Triple quench secrets to be revealed?(or not)

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Pig
I just added the URL to the page then see that you had done that
already..
you can differential heat treat SS but it's a pain to do
in comparison to High carbons.
 
Hey all,

Most of this discussion is over my head. I'm not sure if the "single quench guys" feel that the triple quench process produces a different structure in the steel, or that it's just a more labor intensive way to reach the same results? IMO, if the only difference is visual then the extra time would be worth the effort. Part of the appeal and art of Ed's knives is in the etch.

Mete, you wrote "The tetragonal crystal (elongated cube) of martensite..." It's a bit difficult to make out the features from this pic, but is the pattern near the spine of this blade "tetragonal crystal formation"?

orig.jpg


I came across this page on your website, Kevin. Do you fully harden all your blades?

-Jose
 
Jose, no. You wouldn't typically see martensite with your own two eyes. You would need a microscope. What Mete is referring to is a different effect. Though, it is possible for some martensite to be mixed in with that structure, but that is another matter.

That knife is 52100 I would assume? So, my guess would be segregation and the subsequent banding of proeutectoid cementite and other carbide due to the direction of working. Anisotropic effects that are visual are quite pretty. Being hard edge and soft body, the etch "digs deeper" in the soft portions, so it shows up better than the edge.

Kevin is better at explaining metallurgy in simpler terms, sorry that's the best I can do. Maybe he will chime in. :cool:
 
Greymaker , tutorial is now in the hands of Kevin. This will be a general one .Will not cover forging or 1 vs 3 quenches--- maybe Volume 2 !.....Jose , you're someone who needs to study my tutorial. You could never see the crystal structure with the eye, since you're talking about the size of just a few atoms.We check it with xray diffraction... I assume that the photo is that of an edged quenched blade where near the edge you will have martensite and the slower cooling spine would be pearlite. The two different structures would then grind and polish differently and thus show different textures.
 
Originally posted by Jose Reyes
I came across this page on your website, Kevin. Do you fully harden all your blades? -Jose
Click to expand...
The page Jose refers to on Kevin's site is a (nice) discussion about salt baths, one hot for austenizing and another cooler, for a ~ 400degF quench.

Jose, I can't, and of course am not trying to, answer for Kevin.

But in general, a 'smith can use salt bath(s) for the austenizing heat and quench, and then draw the spine back with, say, a torch to soften it up.

But that brings up another question... any reason to temper in salts, same ones you use for the 400F phase, just maybe 50-75 degF cooler after the blade comes to room temp? Or do most of those who use salts just temper in an oven? (the oven, maybe for one good reason, to keep the salts available for the other operations).
 
Thanks Mete
Kevin,,, nice write up on the salt baths

again would you mind if I use it too :D thanks
 
Hey all,

Thanks for the info guys. I try to do some research but it's hard to find the time right now. I'm in the process of reading through Kevin's website, he does explain it to the layman very well, but there's still a lot of information for me to digest. :)

-Jose
 
Mete, thanks for the reply concerning the S90V tempering question.

I'll try to keep stainless out of this thread from here on. Thanks for all your patience on this one.

RL
 
rlinger,
please, feel free to talk about stainless by all means.
Opinion of mine (about stainless)is only one single opinion, all opinions are as good.


pig
 
okay,,,,I have started to forge John Deere load control shafts because of you guys...

and...

I just got my first real gas forge and have left behind my home-made coal forge to rust in the snow....

I will walk in the steps that Ed Fowler has made to see where it is that he is going....But I do yet have this one question...

Ed was asked about the way he now heat-treats his 52100 steel and his answer was given as this -

ed said -

"After the forging was complete, two blade smith normalizing heats:
heat to critical, confirmed by a magnet, hold blade in a shaddow, it will turn dark, then brighten, then reheat to critical again, be careful to keep the tip from over heating and cool the blade in a shaddow, watch the the colors change again. The blade will be magnetic at this point.
Full normalize heat, to critical, check with a magnet and allow to cool to room temp. in still air. Don't hurry it let it cool slowly.

Then three blade-smith anneals (that is what I call them). Heat to 800 degrees, hold for two hours and let them cool down slowly. (I do this in three days, 24 hours between heats, in the house hold freezer over night.

Many question the 24 hour cycles, I use them because I believe in them, steel takes time to enjoy where you want it to go, tincture of time has never hurt.

Grind the blade evenly, right side, left side.
Take the blade to a 220 grit finish. Any deeper scratchs can influence the grain structure below the scratch.

Texaco Type A quechant is the oil I use for 52100 and 5160. You can purchase some from Shane Justice. If you use any other oil we are not on the same page.

The specks call for heating the oil to 135 f. I speed my oil up just a little by heating it to 165 f. (I experimented with oil temps a lot to figure this out, you may need to experiment on your own to find what works best for your blades.)

