Jon Weaver wrote:

I want to harden a piece of steel, and from my school metal work days,
I think that I can simply heat it to red hot and then plung it into
'oil'

Is this the right? If so, what sort of oil should I use.. Are we
talking normal engine oil, or there there a special kind??

As you can tell, I havn't really got a clue what I am talking about,
so any info would be appreciated

Jon

There is a special recommended oil and the temperature of the oil is of
importance too. IF the oil is too cold you may get stress cracks. Also
there is a rule that you should have a certain volume of oil for each
pound of metal you quench or the oil temp will go too high. Keep the
piece suspended in the oil rather than throwing it in a tank so there is
even cooling around the whole piece.

Some others probably have more exact numbers for you. I usually use air
hardning stuff because I hate the smoke.

John

Jon sez: "I want to harden a piece of steel, and from my school metal work
days,
I think that I can simply heat it to red hot and then plunge it into 'oil'."

It would appear from your question that you are using hardening and
tempering as interchangeable terms. They are not. Hardening is one
process, tempering is a different process. You can't harden just any piece
of steel. It has to have a certain minimum amount of carbon to be
hardenable. Select steel that is guaranteed heat-treatable.

Heat treating is a 2 part process. First the steel is heated and quenched -
this hardens it. However it is usually too hard and has internal stresses
from the quench. Next, the hardened steel is "tempered" which is the 2nd
process. Tempering relaxes internal stresses caused by rapid cooling of the
quench and softens the piece somewhat to the desired degree of hardness.

Select a tool steel such as O-1, (oil hardening) or W-1, (water hardening).
Oftentimes heat treating instructions are included with the steel or are in
the catalog it is selected from. Drill rod is also tool steel. Remember
there are 2 steps to heat treating steel; hardening *and* tempering.

I have had very good results (thanx to Ed Huntress and a book called "Tool
Steel Simplified") with the following:

1. Heat O-1 to red or "beyond magnetic" and quench in motor oil.

2. Then while the piece is still too hot to handle with bare hands place it
in a 375 deg. oven for 45 minutes.

I have successfully made taps and a few dies from O-1 drill rod with this
procedure.

Bob Swinney






"Jon Weaver" wrote in message
om...jon sez:
Is this the right? If so, what sort of oil should I use.. Are we
talking normal engine oil, or there there a special kind??

As you can tell, I havn't really got a clue what I am talking about,
so any info would be appreciated

Jon

On 3 Aug 2003 13:46:32 -0700, (Jon Weaver) wrote:
I want to harden a piece of steel, and from my school metal work days,
I think that I can simply heat it to red hot and then plung it into
'oil'

Is this the right? If so, what sort of oil should I use.. Are we
talking normal engine oil, or there there a special kind??

As you can tell, I havn't really got a clue what I am talking about,
so any info would be appreciated

There's a bit more involved. First you have to know the type
of steel. Some steels can be heat treated, others can't. Basically
this is a matter of the carbon content of the steel. Below about
20 points, you have mild steel, which won't harden. Above about
90 points carbon, hardening becomes tricky (big risk of cracking
if you don't do it exactly right). Other alloying elements can also
change the heat treating process.

Each kind of steel requires heating to a certain temperature, then
quenching in a certain medium (sometimes water, sometimes oil,
sometimes just cooling in air, depending on the particular requirements
of the particular steel). Then it needs to be tempered because
hardening makes the steel brittle, and the "temper" of the metal has
to be drawn back a bit to restore some toughness. (Tempering is
usually done between 400 and 600 degrees, depending on the
particular steel, and the final properties you want.)

So with an unknown steel alloy, you're shooting in the dark.
If you know the alloy, then you have a better chance of being
able to harden it successfully. For example, suppose your
steel was O1. Then you'd heat it to cherry red (just above
the temperature where a magnet won't stick to it), then plunge
it in oil (vegetable or mineral oil preferred, though petroleum oil
can be used). Then reheat to about 475 degrees to temper
it.

OTOH, if the steel is W1, you'd have to heat it a bit hotter,
quench it in *water*, and draw the temper at about 575
degrees. If it were A1, then you'd have to let it air cool.
Quenching in either water or oil would cause it to crack.

Gary

Jon, if you want to "harden" a piece of steel because it lost its temper
from overgrinding and will no longer retain its sharpness, then the
process is more complicated than you think. You have to first anneal,
then harden, and lastly temper. Let me know, if you want more detail. I
delayed answering your question because I'm sure I"m one of the least
expert people on this group.


In article ,
says...
Jon Weaver wrote:

I want to harden a piece of steel, and from my school metal work days,
I think that I can simply heat it to red hot and then plung it into
'oil'

Is this the right? If so, what sort of oil should I use.. Are we
talking normal engine oil, or there there a special kind??

