Best steel choice for big Bainite Bowie?

peter nap · Oct 5, 2003

Well.....5160 or 5160 and if you just have to change....5160.

Mete had a neat idea.....why not make a little damascus of L6, 01, and 5160, or if you want a super blend,
5160 and 5160 plus a little 5160

oh BTW, Rdangerer suggested:

Can also suggest you register at www.swordforum.com and ask those guys... Howard Clark uses this stuff in large sizes, others too probably

If you go there, they have someone running the board ...I forget his name but it was Rocky's girlfriend...ask him....and do the opposite!
:footinmou :footinmou :footinmou :footinmou sorry

Kevin R. Cashen · Oct 5, 2003

Originally posted by stevomiller
Everything that I've heard about Admiral's L6 is that it ISN'T. I have not used it personally but many reputable smiths say that it behaves nothing like Crucible's. I have also read many reports of it failing while being forged...

This is interesting to hear. I had a young man approach me at the Scagel hammer-in to ask for advice on how to work with the Admiral L6 he had. While talking he mentioned that after it cooled from forging he drilled it... I imediately interrupted him and asked if he meant that he had annealed it and then drilled it. He said no that he had drilled it right after the forging. I just looked at him and said "that aint L6!". Without a very good anneal, you will not like trying to machine or drill Crucible L6. I find it interesting to hear these stories because the chemistry that Admiral lists for the L6 is the same as that for Crucible Champalloy. Hmmm... I don't know, I get mine straight from Crucible and have never been anything but tickled pink with it, but then I have the equipment to deal with its quirks.

Keith Montgomery · Oct 5, 2003

I am starting to get very interested in this L6 stuff. Thanks for all the great info you guys.

rdangerer · Oct 5, 2003

Originally posted by mete
For those who don't know it's the nickel in the L6 that makes it tough...

I figured Nickel played into it, but I also suspected that Silicon played a role as well, mostly because the Shock resistant "S" series steels make use of a dose of Silicon as well. True?

Of course I ain't no metulurjist eether. Nor am I a metallurgist, hence the question. A couple of composition dumps, per Crucible:

L6:
============
Carbon 0.75%
Manganese 0.70%
Silicon 0.25%
Chromium 0.80%
Nickel 1.50%
Molybdenum 0.30%

S7:
==============
Carbon 0.55%
Manganese 0.70%
Silicon 0.35%
Chromium 3.25%
Molybdenum 1.40%
Vanadium 0.25%

S5: (added after Jason's post)
=============
Carbon 0.60%
Manganese 0.85%
Silicon 1.90%
Chromium 0.25%
Molybdenum 0.30%
Vanadium 0.20%

O1:
===============
Carbon 0.90%
Manganese 1.25%
Silicon 0.30%
Chromium 0.50%
Tungsten 0.50%

rdangerer · Oct 5, 2003

Originally posted by Kevin R. Cashen
I have a 50 Ft lb. charpy tester, ...have tested both O1 and L6 pieces in blade cross sections. The O1 has absorbed around 21 foot pounds in 1/8" thick blade shape cross section, and 8 foot pounds in 1/8" flats notched.

The L6 in the same shapes and sizes, in unnotched tests, maxed out the tester, even with multiple hits! It required around 21 Ft lbs to break the notched bar. Weakened by the notch, the L6 behaved like unnotched O1, but unnotched it was unbreakable even in a fully quenched tempered martensite condition. Marquenched, it would max out a much larger tester...

Excellent post, excellent information! There may be others, but I believe this is the first bladesmith I've heard about who actually has and uses a Charpy tester. I'm impressed. (Somehow, I suspect you own a Rockwell tester also).

(I'm one of those naive drunks holding onto the Rockwell lamp post for one form of support

:footinmou

)

And I appreciate hearing the results also. They are relatively consistent with what Crucible lists for material properties. While I'm not surprised the actual numerical values are different (different test sample sizes), the relative magnitudes are in line between O1 and L6 Which is logical, just a bit contrary to what some other makers have suggested, something along the lines of "you can't look at Crucible's data... everything changes when it comes to a sample the thickness of a knife blade" or somesuch.

The materials science realm is rich with content and insight for the open minded bladesmith.

Kevin, thanks for posting. I've learned more from you and Mete in the past couple weeks than I have on the forums for a good while.

Don't suppose you varied hardness and captured the impact toughness esults at various hardnesses? Yeah, I know, lots work... had to ask though.

