Bainite Ht Services?

Michael J. Spangler

Michael J. Spangler

Joined
Oct 8, 2003
Messages
2,181
is there anyone out there hting bainite at a reasonable price right now?? i'd like to give it a try on a blade i'm making. thanks a lot guys
alright i changed this from ht services to procedure... i don't see a reason i couldn't fo it myself right?? or am i wrong?? Mete? Roger?
 
I would assume most heat treaters could treat your blade to bainite if you ask them to. Since it would require them to alter their regular routine, I would expect it to cost extra.

What steel are you looking to do the baininte HT on and if I may ask, WHY?

Jim Arbuckle
 
well i was looking for bainite just for the heck of it. i hear it could be done with O1 so i wanted to give it a try to see how much of a difference i could see. it may be beneficial to larger chopping blades, it may not be worth the trouble with O1
 
I gave it a go to turn 1095 into bainite for a slipjoint backspring. My backyard method was heat to critical, a quick dip in oil to drop the temp below pearlite formation, directly into a dutch oven filled with sand that had been sitting in a 500 F oven to preheat and directly back into the oven for 5 hours. Did I get bainie?? I don't really know. The hardness seemed to file about right and the spring works. I want to try this with a sword but that's down the road a bit yet.
 
OK here we go..... a new thought. should i be headed for bainite or for marquenching?
kevin cashen had posted a reply to a similar topic and stated that if toughness were his main focus he would form bainite but since edge retention is always a main focus on a knife he focuses on making tough martensite through marquenching.
he brought up a good point. like he usually does.
maybe he can chime in on this one. thanks for putting up with my rambling guys
 
There are some steels that are suitable for bainite and there are some that are not .You have to check the TTT diagram. The only accurate way to do it is with molten salt. For a particular steel bainite will be a bit softer but a bit tougher than martensite. So if the application is impact you might choose bainite . Marquenching gives you martensite nothing else.
 
Almost any of the steels that we work with can make bainite, just some are easier to do it with than others (e.g. L6 will do it with little effort while one may have to get creative with 1095). Oil hardening steel (what I would refer to as deep hardening) works best because in order to efficiently stop and hold above Ms one will be using a slower quenching medium. The kicker that most folks aren’t aware of will become apparent if you have a look at those TTT curves that mete recommends. In order to approximate knife hardness from bainite you need to form the lowest temp lower bainite. If you look at the scale on the bottom of the curve you will notice that it is logarithmic….
At around 800F upper bainite will start to form in moments, but at 500F. and below (where you need to be) processes are so slow that it may take hours to complete the bainite transformation, if you rush it all you will do is make martensite as soon as you cool just a bit . So you need to cool very fast to avoid any other transformations and then stop things dead around 500F to 450F (depending on the alloy) and then hold there for many hours.

It is a lot of effort when, in my opinion, most of the real need for bainite in knifemaking is for marketing. You know- hype like touching tip to tang, hacking up masonry objects and standing on a knife blade while it is still imbedded in the 3/8” steel plate that you drove it through, things quite honestly that have nothing to do with actual knife use.

Recently at my shop I handed Ric Furrer a 1cm x 1cm x 3” piece of L6 with a slight kink in it, it was fully martensitic via martempering and tempered to around 55.5 HRC. It had bounced the maximum 240ft lb. load of my tester so effectively that I won’t do it that way again for fear of my tester! As we both shook our heads I asked “who needs bainite?”

In the process of plummeting a blade down in temperature while it is undergoing the unbelievable stress of forming martensite, causes all kinds of things to occur inside that have the potential for disaster then or later on. My love of martempering/marquenching comes from its ability to accomplish, through gentle cooling and autotempering effects, this in a way that reduces much of that potential.

With proper heat treating of a good alloy one can so far exceed the reasonable use of any knife that it renders all of this “super tough knife” hype irrelevant, (once again, in my opinion). Some say that one may be able to get decent edge holding with bainite, I say that it is a certainty that we can get excellent edge holding with martensite and meet any toughness requirement for a knife. A knife that can cut all day but may fail as a prybar or hammer is still a good knife, a prybar or hammer shaped like a knife falls short in any of those uses. For me it is simple, what is the primary function of a knife? Which heat treatment addresses that function the best?

Much of the bainite hullabaloo, is the same as much of the chest thumping about superior forged blades and esoteric heat treatments, most of the extra performance is in areas that have nothing to do with cutting things- it is something to think about. ;)
 
geez after two year of the ashokan seminar and reading your posts and articles online i can finally follow something you wrote and undertsnad what you mean.
man i love this metalurgy
so then marquenching it is. i figured, just wanted a little info to back it up.

theres no need to form bainite in scalpels right?:rolleyes: :p

application application application

thanks for the quick and information reply. can you refer me to anyone who can heat treat the blade for me? untill i find a bag of cash somewhere i won't be able to get a salt bath set up soon enough. thanks
 
Hey there, Kevin. Thanks for chiming in here with such great info. Stuff like this is why I've become so interested in using L6 on some future projects. (got your email, by the way.)