Heat the blade to critical, catch it right at critical or a little above, if you allow it to cool, it will remain non magnetic but be too cool to harden. Use the magnet religously!
Quench the blade in the oil to the depth you wish to harden. When it quits fuming, fully submerge the blade in the oil and allow the oil and blade to come to room temp. Blades then go back to the home freezer overnight. I try to keep 24 hour cycles. repeat the quench cycle for a total of three quenches.

I then temper the blades, again three cycles 24 hours apart. I believe that more time between cycles would be of benefit, but remember we got to make a profit!

The first tempering temp is 330 f.
Grind off a little of the edge flat to get to the best edge possible, then grind the blade to its final edge.

I test this edge, edge flex, then cut. If the blade chips on the flex test, I temper higher. Depending upon the nature of the chips I may to as high as 10 degrees for the next three tempering heats. Then test for chip again, if it chips try a higher temper temp. if not, test for cut.

The nature of the blade dictates how you need to treat it. It leads you through, if you try to lead, she will let you down.

The above is the basics, we can go further if we chose."
_________________________________
But guys....

BUT....what I need to know now is, what changes to this listed heat treatment would you guys suggest for my 5160 steel?...(in keeping with the Fowler teachings on the need for triple HT/ quenching)
 
mete & Greymaker:

I recieved your attached write up on Friday, unfortunately I have been out of town since Thursday. I just got back tonight and have not had time to look it over yet. I will get to it ASAP. I also apologize for my absence to any others present who wanted to reach me.

I cannot believe how full my e-mail can get in 4 days!
 
DaQo'tah Forge,

....temper the blades, again...???

You did not list in your detailed procedure the first temper cycle. Have you?
Are you sure not waiting some 24 hours after quenching and before tempering?


pig
Click to expand...
 
Originally posted by Jose Reyes


I came across this page on your website, Kevin. Do you fully harden all your blades?

-Jose
Click to expand...

Yes. My approach puts emphasis on strength instead of ductility, with a strong attention payed to edge holding. Simply put, I like to make knives that will break, but in order to break them you need to put more force into them than what a human arm should be able to generate while using it for a chopping, slicing or thrusting blade. I prefer this to a soft ductile spine that bends with moderate pressure.
 
Originally posted by rdangerer
The page Jose refers to on Kevin's site is a (nice) discussion about salt baths, one hot for austenizing and another cooler, for a ~ 400degF quench.

Jose, I can't, and of course am not trying to, answer for Kevin.

But in general, a 'smith can use salt bath(s) for the austenizing heat and quench, and then draw the spine back with, say, a torch to soften it up.

But that brings up another question... any reason to temper in salts, same ones you use for the 400F phase, just maybe 50-75 degF cooler after the blade comes to room temp? Or do most of those who use salts just temper in an oven? (the oven, maybe for one good reason, to keep the salts available for the other operations).
Click to expand...

I use my low temp salts exclusively for tempering. THey have amny advantages over an oven or kiln. First of all they are right there, already heated up and waiting:). The temperature is very consistant and even. The thermal conduction is very fast, so you don't have to wait as long for a more thorough temper. I could go on, but lets just say that the low temp. salts aren't just for quenching ;) In fact, if you want those gorgeous colors on some fittings, the low temp salts share many characteristics with hot blueing salts:)
 
Originally posted by Kevin R. Cashen
Yes. My approach puts emphasis on strength instead of ductility, with a strong attention payed to edge holding.
Click to expand...
And therein lies the design choice, and sometimes choice of maker, the educated user needs to make for a knife's given scope of intended work. Strength (resistance to bending) or ductility (will bend but not snap, may take a set).
 
Kevin,

Thanks for the reply. Would the salt bath technology work as well if a maker wanted to make differentially hardened blades? Would using a torch to heat the spine "undo" the benefits of having the precise temperature controls, or are we talking about different scales of temperature where the steel doesn't undergo the same type of changes?

-Jose
 
Originally posted by Jose Reyes
Kevin,

Thanks for the reply. Would the salt bath technology work as well if a maker wanted to make differentially hardened blades? Would using a torch to heat the spine "undo" the benefits of having the precise temperature controls, or are we talking about different scales of temperature where the steel doesn't undergo the same type of changes?

-Jose
Click to expand...

Many differential hardening operations work well with shallow hardening steel. Salts at 400F+ have a slower thermal extraction rate than what 1084, 1095, W2 and others need. Clay coatings would slow things down all the more in a low temp salt and edge quenching would be very slow.

There would be no negative affect from finishing the entire blade with the salts and then drawing the spine back with a torch, the edge would be very preicisly done and have excelent strength characteristics.
 
Graymaker, all my emails to you are now being rejected .I'm a metallurgist not a computer geek .Tell me what to do .My system is windows XP.
 
I just want to know eds throw a blade in a snowbank heat treat.mabey rex could find out what the snow changed in the steel?sorry everyone, couldent resist...
 
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