As you can tell, I havn't really got a clue what I am talking about,
so any info would be appreciated

Jon

Gary Coffman wrote in message . ..
On 3 Aug 2003 13:46:32 -0700, (Jon Weaver) wrote:
I want to harden a piece of steel, and from my school metal work days,
I think that I can simply heat it to red hot and then plung it into
'oil'

Is this the right? If so, what sort of oil should I use.. Are we
talking normal engine oil, or there there a special kind??

As you can tell, I havn't really got a clue what I am talking about,
so any info would be appreciated

There's a bit more involved. First you have to know the type
of steel. Some steels can be heat treated, others can't. Basically
this is a matter of the carbon content of the steel. Below about
20 points, you have mild steel, which won't harden. Above about
90 points carbon, hardening becomes tricky (big risk of cracking
if you don't do it exactly right). Other alloying elements can also
change the heat treating process.

Each kind of steel requires heating to a certain temperature, then
quenching in a certain medium (sometimes water, sometimes oil,
sometimes just cooling in air, depending on the particular requirements
of the particular steel). Then it needs to be tempered because
hardening makes the steel brittle, and the "temper" of the metal has
to be drawn back a bit to restore some toughness. (Tempering is
usually done between 400 and 600 degrees, depending on the
particular steel, and the final properties you want.)

So with an unknown steel alloy, you're shooting in the dark.
If you know the alloy, then you have a better chance of being
able to harden it successfully. For example, suppose your
steel was O1. Then you'd heat it to cherry red (just above
the temperature where a magnet won't stick to it), then plunge
it in oil (vegetable or mineral oil preferred, though petroleum oil
can be used). Then reheat to about 475 degrees to temper
it.

OTOH, if the steel is W1, you'd have to heat it a bit hotter,
quench it in *water*, and draw the temper at about 575
degrees. If it were A1, then you'd have to let it air cool.
Quenching in either water or oil would cause it to crack.

Gary

Good advice, BTW mineral oil is a petroleum oil. I prefer to use used
motor oil, and I recommend that it be pre-heated to about 100 degrees
F, it will have less tendency to stress crack. Keep a CO2 fire
extinguisher handy just in case. If you use veggie oil, avoid the
unsaturated ones such as safflower, canola, corn or soybean, they will
form a varnish on the steel, use cottonseed, coconut, or peanut oil.
Better yet, see if you can get old deepfryer oil from a local
restaurant, they normally change it once a week.-Jitney

On Sun, 03 Aug 2003 22:16:59 -0400, Gary Coffman
wrote:

snip
OTOH, if the steel is W1, you'd have to heat it a bit hotter,
quench it in *water*, and draw the temper at about 575
degrees. If it were A1, then you'd have to let it air cool.
Quenching in either water or oil would cause it to crack.


W-1 is quenched in brine, not water. The brine can be made by
dissolving as much salt as the amount of water you are using will
take.

For oil quenching smaller/thinner pieces of steel I have thinned
regular (non-detergent usually) motor oils with kerosene (up to maybe
33 to 50 percent kero) in order to get more immediate contact and
better convection when the part is plunged in the oil.

There is some risk of a flame or flare up with quenching oils, work
safely.



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----

Jon Weaver wrote:

It seems that there is much more to this than I thought, but what you
describe is EXACTLY what I am trying to do.

I often 'grind' a tool, but once its ground, its lost its 'hardness'.
I wondered if there was a simple process to restore its 'harness' a
little.

In light of the complexity of this process, I probably won't bother..
But, if its not too much trouble, I would be very interested in
hearing about what is involved!

All the best

Jon

You might want to look for one of the slow turning, wet wheel type,
sharpening grinders. That would seem the easyest anwer to overheating
your cutting tools when sharpning.

Cheers
Trevor Jones

(Jon Weaver) wrote in message . com...
I want to harden a piece of steel, and from my school metal work days,
I think that I can simply heat it to red hot and then plung it into
'oil'

Is this the right? If so, what sort of oil should I use.. Are we
talking normal engine oil, or there there a special kind??

As you can tell, I havn't really got a clue what I am talking about,
so any info would be appreciated

Jon

There are special quenching oils available, they have higher
flashpoints than something like motor oil would. Any URLs I've got
are for U.S. suppliers, not U.K., sorry. If it's just the one piece,
use motor oil. As others have posted, methodology depends a lot on
the type of steel it is. If it's mystery metal, it's a crap shoot and
mild steel won't harden that way, you'd have to caseharden it with
Kasenit powder or the equivalent. If you buy known alloys for your
parts, the steel should come with a chart of how to heat-treat it or
it should be available from the catalog you ordered it from. You can
harden high carbon steel by heating it red to the non-magnetic point,
quenching it, and then tempering by color, but most alloy steels
won't develop anything like their full potential by doing things that
way, you need to follow the directions. It sometimes takes a soak at
elevated temperatures followed by a quench and then a prolonged(hours)
tempering at a much lower temperature with no quench, just
air-cooling. I've made taps and dies out of O1 both ways, if you
follow the directions included with the steel, things work out a whole
lot better. The change in the steel's crystal structures doesn't take
place instantaneously, this why the heat treating businesses get the
big bucks for doing the job, they know the times and temps needed and
have the equipment.

