Hi everyone,

Can anyone please tell me what machinable pre-hard steel has the
highest compressive yield strength ? I'm guessing it would be a pre-
hard 4000 series, perhaps 4340 or a bearing steel or pre-hard tool
steel.

I'm looking for the highest yield strength I can find in a steel that
is still machinable, i.e., not so hard that it can't really be
machined effectively. Depending on how the part is machined, I would
need a thickness of around 1.338" or 1.585".

Thanks
John

John2005 wrote:
Hi everyone,

Can anyone please tell me what machinable pre-hard steel has the
highest compressive yield strength ? I'm guessing it would be a pre-
hard 4000 series, perhaps 4340 or a bearing steel or pre-hard tool
steel.

I'm looking for the highest yield strength I can find in a steel that
is still machinable, i.e., not so hard that it can't really be
machined effectively. Depending on how the part is machined, I would
need a thickness of around 1.338" or 1.585".



NAK 55


--

John R. Carroll
www.machiningsolution.com

Black Dragon wrote:
John R. Carroll wrote:

John2005 wrote:
Hi everyone,

Can anyone please tell me what machinable pre-hard steel has the
highest compressive yield strength ? I'm guessing it would be a pre-
hard 4000 series, perhaps 4340 or a bearing steel or pre-hard tool
steel.

I'm looking for the highest yield strength I can find in a steel
that is still machinable, i.e., not so hard that it can't really be
machined effectively. Depending on how the part is machined, I would
need a thickness of around 1.338" or 1.585".

NAK 55

DH2F

Viscount 44

44 is a pain. It's nothng more than H-13 without the Tungsten.
It also isn't pre hardened. You have to do that yourself.

--

John R. Carroll
www.machiningsolution.com

Thanks for the feedback guys,

After reading your replies, I searched online for NAK55 and DH2F. I
will also check into the Viscount.

I read something about one of the grades in a "hi hard" condition of
45/48 RC, which would probably have a high compressive yield strength
in that hardness. At about what point in general would a pre-hard
steel be too hard to really machine effectively ?

Can you recommend any online sources or books that have compressive
yield strengths for these materials in their pre-hard state ? So far,
I have not found much. Can you recommend any sources of supply for
small prototype quantities ?

Thanks again guys,
John

Black Dragon wrote:
John R. Carroll wrote:

Black Dragon wrote:
John R. Carroll wrote:

John2005 wrote:
Hi everyone,


John, Viscount (pronounced vi-count) 44 is Rockwell C 42/46 off the
shelf. The only heat treatment I've ever seen done to it is nitriding
for wear resistance. It's more difficult to drill than NAK 55 and DH2F
but other than that it's not a bad material to work with.

I built seat belt cover molds out of it in the 70's for Allied Chemical.
They tried to save a buck by having me requote the tools in Viscount instead
of the S-7 I'd originally wanted to use.
When that little window shut off in the center where the little latch
release mechanism ( the thingy with GM on it ) would start to flash a lot
they had to be welded. Guess what happened to those little cavities when we
put enough heat into them to get a good weld?
LOL
We converted a lot of cavities in the end to S-7 so I guess you're right.
It's not bad material at all EG


--

John R. Carroll
www.machiningsolution.com

John2005 wrote:
Thanks for the feedback guys,

After reading your replies, I searched online for NAK55 and DH2F. I
will also check into the Viscount.

I read something about one of the grades in a "hi hard" condition of
45/48 RC, which would probably have a high compressive yield strength
in that hardness.

NAK has a grade this hard but you might also be refering to something known
as Super P-20.
Thyssen makes it.

At about what point in general would a pre-hard
steel be too hard to really machine effectively ?

Tooling for hard milling has come a long way over the years.
People are machining 60 RC D-2 these days from the start.


