Heattreating a large batch

FWIW, I have found that using the aluminum plates sucks the heat out even faster than just the plain old steel woodworkers vise. It makes sense since aluminum is a great conductor. And yes, you can leave the blades in the packet.
 
Do as you wish but I would not stack unless I had experience enough to know how to tweak the soak times. Quench plates: I'll never disagree with Kit on this but you have to remember Kit doesn't bevel his work before quenching. If I had a flat piece of steel I'd want to slap a couple quench plates on it too. I'd like to figure out a way to make the plates hug the blade bevels. As I stated before, most of it is just a mental block with me and perhaps I should just go ahead and try it.

I ain't buying into this stacking blades deal though. I don't know enough yet to speak any more than this: I believe the story is in the beautiful colors at the thinner parts of that blade you posted.

RL
 
Roger,
Think of it this way. If you quench a 1/4" blade in the alu plates, isn't that about the same as quenching two 1/8" blades stacked together? :)
Again, mine are not ground yet.
I've tested and tested and never seen a difference in Rc or performance with one blade or two in the alu plates.
You just gotta be like the Roadrunner (beep, beep) getting them out of the oven and on the plates and pressed.
:)
 
Kit, just to make sure I see your picture correctly enough - are you quenching the two blades as they are stacked together or quenching seperately. I understand that you are stacking them during autenitization but are you making a double decker sandwich, so to speak, during quench with the plates ? I can't believe you of all of us would do that, beveled or not.

The way you grind is the solution to me for using quench plates. Your steel is flat or relatively so. In this case I have no reason not to promote the use of quench plates. Were I do have a problem is a nasty little visitor to the party called thermo-dynamics. I can not understand a consistant HT with two or more seperate parts so proximate to each other. Where is Mete ? When ever I ask for him he usually expains I am the one that is wrong. I'll take it if he'll chime in here.

RL
 
OK two more Cents..:)

Just thinking about it and not doing it would make me think warpage
from the fact that if you heat from one side more than the other
you'll get the steel to bend( stress ) in thinking that way
what's the difference in cooling? ( unheating if you will )

with two blades side by side at 1/8" and not supported
as in a piece of 1/4" would be as one piece.
one would not keep the other from warping (stresses )
I think the only thing over riding the whole issue is the
plates are keeping the steel straight through the process
kind of like sticking boards while drying to keep them from warping.

I think the plates are drawing fast enough from the edge mainly
because in quenching
in what I read is not suppose to be cooled too fast ( cracking is possible)
it was to be done on a rack with moving air
I use a can with compressed air
because I don't want to remove them from the packet possible
causing scale and I still I want them to cool at a comparable rate as on the rack.
 
FWIW, 4 pre-ground 3/32" blades in 2 packets, stacked and quenched with plates are hard no question. I was working on them and they are very hard to the edge. So I know, it does work. Maybe not as consistent a process as it could be, but I have personal proof that Peter and Kit are right.

------------------------------------------------

But being a constant tinkerer, how about a different approach for batches.

I don't think air cooling a large batch is a good idea (in or out of the packet). Plates cool faster than air, especially if the bevels aren't ground. But then there are all those open questions. So........

What about oil quench?

I could have a pan with warm oil and an inner basket (like the french fry machine at McDonald's). Then have, say, 4 blades in a pouch. Then cut the pouch and let them all drop in warm oil at once and agitate the basket.

This would avoid the delays of fumbling around getting the blades out of the bag.

Thoughts?

Steve
 
Originally posted by Sando
What about oil quench?

I could have a pan with warm oil and an inner basket (like the french fry machine at McDonald's). Then have, say, 4 blades in a pouch. Then cut the pouch and let them all drop in warm oil at once and agitate the basket.

This would avoid the delays of fumbling around getting the blades out of the bag.

Thoughts?

Steve
Click to expand...


yep works, I know of a large German manufacturer who heat treats their blades using salt and oil quench with a large basket...they do 20 - 30 blades at a time. All you have to be concerned with is the initiation of the martensite transformation...so look at the ttt diagrams and see what kind of time you have to get it down below the nose of the curve...much else doesn't matter.

Quench plates, good idea too, beveled blades or not.

:)

-Darren
 
I think it is Steve that uses plates and also forces air on the edge are. Now I do like that deal. I had never thought of that. I wonder now though, will the spine harden deeper than the bevel?

RL
 
Kit has a significant point here ,getting below the pearlite nose is important.In all the quenching the time from furnace to quench should be minimized. If you take it over to the work bench and fumble to open the packet you're losing time. I don't see any problem with quench plates. They do provide insurance against warping and providing that you have large enough mass such as 1" thick plates it should work OK as some have found. I wouldn't stack more than 2 blades high and again quickly go from furnace to plates and clamp quickly and firmly. Has anyone tried going direct from furnace to oil with blades still in the packet ?
 