Hope ya don't mind, but I have a few honest questions on this subject. I find myself asking the same ones over and over again, because I just don't make enough knives to really test things out for myself.

Kevin R. Cashen said:
It is a lot of effort when, in my opinion, most of the real need for bainite in knifemaking is for marketing. You know- hype like... hacking up masonry objects and standing on a knife blade while it is still imbedded in the 3/8” steel plate that you drove it through, things quite honestly that have nothing to do with actual knife use.... With proper heat treating of a good alloy one can so far exceed the reasonable use of any knife that it renders all of this “super tough knife” hype irrelevant, (once again, in my opinion).
Click to expand...

I can certainly understand where you're coming from with this. But, what happens when serious abuse like this is what the blade needs to handle? Not being facetious or doing some mall-ninja posturing there, really. A few common jobs on the farm where it would be nice to have a "super tough knife", are: chopping roots on trees that we mostly pull out with a tractor, chopping/cutting the mass of baling twine off the back of the manure spreader, and the worst one is cleaing weeds by hand from around the buildings. It's practically gauranteed that you'll strike a piece of hidden scrap iron or a concrete foundation while doing that. We butcher quite often, and I do use a meat cleaver for certain portions. Leg bones are every bit as damaging as the things mentioned previously. (at least from what I've seen.)

I've mentioned another specific use for my big bowie many times in the past, where accidental impacts with concrete and steel are simply unavoidable. These hard substances are of course not its primary target, but unfortunately, reality dictates that those will be the limiting factor to my blade's performance. Is that "reasonable use"? Probably not. But right or wrong, that's how I use my knife, and I've had to sharpen over 1/4" of steel off its edge in a one year period because of the damage. My last knife broke. The knife before that was retired from use after I ground off a large amount of metal, and kept getting damage.


Kevin R. Cashen said:
For me it is simple, what is the primary function of a knife? Which heat treatment addresses that function the best?
Click to expand...

Well, that's what I'd like to know. What is the best treatment for a knife that has never gotten dull before needing serious sharpening to repair damage? What if the limiting factors (regardless of "primary function") are indeed above and beyond "normal use"? I'm honestly not trying to pin you down here, and I'm not trying to play devil's advocate for the bainite side. I'd just really like to know before I invest a huge amount of time in another big blade. "Who needs bainite?" I don't know. Do I? I'd like to think it never hurts to look for something better, though of course I don't know if it's even possible to get better, and am willing to accept that.

What are your thoughts?
Please feel free to respond via email if you'd rather not go into it here.
 
If nobody minds, I'd like to throw in a question too...

Would bainite in the top of a differentially hardened chisel or punch be less susceptible to "mushrooming?"
 
Thingmaker - no......Possum , what was your last knife made of ? For your uses a knife will wear out eventually no matter what. L-6 or CPM 3V would be my choices.
 
Bainite would probably not mushroom, it most likely would split off. Typically you want the end you hit with the hammer softer than the face of the hammer.

I about lost an eye as a child by trying to drive a claw hammer under a large nail, using a ball peen hammper. The ball peen hammer face chipped and stuck in the tear duct of my right eye. Just a little close!

Jim Arbuckle
 
possum: i know i'm not a pro but i think no matter how tough a steel is going against hidden scrap steel and chunks of concrete would chip it no matter what, as far as chopping bones and going through huge roots and such maybe you should just look a little into edge geometry, if the chopping is the main function of a knife you shouldn't need a tall hollow grind to a zero edge... that leaves nothing but a thin little easily sharpened blade with no backing, like a straight razor, bot on the other hand a lot fo the clevers i've seen have a thick slack belt grind on them, that can take the abuse a little better, though having said this, the grind height, stock thickness, and final edge thickness all play into the geometry of the blade.
a 1/6" thick blade ground on an 8" wheel 3/8" high with a final edge thickness of .005" is a pretty fine little blade not suitable for much but opening letters
but a 1/4" thick blade grond on an 8" wheel 3/8" high having the same final edge thickness is going to have a beefier backing right?
someone chime in if i'm wrong here. i hope this helped
is short, re think the steel for the application and the geometry of the blade
i'm with mete on this one. L6 or 3V, i've also heard some good stuff about the S serries steels, but i havent worked with them myself.
 
the possum said:
Hey there, Kevin. Thanks for chiming in here with such great info. Stuff like this is why I've become so interested in using L6 on some future projects. (got your email, by the way.)

Hope ya don't mind, but I have a few honest questions on this ...

What are your thoughts?
Please feel free to respond via email if you'd rather not go into it here.
Click to expand...

I think I remember your concerns for the bowie that may have accidental contact with things other than the primary target. Some folks got touchy, but I personally got a chuckle ;) (I have used a .357 for the same task, so much for matching the tool to the job:rolleyes: ).

