Testing blade performance

Chuck and Rick: thank you for the kind words. You mentioned that you did not get nice quench lines when you heated and quenched the whole blade, then I figure you tried the differential temper. You did not get real etch results because there were no great reads available. It is the old garbage in garbage out syndrome. You cannot achieve the dynamic grain structure with the differential temper. The dynamics of the differential hardening go a long ways beyond what is available by differential tempering a fully hardened blade. When you etch every blade, this kind of learning is obvious. After you get some experience behind you, etch and compare a blade that has been fully hardened, then differntially tempered to a blade that has been differentially hardened. The results will be immediate and obvious.

If you chose to make 'art' blades these events do not matter. If high performace is your goal, everything matters.
 
OK, I believe I had a light turn on! All this talk of Martesitic cones, etching patterns and differential hardening as opposed to differential tempering is making me think... (Can be dangerous)

If I differentially harden a blade I get a Martensitic cone in the cross section of my blade. I'm not sure what the structure above and to the sided of the cone would be called but it's probably pearlite or bainite or a combination of softer/springier structures. A combination of these softer/springier structures, the martensitic cone, the blade geometry and a proper tempering cycle(s) gives the blade is strength/ability to forgive bending yet have a servicable edge. If I differentially harden a blade to give it the martensitic cone and then differentially temper the blade, their would be some sort of destruction of the internal cone as the heat that is being applied to the spine of the blade would esentially be growing a cone of a different structure down into the martensitic cone? This seems like it would give all sorts of funny looking etch results and at the same time reduce it's strength.

If I take a fully quenched blade and differentially temper the blade, there would be no internal Martensitic cone, but rather a gradual uncontrolled blending of the softer structures with the martensite. This would give no definite etching patterns and a less controlled toughness/hardness combination?

So, it seems like the ideal situation is to differentially harden the blade to create the cone and then fully temper to control the softer structures and at the same time control and maintain the cone?

Please excuse my ignorance, I'm probably way off base. I'm just a hungry new guy trying to make sense of it all. Seems like the more I learn, the more I need to learn. So far it seems like the key to a high performance knife is to control as many if not every aspect of it's creation.

CONTROL

I'll shut up for now,
Rick
 
Hello Rick. By jove I believe you got it!

There is no need to differentially temper the differentially hardened blade as the top never gets hard unless you are really sloppy in heat treat. You temper the whole blade, with little influence to the top cause it doesn't need it. the temper is for the benefit of the hard, martensitic portion. Check for chip and then enjoy.

The first time I saw the cone, I started asking questions, there aren't a lot of answers cause industry who fronts most of the research doesn't work with differential hardening. I strongly believe the nature of the cone, its influence on the surrounding matrix has the potential to take knives further than they have ever been before.

Good job Rick!
 
Thanks Ed! Thank you sooo much for all of the knowledge that you have shared with all of us. Last night I sat down to re-read some of your book, and I realized that I have a problem. I think it's a big problem. I don't owne an acetylene outfit, therefore, I can't "paint" the heat on just the edge of the blade for quenching. After all that you have taught us about the cone, I can't help but think that heating the entire blade for an edge quench will have a marked difference on the cone between an edge heated blade and mine that would be (for now) fully heated. I'm thinking that I could still have decent results but I would have to play with the speed of the quench and the depth of the quench to get similar results to a blade that had only the edge heated prior to quench. Is that correct? Any suggestions?

Rick
 
All events contribute, each its own piece of the pie. Most important, quench on a rising heat, as soon as nonmagnetic. Non-magnetic will remain below the point where the blade will harden, so it is important to be right on. This comes iwth practice. Heat too hogh and you get a different knid of martensite that does not contribute to cut and tough as well as the lower temp stuff.

An oxy-acet out is good to have as soon as you can afford it. Practice your heating techniques until you get it right. You will continue to learn as long as you make knives. It doesn't come all at once, at least for me it took a lot of quenches to get it where I figure it is right. I 'hardened' a blade of mild steel hundreds of times while learning on 5160 blades. Just like artists in othere venues you have to practice and evaluate your porgress all the time.

There are many who will tell you you are wasting your time, the experimental method will provide the most realistic evaluation. Don't let the theory guys get to you, like the Wright Brothers they refused to believe man could never fly. More on this later if you want to take the time to read.
 