Now, if we could get one of you metal beaters to really give CPM 3V a fair try (not at the forge per se, but stock-removed and tested, or a sample in comparison with L6).

Jason Arnold · Oct 5, 2003

You could paint on some WWII tiger teeth.

Jason Arnold · Oct 5, 2003

S5 works very well austempered. S7 wasn't designed for such.

the possum · Oct 6, 2003

Thanks for all the replies, guys. I've been too busy at work to make the calls to the makers I had in mind- will still try.
Kevin- Thanks again for the info. I learn something every time you post. From where I stand right now, you may be correct that tempered martensitic L6 will be adequate for my needs, but I'm rather gunshy from so many toughness problems I've had with my knives in the past. "Overkill" is exactly what I want this time! I've learned that when I've got adrenaline pouring thru my veins, I can do things with -and to- big blades that I could never duplicate in testing.

rdangerer · Oct 6, 2003

Originally posted by the possum
...but I'm rather gunshy from so many toughness problems I've had with my knives in the past. "Overkill" is exactly what I want this time! I've learned that when I've got adrenaline pouring thru my veins, I can do things with -and to- big blades that I could never duplicate in testing.

(I'm not trying to be obnoxious when I say this) ==> assuming that you don't have heat treat problems to work out at the root of the toughness problems with prior steels... you might try to find some S7 or S5. "S" is the Shock resistant Silicon steel family. I read somewhere that one of the "S" steels is used for jackhammer bits. So the "S" stuff is about as tough and impact resistant as industry has come up with I'm (educated) guessing.

Per Crucible, just as a reference point:

S7:

Code:

Temper     Charpy C-notch
Temp  HRC  ft-lbs
==================
 300   59  85 
 400   57  125 
 500   55  125 
 600   54  115 
 700   53  105 
 800   53  105 
 900   52  120 
1000   51  150

S5:

Code:

Temper     Charpy C-notch
Temp  HRC  ft-lbs
=====================
As Quenched HRC = 60-61 
 300 60-61 49 
 400 58-60 138 
 500 58-59 146 
 600 57-58 142 
 700 56-57 156 
 800 51-52  
 900 47-48  
1000 44-45

So, if you think Crucible's test data applies to knife blades at least somewhat, the sweet spot* for S7 looks to be Rc 56-57. And the sweetspot for S5 is Rc58-59 (but push it past 60 and toughness either falls off a cliff, or Crucible has a typo... looks like it might be a cliff, since S7 is also waaay down at the next hardness test point)

Based on those toughness metrics, I can't see why you'd bother with Bainite in S5 for regular sized (say up to 12") knives, but I suspect the answer to "why" is "swords". But maybe Jason call tell us what he knows about max hardness S5 in Bainite and what kind of benefits he believes he gets.

* assuming you think harder is better as long as toughness isn't compromised

Kevin R. Cashen · Oct 6, 2003

Originally posted by rdangerer
...(Somehow, I suspect you own a Rockwell tester also).
...

Yep! I'm a staggering boozer myself

I Use it regularly to zero in on how my electronically controlled salt baths are doing, I am not even above throwing samples under a microscope! In fact if being a scientifically inclined heretic makes you a lush I am a raging alcoholic!

If I am going to verify, or ignore, what may be in all of them egghead books, I want to be as thorough as I can. I have always found it hard to believe that industry has spent $$millions$$ on research and development under controlled conditions when all they had to do was ask the guy down the road dumping hot steel into goop in his garage

I am by no means a techno snob, and I do believe the you can make very good knives with the simplest of equipment, but you really need to know what you are doing to pull it off consistantly.

And I appreciate hearing the results also. They are relatively consistent with what Crucible lists for material properties. While I'm not surprised the actual numerical values are different (different test sample sizes), the relative magnitudes are in line between O1 and L6 Which is logical, just a bit contrary to what some other makers have suggested, something along the lines of "you can't look at Crucible's data... everything changes when it comes to a sample the thickness of a knife blade" or somesuch.

There are a few things that are indeed a little different in blade cross sections but I have found that many bladesmiths will latch on to this concept too tightly instead of trying to figure out why they are not getting the proper results. It all comes back to variables. The data sheet numbers were gathered under tightly controled conditions to assure their accuracy. If we get different results in a bladesmiths shop, where there are a thousand more things to go wrong, perhaps we should take that into account before we assume all the rules change with bladesmith magic.