Stan

A google of the web will show a large number of hardening and tempering of
steel webpages.

--
Bob May
Losing weight is easy! If you ever want to lose weight, eat and drink less.
Works evevery time it is tried!

"Jack Erbes" wrote in message
...
W-1 is quenched in brine, not water. The brine can be made by
dissolving as much salt as the amount of water you are using will
take.

...And then cutting it 1:1 with straight water.

Tim

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms

Jon Weaver wrote:

I want to harden a piece of steel, and from my school metal work days,
I think that I can simply heat it to red hot and then plung it into
'oil'

Is this the right? If so, what sort of oil should I use.. Are we
talking normal engine oil, or there there a special kind??

As you can tell, I havn't really got a clue what I am talking about,
so any info would be appreciated

Jon


http://www.mcmaster.com/catalog/109/html/1975.html#.
Item 3202K5

Be sure to plunge the part quickly and completely below the surface and
agitate it to avoid a vapor blanket from forming.

On Mon, 4 Aug 2003 16:01:19 -0500, "Tim Williams"
wrote:

"Jack Erbes" wrote in message
.. .
W-1 is quenched in brine, not water. The brine can be made by
dissolving as much salt as the amount of water you are using will
take.

..And then cutting it 1:1 with straight water.


I just checked the Brownells catalog. I was wrong about the brine
being saturated. It was a 8 percent solution and made with 3/4 lb. of
rock salt and 1 gallon of water. I remember I scaled it down and made
a pint of brine and it lasted me for several years. I only made small
parts and only occasionally.

It worked good though. I learned the hard way not to test a firing
pin until after I tempered it. I let the hammer fall on an empty
chamber while fitting a pin in a single shot rifle and when the firing
pin body stopped the tip kept on going.

I like the caution in the Brownells catalog in the tempering
instructions, it says you can use a conventional oven for some
tempering but "DO NOT USE A MICROWAVE!".



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----

I've had good luck with transmission fluid on oil hardening steels.
Greg Sefton

Would S7 be considered oil hardening?

--
Steve Worcester
www.turningwood.com
Better Woodturning through Technology
(And a hell of alotta practice)



"Bray Haven" wrote in message
...
I've had good luck with transmission fluid on oil hardening steels.
Greg Sefton

Bray Haven wrote:

I've had good luck with transmission fluid on oil hardening steels.
Greg Sefton


Automatic or manual?

On Mon, 04 Aug 2003 07:53:49 -0400, Jack Erbes
wrote:
On Sun, 03 Aug 2003 22:16:59 -0400, Gary Coffman
wrote:

snip
OTOH, if the steel is W1, you'd have to heat it a bit hotter,
quench it in *water*, and draw the temper at about 575
degrees. If it were A1, then you'd have to let it air cool.
Quenching in either water or oil would cause it to crack.


W-1 is quenched in brine, not water. The brine can be made by
dissolving as much salt as the amount of water you are using will
take.

You could do that. There are a lot of old nostrums for use as
quenching solutions. But plain cool water (with perhaps a few
drops of a good wetting agent) works just fine.

Gary

"Gary R Coffman" wrote in message
...
On Mon, 04 Aug 2003 07:53:49 -0400, Jack Erbes
wrote:
On Sun, 03 Aug 2003 22:16:59 -0400, Gary Coffman
wrote:

snip
OTOH, if the steel is W1, you'd have to heat it a bit hotter,
quench it in *water*, and draw the temper at about 575
degrees. If it were A1, then you'd have to let it air cool.
Quenching in either water or oil would cause it to crack.


W-1 is quenched in brine, not water. The brine can be made by
dissolving as much salt as the amount of water you are using will
take.

You could do that. There are a lot of old nostrums for use as
quenching solutions. But plain cool water (with perhaps a few
drops of a good wetting agent) works just fine.

Gary


The idea behind using brine is that it is less inclined to leave attached
bubbles on the surface of the steel as the water boils, which leave soft
spots on the steel. It's a well-established and scientific method, and not
one of the "old nostrums". The old nostrums are such things as quenching in
the blood of a Vestal virgin. It drove the price of steel up into the
stratosphere. g

I didn't read this thread, but the tempering temperature for W1 should be
well below 575 for most purposes. Most water-hardening steels give the best
combination of toughness and hardness when tempered at around 375 deg. F for
three or four hours, or more.

However, if this is for some purpose that requires ductility as well as
toughness, forget what I said.

Ed Huntress