L6 steel questions...

B

big no-no

Joined
Nov 7, 2003
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44
Would any of you knife makers out there consider using L6 to make a drop point blade 4.5" long x 1" wide x 3mm thick with a full tang and either a scandinavian grind or flat grind? Is there something better for such a blade? I would anticipate using this knife as a hard-use-but-not-abuse bushcraft knife. Ease of sharpening is of paramount importance. Some other materials I have looked at include: 5160, 52100, 1095, A2, VG10, and INFI. I get lost in all the technical details and wind up losing sight of what it is I want the steel to do for me. I need your help to see the forest through the trees.
 
All of those steels will make a great knife. You need to pick one and use it for most of your knives until you get the steel mastered. Most of the difference in those steels will be in how you plan on making the knife (forge/grind) and how you will do the HT. L-6 would be a good choice.
Stacy
 
Properly heat treated, L6 makes about as good of a blade as anybody needs.
 
Mr, no no, steel selection is something that too many would be makers don’t study enough and as a result there are also a lot of established makers that really don’t have much rhyme or reason in there choices of blade material. There are some good guidelines to follow in the chemistry of steel that will help match it for its use, and I have a whole section in my notes that I used when teaching bladesmithing.

L6 is a great steel but one has to note in what area it is great in, and the secret is in the nickel and some of the chromium. This chemistry makes it very impact resistant and able to handle stresses that other steels cannot, the steel can take and hold a good edge but it really proves itself best on longer chopping blades.

For your applications you will be looking at the balance you want between impact toughness and abrasion resistance. As the blade gets longer impact toughness becomes more important, as it gets shorter abrasion resistance can then be safely relied upon. Abrasion resistance is a result of hardness, and the primary factor is the overall hardness as a result of complete martensite formation in the quench. However any steel with a carbon content of approx 0.7% or greater will achieve the maximum hardness, beyond this some steels will outperform others by the added abrasion resistance of carbides. One must have in excess of 0.8% carbon in order to achieve full martensite hardness and also get leftover carbides, the more extra carbon you have the more abrasion resistant carbides. But extra carbides will also lean things towards the brittle side unless great pains are taken to overcome this. This is why 1095 will hold an edge better than 1084, but the 1084 can be tougher. If one wants toughness at higher Rockwell hardness then carbon alone cannot do the job and that is the function of the other alloying elements.

The words “ease of sharpening” are an immediate red flag to me in the area of edge holding. I always wonder what folks definitions of this are, and why something that is often by definition counterproductive to edge holding is such a priority. One sharpens by abrading, and edges go dull from abrasive actions, so saying the edge is easily shaped by abrasion is the same as saying it will be easily worn down in use. Much of this issue can be solved by bringing in the most overlooked factor- edge geometry. Since any abrasive stone is many orders of magnitude harder than a hypereutectoid steel, even as-quenched, there is no reason the abrasion resistance needs to suffer, and with diamond hones it is safe to say no knifemaker on earth can hope to approach these hardness levels. Every single blade I ever found difficult to sharpen was due to and lousy edge geometry, if you need to hog away massive amounts of hardened steel just to hit the same angle as the actual edge, sharpening will be a real pain in the @$$ (ironically enough often makers with less confidence in a rather soft blade tend to make these overcompensated bulky edges). If the edge is fine and strong with a low angle, any stone will quickly engage it and have it very sharp in just a couple of passes. To me “easy to sharpen” is too often a makers way of putting positive sales pitch on the fact that their heat treat could be better.

Now that I have forced you to read my babbling tome, I would say I would opt to go with the 1095 for a blade that size, I would also say the 52100 but the more tests that I do on that steel the more I realize that it really needs some special attention to do what a simpler steel could accomplish without the bother. The other steels delve into the realm of stainless and air hardening and that has no iterest for me so I will leave them to folks how play with them more.
 
KRC,
Thanks. That is exactly the kind of input I was looking for. I visited your website. If I ever decide on a custom job, you are at the top of my go-to list. As far as the knife I am describing above, what steel would you use? Assuming I don't beat the edge to death in between sharpening, but instead maintain the edge after each use, then ease of sharpening shouldn't be too much of an issue. Also, are you familiar with INFI? Is this really anything special?
 
INFI is steel used by and only by busse knives with a secret blend of Nitrogen added. You would need to hire ninjas to break into the busse combat workshop to get any. (It is most likely similar to D2 is heat treatment i guess). One thing that is good about L6 is that you can get a large batch of it from a saw mill blade. the L stands for Low alloy meaning that it does not have high quantities of Molybdenum, Chromium etc. It does make a nice blade none the less.
 
