L-6 experiments

Phillip Patton

Phillip Patton

Knifemaker / Craftsman / Service Provider
Joined
Jul 25, 2005
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5,312
Hi guys,
Awhile back I bought a bar of L-6 from Crucible and just got around to making my first test blades out of it. I made two blades, one triple quenched, and one given a textbook heat treat.
I don't want to start an argument on triple quench vs. single quench. There's already been a lot of discussion about that, and it never seems to go anywhere, in my opinion.
I just finished the testing today. Is anyone interested in the results?
 
Ok, I knew someone would want to know. :D
I forged them both from 1" round bar, and normalized them both 3 times.
Then I annealed them in my evenheat oven. After which they were actually soft enough to drill. Then I ground all the scale and hammer marks off, leaving the edge good and thick to account for decarb. For the single quench blade, I put it in the evenheat oven, which had been preheated to 1510 F and left it in for 12 minutes. It takes 3 or 4 minutes to come up to heat, so I figure it was soaking for 8 or 9 minutes. Then quenched in oil. The triple quench blade was brought up to heat in my forge and soaked only long enough to be heated evenly. After quenching in oil i gave it a snap temper then left it in the freezer for 24 hours. The repeated for a total of 3 cycles. Both blades were tempered twice at 375 for 2 hours, freezing between tempers. I'll let you all read this while I type in the test results. :)
 
I ground them both to a pretty thin edge ( as similar as possible) and hand sanded to 400 grit and etched them. The etched pattern was almost identical on both of them. Since these are the first L-6 knives I've done, I couldn't tell if it was good or bad. :) Then I started cutting rope. I buy 1" hemp rope, and then unwind the strands, because I prefer cutting 1/2 rope to 1". So if you use 1" rope for cutting tests, divide my results by 3:D
I repeated the cutting test 3 times for both blades.

Single quench blade averaged 153 cuts.
Triple quench blade 156 cuts.
Not much difference.

In the next post, the bend test. :D
 
Well, the ATTEMPTED bend test. Sheesh, I've heard that this stuff is tough, but man alive! i did the triple quench blade first. I put it about 1/3 of the way in my vice and put a 22" cheater pipe in the tang, and almost pulled my workbench over, but the blade slipped out and flew into the air. It bent almost 75 degrees or so before slipping out. So i put it back in the vise this time about 1" from the tip. This time it broke. Which is exactly what I expected it to do the first try.
Then I did to same thing with the other knife. Put in vise, crank until it flies over my head, try again closer to the tip.
looking at the fracture, the grain on the triple quench blade is noticeably smoother and finer than the single quench, although both look very good to me. i think the triple quench blade was a little more difficult to break, which would make sense considering the finer grain.
My conclusion is that triple quench is not worth the extra time and effort with this particular steel.

Any comments questions or complaints? :D

P.s. i was really disapointed that they didn't cut better. The first blade i made from Dan Grays john deere 5160 made over 500 cuts on the same rope.
With the l-6 having more carbon, I would have expected it to do better.
Did I do something wrong?
 
Why did you heat one in the oven and one in the forge? I ask because this would seem to add more variables to the test. If you are triing to test triple vs. single quench then everything sould be kept as close to the same as possible except for the number of quenches given each blade. Also why the "snap temper" between quenches for the triple quenched blade?
 
burke531 said:
Why did you heat one in the oven and one in the forge? I ask because this would seem to add more variables to the test. If you are triing to test triple vs. single quench then everything sould be kept as close to the same as possible except for the number of quenches given each blade. Also why the "snap temper" between quenches for the triple quenched blade?
Click to expand...

This wasn't really a test between 1 quench vs. 3 quenches, this was a test between the traditional heat treat (i.e., longer soak time) vs. the untraditional triple quench method. I'm sure if i did the single quench the same way I did the triple quenches (quickly, in the forge) the triple quench would come out on top.
I've never used l-6 before, so not knowing what to expect, I did the snap temper just to keep it from cracking in the freezer. i don't think it would have mattered, and I don't do that with my other knives.
 
In fact, I just did an experiment where I forged two blades out of 5160, triple quenched one and single quenched the other (both in the forge)
and the triple quench blade did vastly better than the single quench.
I'm planning on soon doing the same experiment with 5160 that i just did with the l-6.
 
Did you get a chance to check the hardness on any of the blades? Since they are broken you have the opportunity to do some metallurgical testing if you have anyone near buy who can polish and look at the samples.
 
Satrang said:
Did you get a chance to check the hardness on any of the blades? Since they are broken you have the opportunity to do some metallurgical testing if you have anyone near buy who can polish and look at the samples.
Click to expand...


I don't have a rockwell tester, and I'm not sure the stakes are high enough in this case to justify paying someone to test them. Do you know how much that would cost?
 
burke531 said:
How about doing both in the oven with the prescribed soak times?
Click to expand...

You mean do one once with the soak, and another three times with the same soak time? That would probably result in some grain growth, but it might be worth trying.
 
Phillip Patton said:
I don't have a rockwell tester, and I'm not sure the stakes are high enough in this case to justify paying someone to test them. Do you know how much that would cost?
Click to expand...

Phill

I have a tester on my bench. I'll test them at no charge. If you want them back you pay the shipping. If you don't want the entire blade tested, just sent the broken off end. On my test knives I usually test three positions from cutting edge to the spine and about every 2 inches along the length. I'll mark the RCH on the blade with a fine point sharpie and send you .jpg file with the image.

Jim Arbuckle

If interested email me at a_r_buckle@hotmail.com or call 757-867-9578
 
You mean do one once with the soak, and another three times with the same soak time?
Click to expand...

Yep that is what I mean. As long as you don't go any hotter than 1510 grain growth should remain minimal.
 
Love L-6, lots of variables to work through though. I tested once with it triple vs. single quench and didn't notice much of an real differance. I don't have an oven yet and all my blades are heated in the forge or with a torch. After reading this I may have to do some more experimenting. I did get good cutting ability from it, about on par with the few 5160 knives I've made. For a hard use/abuse try to destroy it knife L-6 is my first choice.

Be interested in what you come up with, so keep posting results!
 
burke531 said:
Yep that is what I mean. As long as you don't go any hotter than 1510 grain growth should remain minimal.
Click to expand...

It'd be worth doing someday. Right now I'm doing 2 test blades each out of JD5160 and O1. I'll let ya'll know how that goes...
 
Will52100 said:
Love L-6, lots of variables to work through though. I tested once with it triple vs. single quench and didn't notice much of an real differance. I don't have an oven yet and all my blades are heated in the forge or with a torch. After reading this I may have to do some more experimenting. I did get good cutting ability from it, about on par with the few 5160 knives I've made. For a hard use/abuse try to destroy it knife L-6 is my first choice.

Be interested in what you come up with, so keep posting results!
Click to expand...


It sure is strong. I probably had 2 or 3 hundred pounds of force on those blades, and they aren't that big. What L-6 do you use?
 
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