I have some smallish (1.20" dia x .25" thick) that I want to heat
treat.

Some are A2 and the rest hot rolled.

I intend to case harden the HRS ones because a hard 'skin' is all I
really need.

So my question is, can I also 'case' the A2 ones, so as not to bother
my friend who has a nice heat treat oven? Or will they warp?

TIA

Lewis

*****

On 12/31/2010 08:28 AM, wrote:
I have some smallish (1.20" dia x .25" thick) that I want to heat
treat.

Some are A2 and the rest hot rolled.

I intend to case harden the HRS ones because a hard 'skin' is all I
really need.

So my question is, can I also 'case' the A2 ones, so as not to bother
my friend who has a nice heat treat oven? Or will they warp?

I don't know, but I'll bet that the real answer is either "it depends"
or "it won't make any difference". If you're case hardening by putting
them into a carburizing atmosphere and heating them for a good long
time, then my limited knowledge suggests that no, it won't make a
difference. If you're treating them with nitrogen or something, then I
dunno.

The bigger question for me would be -- can you _quench_ them and _draw_
them the same as the plain steel ones. I very much suspect the answer
to that is "hell no".

What happens when you dump a 1/4" thick piece of A2 into water or oil?

If I were you and I knew which was which, I'd keep them separate and do
two batches. If I _didn't_ know which was which any more, I'd treat all
of them like A2 once, save out the ones that actually harden, then case
harden whatever was still soft after the first step.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

On 12/31/2010 10:41 AM, John R. Carroll wrote:
Tim Wescott wrote:

What happens when you dump a 1/4" thick piece of A2 into water or oil?

A2 is an air hardening tool steel.
You don't need to dump it in anything.

Yes, I know that. If you read the OP's question he wants to mix a bunch
of parts that are made from A2 with a bunch of parts that are made from
mild steel, then run them all through some case hardening process as if
they were all mild steel.

I've never hardened A2 the right way, much less chucked a red-hot piece
of it into water, so I don't know what will happen. But that's what
_he_ wants to do, and I'm questioning whether the steel will say "oh,
that's all right then", or if it will say "CRACK!!!".

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

John R. Carroll wrote:
Tim Wescott wrote:
On 12/31/2010 10:41 AM, John R. Carroll wrote:
Tim Wescott wrote:

What happens when you dump a 1/4" thick piece of A2 into water or
oil?

A2 is an air hardening tool steel.
You don't need to dump it in anything.

Yes, I know that. If you read the OP's question he wants to mix a
bunch of parts that are made from A2 with a bunch of parts that are
made from mild steel, then run them all through some case hardening
process as if they were all mild steel.

I've never hardened A2 the right way, much less chucked a red-hot
piece of it into water, so I don't know what will happen. But that's
what _he_ wants to do, and I'm questioning whether the steel will say
"oh, that's all right then", or if it will say "CRACK!!!".

The latter, I suspect.
LOL
What he could do is take his low carbon steel and put it in SS foil bags
with a carbeurizing source.
Then, put that and his A2 in a furnace and run it up to 1875 degrees F and
hold it for a while.
When everything was nice and toasty, he could shut off the furnace, remove
the mild steel and dump it out of the slit open bags into a can of motor
oil.
When that was done, the A2 could be removed from the furnace and set on a
fire brick to cool to room temp.

The mild steel will have a shallow case and the A2 will be about 58 RC.


To caseharden the low carbon steel, get some Kasenit and follow the
directions on the can. Either you cover the part with the powder and
heat to 1800 deg. and hold it there for about a half hour or you can
heat up the part and immerse it in the powder.
Basicly it is the ferrous cynaide or pressate of soda ( they put it in
salt to make it flow easier) that adds the carbon to the metal. For
the heattreating of the A2, heat it up until a magnet will not adhere to
it and then air cool it under a fan. The low carbon steel piece will
have to be heated and quenched in water to get the full hardness.


John