Advice needed on l6 steel

csabacanada

csabacanada

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Joined
Sep 5, 2005
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Hello,everyone.I was wondering if I could get any info on L6 steel .I have been using knives for more than 30 years and I have tried almost every steel I could get my hands on .I tried to read as much as I could on knives ,knife making and different type of steels.My absolute favorite steels are forged 5160 and forged 52100.Recently I got some knives made of L6 buy Koyote and I have tested a bit the knives and I was really surprised how well they held up.This was the first time I have ever had knives in L6,so I was wondering if anyone could give me some info on L6 -how does it compare in toughness ,edge holding ,stain resistance with 5160.Any help would be appreciated.THANKS.ALL THE BEST
 
This is from Joe Talmadge in his steel FAQ

L-6
A band saw steel that is very tough and holds an edge well, but rusts
easily. It is, like O-1, a forgiving steel for the forger. If you're
willing to put up with the maintenance, this may be one of the very
best steels available for cutlery, especially where toughness is
desired. In a poll on the knifemakers email list back in the 1990s,
when asked what the makers would use for their personal knife, L-6
emerged as the top choice.
 
I use it a bit. It is like O1 in many ways and a bit tougher than O1 I'm guessing it's the vanadium. IMHO it is tougher than 5160 but it will wear a bit faster than 5160.
This is what I have for L6
Carbon: .07% to .09%
Chromium: .03%
Manganese: 1.4% to 2.6%
Nickle: 1.4% to 2.6%
Phosphorus: 0.025%
Silicon: 0.025%
Sulphur: maximum of 0.01%
Vanadium: 0.15%
 
L-6 is great for toughness as in choppers. It's the nickel that makes it tough. There are two makers , Carpenter and Crucible and they have different HT characteristics.
 
mete said:
L-6 is great for toughness as in choppers. It's the nickel that makes it tough. There are two makers , Carpenter and Crucible and they have different HT characteristics.
Click to expand...

Forgive me for getting side tracked, but how are they different?
 
These are the certs from the last batch of carpenter L-6 I bought.
If someone could post their certs from a crucible batch it would be helpful for comparision.
C .710
Mn .560
P .016
S .002
Si .410
Cr .920
Mo .300
Cu .150
Ni 1.75
Fe Balance
Thanks,
Del
 
delbert ealy said:
These are the certs from the last batch of carpenter L-6 I bought.
If someone could post their certs from a crucible batch it would be helpful for comparison.
C .710
Mn .560
P .016
S .002
Si .410
Cr .920
Mo .300
Cu .150
Ni 1.75
Fe Balance
Thanks,
Del
Click to expand...

Del, got their website handy????
 
Hello mete, we finally got our power back here in Michigan:)

L6 is a chemistry range that looks like this:

.65% -.75% Carbon
.60% - 1.20% Chromium
.25% -.80% Manganese
.50 Molybdenum maximum
1.25% - 2.00% Nickel
.030% Phosphorus maximum
0.03% Sulfur maximum
.05% Silicon maximum.

Suppliers have large customers they have to keep happy thus if several thousand parts suddenly come back broke or too soft there can be trouble. I have received chemistry as well as origin sheets from both Carpenter and Crucible, and while both are having the steel made in various foreign mills they are working with mills that produce very different chemistries within the allowable range.

Crucible’s L6 (champalloy) typical chemistry:
Carbon: 0.75%
Manganese: 0.70%
Silicon: 0.25%
Chromium: 0.80%
Nickel: 1.50%
Molybdenum: 0.30%

Carpenter’s L6 (R.D.S.) typical chemistry:
Carbon: 0.70%
Manganese: 0.35%
Silicon: 0.25%
Chromium: 1.00%
Nickel: 1.75%

Carpenter R.D.S forges a little smoother and is friendlier to folks trying to anneal and heat treat if they have not experienced L6 before, however they only offer in flat bar that is often in sizes not friendly to knifemakers, and can be twice if not three times as expensive. Crucible Champalloy is much cheaper but is sold only in rounds and is not for the feint of heart if they have not dealt with such an alloy before. Moly is a very powerful alloying element and that small difference makes huge changes in the hardenability, Ms temp, and how hot you have to go to temper. This with the added Mn makes it so the steel can reach 61HRC if you heat it up and toss it on the floor. Neither have any Vanadium and if an L6 has V, I would have to say that it was a rare custom melt.