I have heard a lot of steels badmouthed over the years by folks who just never nailed the proper heat treat for them.

Don't suppose you varied hardness and captured the impact toughness esults at various hardnesses? Yeah, I know, lots work... had to ask though.

Give me time

There will be a whole lot more broken steel aroudn my place in the future, and I will be happy to share my results, as long as folks don't mind having their world view messed with too badly.

Jason Arnold · Oct 7, 2003

rdangerer,

You hit the nail on the head. Just swords for the bainite thing. But the experimental swords I was (shop is closed down) working with were "composites", for lack of a better word. In other words, the edge was martensitic and the body was bainitic. The bainite has ranged in values, as (I have not completed testing), from 45 to 55. The edges were ideally 58/59HRC. Still pretty damn tough at 60HRC though. The edges will likely remain at 58/59, but I have not come to a final conclusion as far as the body hardness. Lots more testing still ahead.

Logically, I didn't see the point in using fully (or even composite) austempered S5 under a 12" blade. Was just overkill and since I FORGE S5, it would be making work for myself in the heat treating, instead of simply using a plenty adequate 10xx. You are right, full hard S5 works well enough for any size. But really its just for my big stuff and since I was trying to take impact resistance to a rediculous level, without "balancing the scales" in edge holding), I did the composite.

All this was without any doubt inspired by learning of Howard Clark's L6 stuff awhile back. Just wanted to see if I could do it too. Fun journey.

tallwingedgoat · Oct 7, 2003

Jason,

I might have ran into you at swordforum long ago. Where you the guy trying to make the indistructable sword with indistructable furniture? How are you putting a martensite edge on the banite body, flame hardening?

S5 banite sword is a cool concept that's teased my mind for sometime. But a bowie though, I think using already tough steel and doing the banite treatment is not terribly practical. I would opt for something with a lot of edgeholding potential like 52100, O6 and strengthen it.

Too bad its impractical to do that with stainless steel. You could really revolutionize the industry.

Jason Arnold · Oct 7, 2003

Wasn't me. I rarely do the full package anyway, mostly forge and grind blades bare.

I agree, an S5 b/m composite on a bowie would be overkill. But full hard and temper would be a great choice. I was thinking of making some full hard S5 bowies for the hell of it. Or at least the blades.

How are you putting a martensite edge on the banite body, flame hardening?

Fasting, praying to shinto dieties, ritual bathing and crossing my fingers while counting backwards standing on one leg and hopping. And beer for quench. Yep.

the possum · Oct 7, 2003

Yeah, I should mention, when I said I want to make a big Bowie, I do mean BIG. My current one is 24" long, but I'll probably bring the next one back down to 22" overall. It will be fully flat ground, with a convex edge, and 2" wide. To make such a blade light & quick, it will get fairly thin in cross section at the belly. That's why I want the extra toughness, just in case.

The numbers from S5 do peak my curiosity. Does anyone happen to have the charpy test values for L6? Or know a good site where I could find and compare them? Does anyone know of any sites showing the charpy values for several of these steels in Bainite?

Bad experiences from the past are due to poor steel choice, and in the case of my current Bowie, may be because this batch of 5160 really isn't quite 5160. It's behaving very strangely- not like Bainite should according to the heat treater. Though he was pretty confident he got all the temperatures right, because he also heat treated a 5160 machette for someone else in the same batch as mine, and it's performing perfectly.

rdangerer · Oct 7, 2003

Originally posted by the possum
I want to make a big Bowie, I do mean BIG. My current one is 24" long...

Uh, wow... Bowie. I'd call that a machete-ish or short-sword-ish blade.

Originally posted by the possum
Does anyone happen to have the charpy test values for L6? Or know a good site where I could find and compare them? Does anyone know of any sites showing the charpy values for several of these steels in Bainite?

The L6 toughness/Charpy figures are in one of my earlier posts in this thread... starts with words "Great question." The ft-lbs column is Charpy C-notch from Crucible, one good source of data:
Go here==> http://www.crucibleservice.com/index.cfm#
Choose "Selector" tab.
Then choose "Index".

Sources for toughness of Bainite structure... dunno. Would love to find such data myself.

Originally posted by the possum
Bad experiences from the past are due to poor steel choice, and in the case of my current Bowie, may be because this batch of 5160 really isn't quite 5160. It's behaving very strangely- not like Bainite should according to the heat treater. Though he was pretty confident he got all the temperatures right, because he also heat treated a 5160 machette for someone else in the same batch as mine, and it's performing perfectly.