Mete, I have not but since your question indicates it may be okay to do so I will try that.

Okay, on the quench plates, I give in. I'll try that too on a test piece. Too many makers bragging about them and after all I've never even tried it.

I think there is some bar-b-q sauce here. I like my crow that way.

Roger
 
Hey! Wait a minute - ok only a few seconds - actually how many?

We are all talking about air hardening steels and quench time. But I think I'm the only one that doesn't know how fast is fast!!!

ATS-34 I can't find a TTT diagram anywhere. What is the temp where pearlite starts to form and how long do I have to get below it and what temp do I have to get to.

In other words I have no idea what the curve looks like.

Steve
 
Good question

Steve, I haven't seen one on ATS-34 and in fact I have been using 154CM sheets for my reference. I think I tried searching for a good ATS-34 data sheet but believe I failed to find one. Regardless, I still haven't seen the graph for either. I hope too someone here has one to show us.

RL
 
Thanks, Mete.
I should have mentioned that the quench plates are primarily used on the CPM steels and they are 1" x 12" x 12".
I have tried oil quench with the blade still in the pouch. Wasn't happy with the results. Really see no reason to as you can snip the pack and drop the blade in (I use a mesh basket) the oil.

I've Rockwelled the blades front/back/each end after this process and find no difference in Rc.

I've often said it doesn't take a rocket scientist to heat treat the steels we use, but a dummy can't do it. You gotta take lots of notes and pay attention to results. I've been heat treating many years and still pull the notes down and check them before each time. I've also made alot of adjustments on them over the years. A good Rockwell tester, or access to one, is a must.
 
ATS-34 and 154 CM are ,for all purposes the same. Reading the heat treating procedure for 154 CM gives you a hint that it's not air hardening as an A2 or A10 would be. They suggest salt quench to `1000 F then air cool or oil quench so the pearlite nose is fairly close to the right. If you guys weren't so cheap you would get a vacuum furnace that would drop the blades right into the oil. In any case be quick.
 
If you guys weren't so cheap you would get a vacuum furnace
Click to expand...

hahhahah. (Funny part is I was looking on ebay.)

Seriously tho. How much time do I have on 154cm or ats-34 to get from 1975 to 1000 degrees? It sounds fast. Do I have 1, 2, 5 or 20 seconds?

Thanks,

Steve
 
Originally posted by mete
If you guys weren't so cheap you would get a vacuum furnace that would drop the blades right into the oil.
Click to expand...

Mete
if you got one or two hanging around
go ahead and ship one to me
can't be more than a few Bucks
I'll pay the shipping hehehehe :D :D
 
I can't remember the name but there has been a Crucible metallurgist on this forum, he's the man to ask for TTT curves.....Have you guys seen the Andrew Jordan thread on the custom knives section ? Nice way of marketing..... Has anyone used , for experimenting or demonstrating damascus, different colors of playdough ? An easy way to experiment.
 
Originally posted by Kit Carson
I've often said it doesn't take a rocket scientist to heat treat the steels we use, but a dummy can't do it. You gotta take lots of notes and pay attention to results. I've been heat treating many years and still pull the notes down and check them before each time. I've also made alot of adjustments on them over the years. A good Rockwell tester, or access to one, is a must.
Click to expand...

Kit, surely you don't really need a Rockwell tester. Can't you just gauge it by eye, like a real bladesmith would? ;) [don't answer that... I'm just stirring the pot in an old thread]

Originally posted by Ed Fowler
http://www.bladeforums.com/forums/showthread.php?s=&threadid=268912
Does science lead and the art of the blade smith follow, or can it be the other way around?

When I started forging blades I purchased a number of texts devoted to the science of metals, I made up cue cards with the science on one side, and the definition on the other. One day I came to the conclusion that the science was interested and came from metals designed for other uses than cut.

I tossed the science into the slough in front of my shop and began to explore the simple world of the knife, free from the traditions that the science treads in.

Rockwell alone does not predict cut, some hold on to Rockwell tests like a drunk holds onto a lamp post for support, while it is useful to some, there is more to cut.

The search will be very discouraging when the steel used varies, Every batch of steel is different. When working with the same steel by number from different manufactures each will vary.
Click to expand...

-- signed, an unbalanced drunk,
rdangerer
 
The hardness test gives you the assurance that you have heat treated properly. Relating hardness to edge retention is not all that reliable. The best example is talonite where hardness is low but edge retention is high.
 
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