If you have saw blades, it is not safe to say you have L6, if you have saw blades it is only safe to say that you have “saw blade” steel, many large band saw use alloys closer to 15n20 and these days it is much more cost effective to use a much lesser alloys in the body of the blade and special inserts for the teeth.

I have used L6 for most of my career and for large blades it is my preference (and I use Champalloy when I can), the impact toughness is through the roof compared to other common blademaking alloys like 10XX or 5160. For smaller cutters I prefer O1 for its edge holding. Those deciding to use actual L6 need to study up on spheroidizing if they want to save their tooling, and the steel also responds better with tight temperature and time controls.
 
Kevin,
Carpenter also sells rounds and at a much lower price.
The certs above are from a batch of flat that I bought a couple months ago. Paid $9 a pound, But I normally get 1" rounds at $3.28 per pound.
They do occasionally offer 1/4" flat stock, But it is usually $10 per lb.
Thank you for posting the info on crucible, I know that you deal with them more and that they have more local outlets, which makes them easier to deal with for some. I have dealt with carpenter for awhile now and found them to be extremely helpful.
Thanks,
Del
 
Thanks for everyone for help and I WISH A WONDERFUL AND HAPPY NEW YEAR FOR ALL OF YOU.TAKE CARE:thumbup:
 
delbert ealy said:
Kevin,
Carpenter also sells rounds and at a much lower price.
The certs above are from a batch of flat that I bought a couple months ago. Paid $9 a pound, But I normally get 1" rounds at $3.28 per pound.
They do occasionally offer 1/4" flat stock, But it is usually $10 per lb.
Thank you for posting the info on crucible, I know that you deal with them more and that they have more local outlets, which makes them easier to deal with for some. I have dealt with carpenter for awhile now and found them to be extremely helpful.
Thanks,
Del
Click to expand...

Del,

What is the number to call for Carpenter? I looked on their website, and it wasn't clear.

Thanks,

Phillip
 
Phillip,
the # is 18667909092
There are 2 ladies that work in that section and they both are very helpful, just let them know what you need.
Thanks,
Del
 
Kevin R. Cashen said:
If you have saw blades, it is not safe to say you have L6, if you have saw blades it is only safe to say that you have “saw blade” steel, many large band saw use alloys closer to 15n20 and these days it is much more cost effective to use a much lesser alloys in the body of the blade and special inserts for the teeth.

I have used L6 for most of my career and for large blades it is my preference (and I use Champalloy when I can), the impact toughness is through the roof compared to other common blademaking alloys like 10XX or 5160. For smaller cutters I prefer O1 for its edge holding. Those deciding to use actual L6 need to study up on spheroidizing if they want to save their tooling, and the steel also responds better with tight temperature and time controls.
Click to expand...

I need to be clear, because I use a LOT of 15N20- it's my steel of choice for smaller blades. I have some Ancient, old, really old pieces of bandsaw stock that are L6, and act like L6 (which doesn't act like 15N20, especially on my poor drill bits), but the thicker blades like Csabas are all purchased L6.

And to add to the confusion, I also use 8670m! (and find it to be stone cold easy to HT well and very durable.) 15N20 and 8670M both do a lot of what L6 does for blades for me, but aren't the same thing. A lot of people call the 15N20, 8670m, and M2- L6 variants, and I stand moot on that. They don't behave the same for HT or annealing. I know that I am less nervous working with both of those, since I've been warned so much about the difficulties of L6, but thus far I've had some good L6 blades come out. Oddly, and Kevin, maybe I'm high, but it seems easier to get best results with my limited technology on thicker blades rather than thinner.


I find that I have best luck in my environment annealing L6 by heating some scrap rebar and placing it very close, but not touching, in with L6 in the vermiculite bucket at the same time. And barring a sudden aquiring of a 24 inch kiln, that's what I'm stuck with.
 
mete said:
Crucible L-6 is air hardening, Carpenter is not.That means things like normalizing and annealing are different.
Click to expand...

