Heattreating a large batch

Sando

Sando

Knife Maker
Joined
Jul 4, 2002
Messages
1,148
I'm gonna be treating a batch of blades today (ats-34).

I have them 2 per foil packet. 3 packets.

I plan on putting them all in at the proper temp, raise the temp, soak. Now the question. After I pull out the first packet, how long should I leave the second packet in there to get back to temp? Do I let the oven return to temp and re-soak?

???

Steve
 
Steve, I believe you are over shooting the capabilty of your equipment. So long as I am able to quench only one blade at a time (packet in this case) I would heat treat one blade at a time. In addition, packing two blades to the packet throws other problems into the mix. The soak time will change because the effective cross section changes and there is that nasty little warp problem too when handling more than one blade at a time. Also, when stacked like that the inner blade sides will not quench consistantly with the outer sides. This also helps to entice warpage not to mention hardening inconsistancy. My advise is one blade at a time, especially with the limitations of our equipment. Shoot for precision instead of time saving quantity. Go for uninterrupted and timely cycles per blade.

Other than that I am tickled you have the HT bug. You are going to do very well.

RL
 
yeaup what Roger said.

I'll do three at a time it's the most
I feel I can get out of the oven fast enough to
quench properly.
wrap each one by it self
and leave space between them in the oven for an even heat.:D Pun intended.:D
 
Thanks guys, I almost took your advice <grin>.

I did 2 packets of 2 - instead of three. Everything went fine - at least with the heat and quench.

However, one blade warped a little. I wanted to straighten it while it was still warm, but it's cold outside. So I went to warm it up - just a bit - before straightening, by placing it back in the over - for just a bit! (OK everyone does something stupid once in a while). Well too long it seems. I straightened it, but it lost it's hardness. Dang, Dang, Dang.

I think I can do it over tho. Can't I?

3 blades tested at around 61 before Cryo - textbook. The 'straightened' blade is around 45 - ouch. Dang, Dang, Dang.

I put them all in nitro - we'll see in the morning.

Steve

PS, RLinger. the blades were under 3/32" thick.
 
Steve, slow down pal. You may be better served by seeing an investment banker. When you get your production knife factory going I hope you'll accept my job application form.

Sounds like you might have a Rockwell tester. Do you:cool: :cool: :cool: ?

RL
 
RE: Hiring. Well Roger I'll promise, if you promise to hire the fool if you get there first! ;) ;)

They are 4 steak knives. Very thin. Warping was expected. Because of my circumstances it would take me several days to do all 4 blades. I have to takes risks. <sigh> It's a bummer when you risk and it works and then you screwup something else.

I have an ames harness tester. Not real accurate, but it'll find a soft blade that's for sure! (Now that I remember, it reads a bit low, based on some Paul Bos blades I have.) So actually they are probably over 61.

So, can I re-harden this blade?

Steve
 
Roger,

On the FWIW, side. You might find this quench method interesting:


I don't remove them from the foil.
I place them between 2 1"x8"x12" aluminum blocks.
Place about 10lbs of weight on top
Then I use the compressor to blow air around them thru the gap.

The blade comes out with really cool, swirling color patterns - they are not exposed to air until cool. The color patterns, I believe, are from the smoke in the packet. But without getting hit with oxygen ever, there isn't much discoloration.

It's an idea I picked up here on the forums. Seems OK by me.

Steve
 
Steve, I ain't going to BS ya. I don't really know. I've never tried it before with the supers. I think you bit the big one if I had to guess. Put it back in foil, run it up and quench it. It's not like you don't have a Rockwell tester. Equalize it first on the way up. Do that around 1400 F. for a little less than 10 min..

Get on Ebay and start looking for a test block or two so you can calibrate your tester. Try to get one as close to our hardness likings as available. They seem scarce at the hardnesses we want though; at least at a price we can match.

One blade at a time Steve.

RL
 
Steve, I was writting a responce when you entered your post about the aluminum quench blocks.

Steve, I am convinced they are not needed. I have another reason and it is more of a mental block than anything else: How can I get two blocks perfectly flat against two beveled sides so as to equally quench the narrow edges of the blade (?). Steve, I track vendor air quench data sheets with air quench. I see no reason for it and in addition if you hang the blade in the wind tunnel chances of blade warpage is minimized. I thought about using quench plates for a long time until I figured out I don't think I can get a consistant quench.
Probably just me. I'm stubborn like that.

RL
 
Steve you can heat treat it again
when you straighten blades do it on the first cooling.

On the 154cm (same heat treat)
it has to get quite cool to get it's magnetism back
it seems to be a lot cooler than O1 for this to happen..
 
Originally posted by rlinger
How can I get two blocks perfectly flat against two beveled sides so as to equally quench
Click to expand...

I have the same fears, Roger. How can we be sure that the beveled sections of the balde is quenched? Perhaps by sucking the heat rapidliy from the thicker sections of the blade the thinner, beveled sections follow and are quenched well enough? Trouble is, a lot of makers do it this way, and their blades are fine. I've actually been thinking of maybe a pair of 1" thick slabs of aluminum attached to the jaws of a woodworkers vise. Peter Atwood just uses the vise, as does Howard Hitchmough. I was thinking of constructing something along the same lines, and maybe over-engineering it (as is my nature) to include an air cylinder to compress the blade in its foil in a quick manner.
 
just a thought
if using a vise just put the spine
and tang in and move air on the edge
it's only the edge you're most concerned with for hardening anyway
the rest is for keeping it straight..

I put mine on my Magnetic chuck on my grinder
:)
 
Your fears over heat transfer from the bevels into the AL plates are unfounded. The plates suck the heat out of the steel far faster than an air quench-even a forced air quench. I've done it both ways, and, I'll take a press quench over anything.
 
Other than my screwup after the quench, I'm not worried about multiblades, or quench blocks, or leaving them in the packet.

Besides look how cool the blade looks - zero scale and neat colors:

blade.jpg


Roger and Graymaker, I did listen. I'm not going to quench one packet and leave one in the oven. I'm going to do them at once. The blades are all very consistent in RC and hard. Works just fine for me.

However, if I have 25% warp consistently, I'll have to change something.

And thanks, Graymaker, I'll try a re-heat before tossing it out.

Steve
 
The thick aluminum plates are the way to go. And people wonder why I grind after heat treat, I never have a blade warp:)
The aluminum will pull the heat out much faster than a magnetic chuck.
FWIW, the guys at Crucible convinced me of the need for them back when I was working 3V and have been using them ever since.
I do up to 3 packs with 2 blades in each (same thicknesses)and get consistent Rc.
 
I need to back up
I cool with the compressed air in a can
and then put them on the Chuck to help keep them straight
then straighten if needed. I think I'll try out the Plates.
Rene's been doing it this way for some time now..

kit do you un pack them first? if so I assume you put them
in your pack end for end or side by side and not flats to flats.
:confused:
 
Well yes, Dan, you were right. Inside the packet, they are stacked - one atop another. Then when I quenched, the two packets were side by side.

I suppose I should make them all side by side - I can still do 4 blades.

Steve
 
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