No need to worry about offending me with taking an opposing stance in matters that involve ones personal tastes. I find it refreshing to be able to discuss something that both can disagree upon and yet nobody is wrong, for once. I am only a crotchety old curmudgeon (was it curmudgeon, mete?) when, as a friend of mine says, “somebody whizzes on my head and tells me it is raining”. When a person ignores facts and then expects me to do the same, I can get very undiplomatic. It is one of the reasons my friends carefully filter political comments around me, in these days when facts no longer matter in our culture:grumpy: .

I may have a hard time giving you advice since it is beyond my experience, to have a knife that had to do these things, although I have more than a few beaters setting around. Even if I don’t give a rip about the blade, getting the job done in the most efficient manner still takes priority with me. I move trees all the time myself, and for roots, filled with dirt and rocks, a grub axe, pick or old hatchet gets the job done in one pop, through dirt and all. The steel is not the best on these, and I don’t even know if they have been heat treated, but they are ground with a bevel designed to do this work.

It has been a long time since I had to mess with the paddles in the back of a spreader, I mostly wanted a tool that could get the rocks out of the soupy #@@$ so my hand didn’t have to rut them out when the paddles started hitting them:barf: . I did have a problem with weeds around the roto-tiller tines so I made a reversed hooked blade device designed to do that task, ( still had to stop and get wire cutters whenever I found some wire in the mess though).

I have to clear out weeds from my scrap pile and along foundations as well, I have an old machete that does some of the work but it is very inefficient at getting any of the weeds around metal or concrete even if I say the heck with it and try to cut through those obstacles. The fish line on my weed whacker does the job in 1/10 of the time, with no damage to the tool or the foundation, and costs 1/100 of even my cheapest commercial blades, a lot easier on my back as well.

Butchers have the same concepts, there are knives for boning and slicing and then there are heavy blades like cleavers for whacking, and the edge geometry will be suited for the task. If a cleaver failed to defeat bone, I would doubt its manufacture or design, but then butchers also have saws.

Sometimes we just have to admit that we need more than one tool, although just one appliance would be nice, you can’t cook dinner in the sink and you can’t wash dishes in the oven (you could give it a whirl and answer to the wife afterwards, but I rather take my chances with exploding blades:eek: ). At least that is my opinion on the matter, but my philosophy is guided by making the best knife that I can, if a person wants to use it as a pipe wrench I will have to compromise that principle, so I tend to reject the concept.


Even bainite cannot overcome basic physics, i.e. concrete or stone will have a higher Rockwell than steel, thus no matter what you do, the stone will probably win. Stone cutting tools are made different and work entirely different than knives. If I were in your position, and still wanted to use a knife to do these things, I would get a good supply of the cheapest blades I could find and chuck one and grab another when I needed to:) .
 
Thanks for responding, guys, and Kevin especially. I respect all of your opinions. Glad I didn't rile you up over this, as that's not my intention.

We end up using axes, machetes, and grub hoes for a lot of those tasks ourselves around the farm; I guess I really only offered them all as examples that sometimes things don't go as planned. String trimmers are of little use against 2" thick Giant Ragweeds, though. :)
I specifically mentioned the butchering thing, because deer leg bones have damaged my edge every bit as bad as the concrete. Thus I'm sometimes left scratching my head when I read about disdain for the whole concrete thing from someone who makes swords.

I think I remember your concerns for the bowie that may have accidental contact with things other than the primary target. Some folks got touchy, but I personally got a chuckle (I have used a .357 for the same task, so much for matching the tool to the job ).
Click to expand...
:D Yeah, a .45 or 12 gauge is my primary, but there's places where I simply can't risk shooting. The bowie is more exciting, anyway. :)
This situation is really the whole reason for all my pondering and fretting. If I designed a blade for only the primary targets, I could get by with Pakistani steel. If I designed a blade for only the toughest things I'd hit, (the concrete and steel) it would be way too blunt to work for the other stuff. I'm approaching the situation by making the edge thin enough to do well on the soft targets, yet trying to find a steel strong and tough enough to resist damage from the hard ones.


For your uses a knife will wear out eventually no matter what.
Click to expand...
I would get a good supply of the cheapest blades I could find and chuck one and grab another when I needed to :).
Click to expand...
Yeah, I know. Just hoping to make it last an extra year or so before I have to make another one. I've tried the cheap blade thing, and besides being wholly unsuited to the task, (because of balance, ergonomic, & other issues,) it's not suited to my philosophy. Like Kevin said, "my philosophy is guided by making the best knife that I can." I'm still on the search for that mythical "ultimate" knife. I plan to try martensitic L6, and see if I get any closer to my goal.

Thanks for the great discussion, everyone. Hope it ain't over yet.
 
A deers leg bone is seven times the density of a cows !! Not surprizing since the do so much jumping around ! I too have multiple tools , an old already chipped axe for digging out roots and of course a trusty mattock .Kukri, shears, saws etc. ...Yes I am a certified curmudgeon ,I don't care what anyone else does or thinks about me , I live a "parallel reality ".
 
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