L6 info wanted

Understand that there may be significant differences between the different makes !! Pick one brand, learn the HT ,and stick with it .
 
Karl, L-6 is one steel I prefer to forge wet. It will help reduce the scale build up. I found trying to remove it with the grinder was quite a chore and hard on belts. It also air hardens so normalizing isn't worth doing.
 
Thanks to a great tip from Don Fogg, I have started using sodium bisulfate to descale my forgings and I am much more pleased with it than acids. A few hours in the soak and all the scale is gone and my belts can tear up the freshly exposed steel without trouble.

If one is normalizing for the effects that industry often cites - softening, stress relieving and making pearlite then many alloys we work with need not be normalized. However if you are hoping for evenly distributing carbon and other constituents, evening out stresses, grain refinement and generally fixing much of the havoc you inflicted in the forging, then normalizing is very useful with L6 and many others. You just need to remember that pearlite will not be part of that process. Evenly heating to a proper temperature and then allowing things to cool evenly will do wonders for any simple alloys even if it does not soften it, but then softening is what annealing is for. Unlike 1075, L6 will not recrystalize properly at around 1000F because it will not make pearlite, you will need to cool to around 750F and allow upper bainite to do that same job. For grain refinement the air hardening tendencies actually work in your favor. The hardened steel will have a higher amount of stored energy and will recrystalize faster and finer than soft steel.

To all of this I would add that I have found normalizing to be come even more important with deep hardening alloys due to dangers of cracking and distortion due to cooling from an enlarged or uneven grain condition. Weld up a billet from O1 and L6 and reduce it to 1/2" thickness or less while it is still above 1600F and allow it to cool to ambient... trust me, you won't like what happens:(:thumbdn: But if you cycle that steel down after the hammering is done and allow it to cool to ambient with a nice and fine grain size and you will be much happier.
 
Hey Kevin, not to hijack this thread, but I just had an idea. I still have one of my failed L6 blades laying around. If I sent it to you, would you be interested in looking at it under your microscopes and see if you can tell what I'm doing wrong with L6?
If you don't have time, I understand.

Oh, and where do you get sodium bisulfate?
 
The chemical you can get any place that sells pool or hot tub supplies. As for the steel, you can send it any time but it could be quite a while before I could get to it for analysis, the metallography takes enormous ammounts of time in polishing and I have a back up of people I was to help out in this regard.
 
Kevin R. Cashen said:
If one is normalizing for the effects that industry often cites - softening, stress relieving and making pearlite then many alloys we work with need not be normalized. However if you are hoping for evenly distributing carbon and other constituents, evening out stresses, grain refinement and generally fixing much of the havoc you inflicted in the forging, then normalizing is very useful with L6 and many others. You just need to remember that pearlite will not be part of that process. Evenly heating to a proper temperature and then allowing things to cool evenly will do wonders for any simple alloys even if it does not soften it, but then softening is what annealing is for. Unlike 1075, L6 will not recrystalize properly at around 1000F because it will not make pearlite, you will need to cool to around 750F and allow upper bainite to do that same job. For grain refinement the air hardening tendencies actually work in your favor. The hardened steel will have a higher amount of stored energy and will recrystalize faster and finer than soft steel.

To all of this I would add that I have found normalizing to be come even more important with deep hardening alloys due to dangers of cracking and distortion due to cooling from an enlarged or uneven grain condition.
Click to expand...

Kevin, would this apply to 15n20 also, as it's similar in composition to L6? I've been playing with 15n20 and even after a couple normalizing cycles it's still almost too tough to file. Is the lack of pearlite a bad thing??
 
Kevin R. Cashen said:
The chemical you can get any place that sells pool or hot tub supplies. As for the steel, you can send it any time but it could be quite a while before I could get to it for analysis, the metallography takes enormous ammounts of time in polishing and I have a back up of people I was to help out in this regard.
Click to expand...

Ok, I'm in no hurry. Thanks!
 
Deweyknives said:
Kevin, would this apply to 15n20 also, as it's similar in composition to L6? I've been playing with 15n20 and even after a couple normalizing cycles it's still almost too tough to file. Is the lack of pearlite a bad thing??
Click to expand...

Actually 15n20 and L6 are very much different in composition, sometime, somehow, somewhere along the line bladesmiths got the odd idea that they were similar. I think it is the nickel thing, we tend to group steels together depending on what we use them for and due to the nickel the two steels are interchangeable for silver streaks in damascus. But other than nickel and around .75% carbon the steels are very much different. Just a little bit more chromium or moly makes a huge difference and L6 has a lot more.

I would heat treat 15n20 along the same lines as 1075 and ignore the nickel (after all that is what the carbon will do), however you may need to cool a little slower to lamellar anneal.
 