What Rick said! Yes Thanks Ed for sharing your wealth of knowledge with us newbies! I am also in the same boat as Rick, got no torch and I heat the entire blade in the forge and edge quench and then do a regular temper on the whole blade. Heres a quench oil question too. If everyone is having trouble finding Quenchtex A, is the a decent equivalent that is easier to get? I did a search for quench oil and came up with Chevron quench 70, Texaco Canopus 100 & 150, and Chevron utility oil 100 in either high or low viscosity, all of which were listed as quench oil in the product data sheets. Would any of these be a good replacement for the quenchtex A?

Chuck
 
Hello Cuck; Request to see the data sheets for the quench oil, get the one that comes as close as possible to the Texaco Type A. They all have astm specifications and I would suspect it is the higher viscosity oil that you want.

Talking about torches. I as usual this time of year I spent the day in my shop. I tried to visualise what it would be like working without my oxy acet set up. I would not be without it. You can get along without an arc welder, but not the torch. Watch the used section of you paper, here in Riverton there are several sets that come up for sale several times a year. Go to a welding oufit and get them to give you their pitch, find out who makes quality ones and watch for your opportunity. I have a very old Victor acetelene gauge and an off brand oxygen gauge. I cuss the oxygen gauge but love the Victor. They can be rebuilt.
 
Ed, Thanks for the tip regarding the torch brands. I did a little research today. Everybody recommended the Victor brand also, second place was Harris and it was unanimous to stay away from the off brand equipment! I called several pawn shops, they sound promising. Too bad my wife already bought my Christmas gifts. Maybe Santa will leave me a little surprise;)

In your earlier reply you said to "quench on a rising heat". Does this mean that I should watch my heat very closely and quench as soon as I get to critical and not let it stay at critical for very long or climb above it?

By the way, nobody is going to convince me that I can't do it!

Rick
 
Rick: As soon as you reach nonmagnetic, even out the heat and quench. A little above is OK, a little below and nothing happens. A lot above is a wreck.

Yes you can do it!
 
Rick,

congratulations on the load shaft score. I have never forged any O-1 so I can't give you any advise in that area. As for Parowan; when I was kid I lived in Preston and kept hearing about how great Beaver was and I don't mean the critter with long teeth, any way when I finally got into Beaver It didn't seem so great so I went on down to Parowan just for fun.:D Actually I helped out a friend of mine who was doing some crop dusting down there.

Back to the 5160 there seems to be some performance gains in using a continuous quench. By this I mean quench in oil, then at 100 degrees or so remove from the oil and quench in cold water from the water dry the blade and put it on some dry ice when the blade has had time to get as cold as the dry ice then put it in some liquid nitrogen let it soak long enough for the temp to stabilize then remove and bury in ashes or vermiculite so that it will warm up slowly to room temp do this three times and then temper.

I have done this a couple of times and have gotten two hundred cuts out of 5160 but would like to do some more test when time permits. I don't feel that I have explored this enough to say that this continuous quench is an important part of making a knife from 5160 however. More tests may show conclusive evedense to prove or disprove what I have done so far.
 
Hi Bill, I've had the exact same experience with Beaver:( ... Only I headed further south to play golf in St. George :p

It's funny that you mentioned the continuous quench. I was day dreaming at work the other day, and I had an idea to do something very similar. I had read on the web about some of these cryogenic companies that bring the temp down really gradually to -320 and then soak it for a period of time and bring it back up to room temp in the same gradual way. I thought that I would quench the blade, temper it, then do my own gradual sub zero quench by first putting the blade in dry ice and acetone then from there to the liquid nitrogen but up in the vapors if colder than the dry ice, then into the dry ice and then reverse the process all taking about 24 hours.

I have a couple of questions for you cryogenic guys. Where do you get the liquid nitrogen? Is it expensive? Would I have to have my own tank to keep it in? Any other advise would be appreciated.


OK, So now I need to get some time to actually forge something!

Rick
 
Rick,

I can get you a five gallon bucket of the chevron quenching oil that I use for about fifty bucks and shipping. I,m not sure what the shipping costs would be but at this price it might be cheaper to get a fifty five gallon drum of the stuff.
 
Hallo Fellas!

I am on a vacation in MD right now...and a lot of you are at the Blade show. I found this thread while browsing....Glad I did.

Ed is the man who got me where I am...and keeps me going by constantly raising the bar. I know that is true for all of us.

I have forged those load shafts...and proved Ed's oft spoken words.
So I could take the next step in the performance ladder, I had to purchase a barrel of TYPE A. (Another on the way!)

If you need the best quench oil available, let me know and we can discuss the brass tacks.

shane
 
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