There may be one thing not clear here. Are you considering making this knife yourself? Or ordering it as a custom knife?
Stacy
 
I am contemplating having a knife made to my specifications if I cannot find a production knife that meets my needs, so right now it is up in the air since I am still looking around. Currently I have my eye on the Skookum Bush Tool.
 
L6 is not a super fancy steel for a custom knife and will rust faster than most other tool steels. Use O1, A2, D2, W1, 440c, 154cm, ats34, 10xx, 52100 or a good damascus -the list goes on...

the maker will know what steel is best used for the knife and the one that he is most comfortable with. good luck.:thumbup:
 
I disagree that L6 will rust faster than many of the steels you listed. O-1, 10 series and A2 in particular come to mind. In my experience O-1 rusts at some mutant speed and 10 series steels will rust quickly if clean. A-2 I would say is on par with L-6 and seems to rust relatively quickly.

Now, all of that being said, many folks here can remember when even store bought knives were often made from carbon steel. The rust didn't stop us from buying and using the knives, we just knew how to take care of them. By the way, I'm not all that old either ;)

I'd focus my selection on the maker and not the steel. Every steel listed by every person on this thread will make an incredible knife, especially if it's done by an incredible maker. Super fancy doesn't necessarily equal "good knife" so don't feel like you have to follow any trends.
 
One of the great urban legends is that saw blades from lumber mills are L6. Mostly, here in the Pacific Northwest, they are not. Check with the supplier to find out what it is. Most of the sawplate being used for bigger blades is 8670 modified. Bandsaw steel is mostly Uddeholm 15N20. And the really big blades, who knows. A few years back I scored a 5 1/2 foot diameter blade that had broken in half while running at full speed. It was pretty exciting but no one was hurt. I thought I had a real score. An analysis showed that it was 8620. That's what some rifle receivers are made of, but no steel for making knives.

If the mill is still in production, check with the saw shop and see who the supplier is. From there, call them and ask what they are using for saw plate or bandsaw steel. That's the only way to know whether it's L6 or not. And it's probably not.

Gene
 
Gene Martin said:
One of the great urban legends is that saw blades from lumber mills are L6. Mostly, here in the Pacific Northwest, they are not. Check with the supplier to find out what it is. Most of the sawplate being used for bigger blades is 8670 modified. Bandsaw steel is mostly Uddeholm 15N20. And the really big blades, who knows. A few years back I scored a 5 1/2 foot diameter blade that had broken in half while running at full speed. It was pretty exciting but no one was hurt. I thought I had a real score. An analysis showed that it was 8620. That's what some rifle receivers are made of, but no steel for making knives.

If the mill is still in production, check with the saw shop and see who the supplier is. From there, call them and ask what they are using for saw plate or bandsaw steel. That's the only way to know whether it's L6 or not. And it's probably not.

Gene
Click to expand...

I felt the need to thank you for this Gene, this is one of the biggest trouble shooting issues I encounter regularly with folks bent on using scrap steel. The trouble is that folks will contact me because they heard I work with L6 (and I do work with REAL L6) and ask what they may be doing wrong in the heat treatment due to their results. I will often happily spend much of my time trying to help them, but when all possiblities are exhausted and I finally ask them where they purchased this "L6", only then do they tell me it was an old saw blade:mad: This is one of the reasons I am such a grump about using old unkown junk for a process that requires knowledge of the material. I feel it would only be honest to refer to actual L6 with chemsity as L6 and old sawblades as "old saw blade" until you get it analyzed and have an L6 chemistry go allow you to call it L6.
 
Ok, fine L6 does not rust that bad, im just saying that it is not any better than VG10 or INFI.
 
I won't say that it is a universal characteristic of L6, but I had an old sawmill blade knife (that was advertised as L6) that was difficult to sharpen without being particularly hard. It wanted to form an obtuse burr that was very hard to get rid of. I think it was due to that nickel and chrome being hard to cut cleanly. I had to put a microbevel on the blade using an extra-fine diamond hone to get rid of it. Even then it was not truly up to my normal sharpness standard.

When I say that I want a blade that is easy to sharpen I am partially talking about geometry and partially talking about the refinement of the blade steel. I would consider 1095 at 62 RC or A2 at 60 RC as easy to sharpen since I can easily get a razor edge on those alloys. I would consider badly heat treated 440A to be hard to sharpen. It is not that these things are hard to abrade, it is that they are hard to sharpen--well.

PS. I really enjoy 1084 and would suggest it to someone who wanted "ease of sharpening".
 
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