L6 and 15N20 are both bandsaw steels so they're easy to group together, and as you said they have similar carbon contents and both have nickel, I wouldn't say they're dissimilar. You can't heat treat them the same, sure, but similar is all a matter of perspective.
 
L6 actually has a wider array of uses than saw blades. A203E, and Admirals 8670M also have nickel but they are hardly interchangeble with L6 or 15n20. Both 5160 and 1095 have been used in spring manufacture does this make them similar? Different chemistry, different heat treatment but they look the same, from this perspective any ferrous alloy is similar :confused: For years I have seen bladesmiths refer to these steels as the same under different names, I don't get it? Folks loved the Admiral L6 alternative as long as they thought it was L6, I and some other folks pointed out that it didn't behave at all like L6 and then some people got it analyzed and found it was 8670M. Afterwards many were upset by this and felt it was bad steel that they no longer wanted to use it simply because it was not exactly L6. Most are fine with 15n20 being described as just a European name for L6 yet any of the 86XX series come much closer to L6 in chemistry than 15n20. This is just one fo those quircky human nature things that will always puzzle me, kind of like the number of people ready for a revolution when they pay $4 for a gallon of fuel and then crack open 16 oz. of tap water they just happily paid $2 for:confused:??
 
Karl, I apolagize for the hijack. I thought I was asking a simple question. :o

Kevin, thanks for the clarification. When I was searching for HT info for 15n20,one of the sites I was on stated the comparison as 'European version of L6'. :confused: I've never used L6 so can't compare from MY experience. I DO have a large circular saw blade tested as 15n20,digital oven and quench oils. Just trying to get the best I can w/ my abilities and equipment. Being free,I thought it would be good stuff to use to experment and develop some patterns and 'different designs'. But,I still want them usable! And if I don't like it, I did'nt waste a piece of O1 or W2. And if I work out a good HT, that's even better!! :thumbup:

Sometimes it's hard to wade thru the available information and decide what is fact, opinion, or just plain clueless babble. We're very fortunate to have guys around here that will step up and state 'what IS and what is NOT'. Your time and efforts are GREATLY appreciated!! :cool:
 
Karl you will find my detailed input to your original question in your request at the other forum.

Sometimes it's hard to wade thru the available information and decide what is fact, opinion, or just plain clueless babble. We're very fortunate to have guys around here that will step up and state 'what IS and what is NOT'. Your time and efforts are GREATLY appreciated!!
Click to expand...

Lots of opinions, I may be too guilty of that myself to judge, clueless babble is not as common as it would appear (thank goodness), the real culprit is assumption. For years one had to have special connections to get any good information on the odd practices that we dabble in so most guys made their best guess and worked off from assumptions. "I assume that saw is made of...”, "I would assume you could heat treat it just like...", "XXXX told me this and he has been doing it for 20 years so I assume it is right". But it became far too easy to substitute "I assume" with "I know", e.g. "I know it works because my blade skated a file and cut more rope than the last one." Repeat an assumption enough times and it will become known as fact. However, we now live in the information age; just about any topic can be researched in an instant, all the good information you could want is right there at your finger tips. At this point settling with our assumptions is just pure laziness. The catch is that it is just as easy to distribute bad information along with the good. That is why I am like a broken record about verifying facts. The internet could be the best tool we ever had for bladesmithing, or it could be the worst generator yet of bad information if we don't verify what we read. I have nothing new to add to the information pool, but I have spent many years verifying, so if I can help point out the false data so everybody doesn't have to spend the same years of verification, I am glad to help.

* Edited to add- Oh the heck with it, it only takes a second to cut and paste from the other forum and help keep your thread on topic:

Karl you may get some interesting customized recipes, but I have worked with this alloy the majority of my career and I can tell you that it is not one to get too "creative" with in the heat treatment. What is on the spec sheets seems to work best. Heating to 1500F and quenching in any medium speed oil works great. Tempering for knives works best in a range from 400F to 450F. If you need it tougher it is best to stop at 450F and go to 550F and go really tough instead of working in the 500F range. Multiple tempers seem to help out. There is a range that the chemistry can have, but the element to keep your eye on is the moly, if it has moly expect to have to temper at a slightly higher range than the L6 without it, also expect Ms to be a bit lower. Simply air cooling from a proper forging temperature will result in as high as 61HRC in sections as thick as 1/2"!!! Be prepared to spheroidize or don't even think of any kind of machining or drilling. L6 respond VERY well to martempering/marquenching and I believe you are sufficiently pragmatic for me not to have to bother mentioning austempering ;).
 
Last edited:
You must log in or register to reply here.
Back
Top