What was the source of the steel? If it was old leaf springs, well, I wouldn't pench pennies here. Just isn't worth it. Buy the stock and invest in doing it right. Otherwise, you are guessing as to material (unless you pay for an analysis) and material quantity.

Jason Arnold · Oct 7, 2003

What was the source of the steel? If it was old leaf springs, well, I wouldn't pench pennies here. Just isn't worth it. Buy the stock and invest in doing it right. Otherwise, you are guessing as to material (unless you pay for an analysis) and material quantity.

I agree. Whom was the heat treater? If you don't mind me asking? Actually, you can just say if it was an industrial heat treater or a bladesmith offering a service. You might consider finding a metallurgical lab and sending it out to have some metallographic work performed. To tell you what percentage, what kind or even if you have a bainitic structure. I am not sure how much that will cost but it would be the best start to truly figuring out some reasons why your knife is not performing as expected. You may also consider a chemcial analysis of the knife, just to get that down pat. This all may be a little over the top, but you'd get some solid answers.

Or possum, maybe you just don't know your own strength?

the possum · Oct 7, 2003

rdangerer-

Lots of people have said the same thing. However, if I had access to a digicam, I'd post a picture of it. You could clearly see then that it is 100% Sheffield style Bowie, just bigger. Semi coffin handles, long sharpened false edge, classic Sheffield shape...

Sorry for not paying better attention. :footinmou But thanks again for the wonderful info. So... Am I reading those numbers right? L6 @ 56-58 Rc is 68 foot-pounds, almost twice as high as O-1. And S5 is 146 foot pounds at 58-59 Rc? So it can be a few points harder than L6, and still over TWICE as tough?! Wow. I did notice on Crucible's page that S5 has relatively little wear resistance, but then again I've never had one of my big Bowies get dull. I always have to sharpen them to remove nicks, chips, and other damage long before they become dull thru abrasive wear. So maybe I shouldn't worry about the wear resistance so much.

It's looking more and more like I may just have to make several Bowies. One from S5 fully hardened and tempered, and one from L6 Bainite! That could be an interesting comparison.

Jason-
I bought this barstock new from a leaf spring manufacturer in Kansas. It was supposed to be 5160. I hope he doesn't mind this, but Joe Walters of moonlit forge did the heat treating for me. If I'm not mistaken, fellow forumite Brian VanSpeybroek has also had some bainite blades heat treated by Joe, with excellent results. And, as mentioned, another 5160 blade he did in the same batch turned out great. After discussing this with him, we think maybe there was a problem with this steel. It was work hardening on me and doing all kinds of other weird things as I ground it. (I didn't know 5160 shouldn't do that, as this was my first experience with it) Even with very light swings, I've had problems with both chipping, *and* rolling. Last week, I was using light wrist cuts to clear some smartweed around the shed, and struck a nail imbedded in a hidden board. Me edge was ruined, but the nail wasn't even scratched!

Jason Arnold · Oct 7, 2003

Well, rolling alone under hard use wouldn't be too strange or all that bad. But, chipping, that seems uncharacteristic. For example, a hardened and tempered 1045 is near impossible to chip at 57/58HRC.

S5 seems to have been overlooked for years. It seemed like such a logical choice. But, that may be due to the fact that its hard to find in flat bar so stock removers have had to avoid it. And those who forge need to be equipped with precise HT equipment. No eyeball methods allowed. The anneal is especially necessary to have controlled ramping and temp holding.

Maybe Mr. Walters would be willing to simply re-do the HT? I mean you'd have to refinish it, but its a viable option.

the possum · Oct 7, 2003

Yes, I need to point out that Mr. Walters was VERY generous with offers to make things right. I've already sent him a couple small scraps from that bar of steel, and if he can work out a heat treatment for me, will redo the blade. Results are still pending.

I also would expect rolling before chipping, except it happened during very minor use. If it's already this bad, then I'm scared of what might happen if I ever REALLY whack something with it. (I end up striking hard objects on a regular basis. It can't be avoided)

So, I've learned about the great potential of two steels now. And neither one comes in decent sizes for stock removal guys!!

Jason Arnold · Oct 7, 2003

Well, if I'm ever lucky enough to get a power hammer or rolling machine, I'll offer it in flat bar for you guys. In the mean time, some smiths may be willing to do so.