L-6 is an OIL-HARDENING STEEL!
either formula in thin sections like we knifemakers use gets very hard when cooled in air and this can play merry hell with tooling if not annealed properly. It is a borderline steel between oil and air hardening because of the chromium and nickel content, but the HT specs on it are for oil quenching.
According to crucibles website full hardness will not be attained in sections over 3 inches when oil quenching.

I have used carpenter L-6, uddenholms 15n20 and admirals 8670, all for differnt purposes and all with excellent results. I have also used 203e and even 8620 for some projects.
Del
 
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I don't think mete meant to imply that the steel was designated air hardening and I am sure he knows they were designed for oil, but any of us who have worked it know that just air cooling the steel can get you to hardness levels other steels would obtain from quenching (I imagine we could see a few plate quenching of L6 threads shortly after this). Since I have a number of steels that I forge down to dimensions before working with them, I often will have some confusion about the pieces on the floor, this is always quickly resolved by doing a quick Rockwell test on them, if it is 1/2" thick or better and exceeds 56 HRC after just being thrown on the floor to cool, I know it is Champalloy.

This is not to say that you have a good clean homogeneous martensite from such a heat treatment, due to a huge bainitic nose on its curve and virtually no pearlite zone you most likely have a nasty, unpredictable mix of martensite and a lot of bainites, and not all bainite is good, lower bainite may be fun for some but upper bainite is not desirable at all and it happens to be the quickest to form. I have done some experiments with making my own lawn mower blade inserts and such with L6 and the ones that I decided to take a short cut on and just allow to air cool had no better strength or toughness than any other steels, but the ones that were heated, quenched and tempered properly have allowed me to run over just about anything with my mower and keep going.

Koyote, your points on the subtle, and not so subtle, differences from L6 to 15n20 and 8670M are spot on. For too many years I saw smiths says that 15n20 was just a European name for L6 when it is more like a 1075 with added nickel, and we all know the dangers of assuming that 8670M is L6;). Both the other steels should see better thoughness due to the common nickel contents, but each will have distinct differences in their heat treatments. L6 partners best with O1 in damascus but can give you some grief if mixed with some other steels. 15n20 partners quite well with W and 10XX series steels and the 8670M kind of straddles the line between the two hardenability curves. Yet all will give that nice nickel contrast that we like so much, although the 8670M is less striking than the other two with more of a light chromium gray effect on the pattern. To be honest if you are able to mill or drill Champalloy after simply cooling from critical in vermiculite, even with the hot rebar, I would have to see the papers from Crucible to believe it is that steel, and even then I would wonder if they made a labeling error after all of my experience with it.
 
The vermiculite and rebar "assist" is VERY hit or miss. And I have gone through way too many drill bits :( I've messed around with various methods, and ... well, it's hit or miss. For reference, it's 1 inch rebar, and a fair amount of it- and it works for crap on thin stock. I've considered piling some wool and cement in a spare steel box and using the rebar to keep some temperature control for a "cooling oven" but the heat loss from opening it up seems like it would kill the effect. I'm putting a kiln on my list, but since most of the L6 I actually do is large blades, I have to go all out for a big kiln. And cash money is really tight with wife in nursing school.

I have tried very hard to avoid the "everything with nickel is L6" fallacy, mostly due (with much thanks) to kevin and mace kicking my butt on terminology very early on a couple years ago. So I try to be exacting on the differences, but in truth I think that all three of these steel make excellent "monosteel" blades.


If I ever find a good source for the mythical .120 15N20 stock, I'll put my son in hock and find a way to grab a couple hundred pounds!
 
Keith H, Originally each steel mill made their own steels. Gradually standards were set up .The last of these were for tool steels .You still see mills call a steel by a name [Champalloy] in addition to the designation [ L-6].A mill may still have the practice of melting to a certain chemistry within the standard especially as far as optional elements which appear in tool steels.
As these posts show - be specific about a steel , the source and the HT.
 
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