--

John R. Carroll
www.machiningsolution.com

On Sat, 31 May 2008 14:52:44 -0700 (PDT), John2005
wrote:
snip
I'm looking for the highest yield strength I can find in a steel that
is still machinable, i.e., not so hard that it can't really be
machined effectively.
snip
==========
Depending on how many you have to do, consider EDM. Hardness is
no problem.

FWIW -- iron is a minority ingredient in some of the "super
steels," and while ther performance is "out of this world," so is
the price.

for some additional info click on
http://www.brownmac.com/pdf/BrownMcFarlaneHSSSP.pdf
http://en.wikipedia.org/wiki/Maraging_steel
http://www.matweb.com/search/GetMatl...=Latrobe+Steel
http://www.thomasnet.com/northern-ne...9790408-1.html
http://www.allvac.com/allvac/pages/P.../vascomaxt.pdf






Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).

Black Dragon wrote:
John R. Carroll wrote:

Black Dragon wrote:
John R. Carroll wrote:

Black Dragon wrote:
John R. Carroll wrote:

John2005 wrote:
Hi everyone,


Yep. Viscount 44 is a terrible steel alright.

Well, we hated the stuff but to each his own.

I'd much rather machine
DH2F, it's a wee bit more forgiving. g

What is that anyway?
D-2?

--

John R. Carroll
www.machiningsolution.com

Tooling for hard milling has come a long way over the years.
People are machining 60 RC D-2 these days from the start.

Tool steel at RC 60 would be plenty strong. What type of cutter and
feed rates are needed to machine tool steel this hard ? I didn't think
anything would really cut tool steel that hard, let alone do it cost
effectively. EDM may be a way to go as well, but I'm not sure
expensive it is for two prototype pieces to test.

I think most tool steel at around 52-55 RC would have a yield around
300,000 PSI which would be plenty strong (280,000 PSI compressive
yield strength would be enough for me) . A2 or S7 would probably be
ideal, but I don't know if their available in pre-hard, or at these
hardness levels. Generally I had thought that anything at these
hardness levels pretty much had to be ground.

I've drilled and countersunk pre-hard 4140 (I think it was 27-32 RC).
I just used a new HSS bit and I was surprised how easy it cut but I
had always thought machining tool steel in the 55-60 RC range was out
of the question.

John

John2005 wrote:
Tooling for hard milling has come a long way over the years.
People are machining 60 RC D-2 these days from the start.

Tool steel at RC 60 would be plenty strong. What type of cutter and
feed rates are needed to machine tool steel this hard ? I didn't think
anything would really cut tool steel that hard, let alone do it cost
effectively. EDM may be a way to go as well, but I'm not sure
expensive it is for two prototype pieces to test.

I think most tool steel at around 52-55 RC would have a yield around
300,000 PSI which would be plenty strong (280,000 PSI compressive
yield strength would be enough for me) . A2 or S7 would probably be
ideal, but I don't know if their available in pre-hard, or at these
hardness levels. Generally I had thought that anything at these
hardness levels pretty much had to be ground.

I've drilled and countersunk pre-hard 4140 (I think it was 27-32 RC).
I just used a new HSS bit and I was surprised how easy it cut but I
had always thought machining tool steel in the 55-60 RC range was out
of the question.


http://www.moldmakingtechnology.com/...on/greenleaf1/

MMT inMotion Multimedia Presentation

The Benefits & Techniques Of Hard Milling With Ceramics

--

John R. Carroll
www.machiningsolution.com

Thanks for the additional feedback and links guys, I will check into
this a little further.

The shop I'm having machine the parts has no in house heat treating. I
was trying to avoid having to fool with machining a few thousandths
over size, heat treating, and griding to final size. From an accuracy
standpoint, it's also best to machine this in one setup.

I might be able to get close to what I need or perhaps I will have to
heat treat and grind. Perhaps I will test some pre-hard and see how it
does first. I will also check out the links John gave regarding hard
milling, that sounds interesting.

Thanks again and take care guys,
John