hardened; the commonly listed steels for case hardening are
EN3B
(SAE 1017 or 1022) and EN32 (SAE1016), but these are not readily available
in small quantities (600mm / 2'). I can obtain EN1A (free machining mild
steel, no direct SAE equivalent) or EN8B (closest equivalents are SAE1040
and SAE1038) from model-engineer-friendly suppliers, but I am unsure if
these can be case hardened. I plan on using Kasenit case hardening powder
to
harden these parts. Can anyone enlighten me?
Martin.

Any mild steel can be case hardened.

bw wrote:
Any mild steel can be case hardened.

Can leaded steel be? I've never tried it.

--
Artful Bodger
http://www.artfulbodger.net

"bw" wrote in
:




Any mild steel can be case hardened.



We typically use 8620 for case hardened parts.

--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

http://www.machines-cnc.net:81/

"Martin Whybrow" wrote in message
news
Further to my last post (Material for clamping wedges), I've now
determined
that the original parts were case hardened steel.
I will be making the parts up soon, but I don't know what grades of steel
can be case hardened; the commonly listed steels for case hardening are
EN3B
(SAE 1017 or 1022) and EN32 (SAE1016), but these are not readily available
in small quantities (600mm / 2'). I can obtain EN1A (free machining mild
steel, no direct SAE equivalent) or EN8B (closest equivalents are SAE1040
and SAE1038) from model-engineer-friendly suppliers, but I am unsure if
these can be case hardened. I plan on using Kasenit case hardening powder
to
harden these parts. Can anyone enlighten me?
Martin.

Sticking to ordinary grades of low-carbon steel, I have yet to find one that
wouldn't take a decent case using Kasenit, and I've been using it for about
40 years.

I haven't *intentionally* tried to harden medium-carbon steels, such as
1040, but I'll bet it would be reasonably satisfactory. I've probably done
it without knowing what grade I was working with.

What are you trying to achieve? A very thin case, or a thicker one? Thin
cases are much easier and put less stress on the steel. So you don't have to
bother about tempering them.

--
Ed Huntress

"Ed Huntress" wrote in message
...
"Martin Whybrow" wrote in message
news
Further to my last post (Material for clamping wedges), I've now
determined
that the original parts were case hardened steel.
I will be making the parts up soon, but I don't know what grades of
steel
can be case hardened; the commonly listed steels for case hardening are
EN3B
(SAE 1017 or 1022) and EN32 (SAE1016), but these are not readily
available
in small quantities (600mm / 2'). I can obtain EN1A (free machining mild
steel, no direct SAE equivalent) or EN8B (closest equivalents are
SAE1040
and SAE1038) from model-engineer-friendly suppliers, but I am unsure if
these can be case hardened. I plan on using Kasenit case hardening
powder
to
harden these parts. Can anyone enlighten me?
Martin.

Sticking to ordinary grades of low-carbon steel, I have yet to find one
that
wouldn't take a decent case using Kasenit, and I've been using it for
about
40 years.

I haven't *intentionally* tried to harden medium-carbon steels, such as
1040, but I'll bet it would be reasonably satisfactory. I've probably done
it without knowing what grade I was working with.

What are you trying to achieve? A very thin case, or a thicker one? Thin
cases are much easier and put less stress on the steel. So you don't have
to
bother about tempering them.

--
Ed Huntress

Thanks for all the replies.
It hadn't occurred to me that the reason low carbon steels are used for case
hardened applications is that the core metal will remain in a soft state and
therefore add strength to the part; it's obvious now I think about it.
The application is for a clamping wedge for my milling machine's swivel;
it's a 3/4" rod, narrowed to a 3/8" flat section at one end with an 18.5
degree taper on the lower narrow face. The tapered section passes through a
slot in the table clamp (imagine a T bolt with a rectangular slot through
the shank), the lower edge of this hole has a matching wedge on the lower
face so that as the rod is driven through it, it clamps the swivel onto the
saddle. The clamps appear to be cast and are relatively soft; the clamping
wedge is hardened to prevent it galling against the opposing wedge surface
in the clamp and therefore probably only requires a thin layer of case
hardening.
Martin

--
martindot herewhybrowat herentlworlddot herecom

"Martin Whybrow" wrote in message
...

Thanks for all the replies.
It hadn't occurred to me that the reason low carbon steels are used for
case
hardened applications is that the core metal will remain in a soft state
and
therefore add strength to the part; it's obvious now I think about it.

Be a bit wary of this idea, which is the shorthand way it's often explained
at this level. In fact, a properly hardened piece of higher-carbon steel is
quite a lot stronger, and even "tougher."

It depends on how you define "tough." The through-hardened steel, if not
excessively hard and if properly tempered, will have far more impact
strength than the mild steel with a case. The impact strength is based on
how much impact it takes to break the part.

The thing is, the mild steel will reach its yield point at a much lower
impact, simply because it has little yield strength. Then the energy of the
impact will be absorbed in bending the steel.

It's very difficult to measure this but the fact is the mild steel actually
will *break* with less impact energy than will the properly hardened steel,
as well. But try to get that impact energy delivered to the mild steel
without bending it so that it absorbs the energy in bending. It isn't easy,
and it leads to the practical conclusion that the mild steel is "tougher"
than the hardened steel. In a common, everyday sense, it is. But not in a
strict sense.

Anyway, just be aware that the supposed "toughness" of case-hardened mild
steel refers to the fact that it isn't likely to break on impact. But it
will bend or otherwise deform permanently, at much lower impact levels than
the hardened steel will.

The application is for a clamping wedge for my milling machine's swivel;
it's a 3/4" rod, narrowed to a 3/8" flat section at one end with an 18.5
degree taper on the lower narrow face. The tapered section passes through
a
slot in the table clamp (imagine a T bolt with a rectangular slot through
the shank), the lower edge of this hole has a matching wedge on the lower
face so that as the rod is driven through it, it clamps the swivel onto
the
saddle. The clamps appear to be cast and are relatively soft; the clamping
wedge is hardened to prevent it galling against the opposing wedge surface
in the clamp and therefore probably only requires a thin layer of case
hardening.
Martin

Yes, that sounds like a thin-case job. I wouldn't get overwrought about
which grade of steel you choose. Try to get a plain-carbon steel that is in
the low-carbon range. Some alloying ingredients can make it difficult to
case-harden, but I forget which ones.

--
Ed Huntress

Anthony wrote:

"bw" wrote in
:




Any mild steel can be case hardened.



We typically use 8620 for case hardened parts.

I'm going to agree.

8620 is very easy to machine and any heat treater can handle it. The
result is boringly predictable. As I recall, a typical surface
hardness is in the 45 to 50 Rc range. The surface is very durable,
often used for wear surfaces of Gears, shafts and seal faces.

My experience with Kasenit is that the result may be unpredictable. I
once had a part shatter because the case was too deep. I'm sure that
has a lot to do with my clumsy and inexperienced methods. But given
the alternative of 8620, I don't see any reason to spend the time and
expense of honing my heat treating skills.

If you need small quantities, try eBay:

http://makeashorterlink.com/?N5F922F4B

George.