8Cr13MoV

S

sorak34

Joined
Jul 12, 2010
Messages
3
Are blades made from 8Cr13MoV able to get a hair splitting edge, or is a utility edge the best i will get. and if so what is the best way to get that keen edge.
 
Yes you can, but you need to be gentle when sharpening. That steel is very soft when it comes to sharpening, so removing the burr is often difficult. Let the knives weight do the work when removing the burr. What do you use to sharpen?
 
yeah it is very possible to get a hair splitting scary sharp edge

how long it can keep it is another story

but yeah i agree, just be real gentle because the steel is softer than "premium" steels

but it works very well
 
Ok, I have a Persistence and this got my interests. By soft, I know there is a hardness scale. But in real life application, what does this mean? DOes it mean that say for general office and home use (not using it to garden or camp or boat, but opening boxes, cutting twist ties, opening letters, and those pesky sealed plastics in the Walmart purchases), you would have to resharpen it after say 3 uses versus 10 uses if it was D2 or something else that a Delica would have?
 
The steel is certainly no 'soft' in terms of Rockwell hardness. Byrd knives have fairly consistently been reported at testing at 61. Wear resistance has nothing to do with hardness either. It is probably more an issue of ductility and malleability. Perhaps the burr doesn't pop off quickly because the steel doesn't fracture as readily as others.
 
I've had similar experiences, I've also found 8cr to be very easy to sharpen and to get just as sharp as my other steels, it just won't hold it as long as those were of course.
 
By soft i meant the steel is mailiable in a sense. If you've ever sharpened ZDP-189 and then 8cr you can "feel" a difference in softness. it's kind of like the difference between rubbing solder on something hard and rubbing a hammer on something hard. You can just feel it through the stone i guess. Hard to explain. But also by soft i mean that you can tweak the edge easier, so it has less resistance than a harder steel. if someone can explain it better feel free lol.
 
The one knife made out of that steel that I sharpened got hair popping sharp, with little work. It wouldn't hold an edge, but it was easy to sharpen.
 
Well i have never been successful with with whetstones, so i bought Lansky's system, no success the angle dont match my blade, so now i mainly use a pull-through sharpener and files.
 
Pull through sharpeners screw up an edge up horribly. you would be better to just not sharpen it. Buy a spyderco sharpmaker, you can get awesome results with little to no effort and when you get a feel for the angles you can do more. Never use a file on a knife unless it's the particle ones specifically for knives. If you want to try the lansky again, use a 15 degree per side, or 30 overall, i don't know how those work exactly. that should do you good.
 
Is there any limitations on what this steel cuts vs. say some other steel? I was trying to cut up a credit card tonight with my Persistence, and it was not cutting it. I got scissors and they worked much better. Is that a sign of the thinness of a blade, or the "hardness/softness" of the steel, or a sign of its sharpness? Or nothing to do with any of that?
 
edge finish, to cut up a credit card you need to slice with a rough edge, push cut with a polished edge, or just waste a lot of energy with something in between.
 
Buying knives made from some copycat Chinese steel is not the way to get good performance.


Like I always say, edge geometry and heat treatment are just as important as metallurgy.


Buy a knife from a trusted maker and it will perform. :thumbup: :cool: :thumbup:


Buy a knife that is designed to make money for it's Chinese maker is likely to get you only what you paid for,

...i.e., a cheap POS. :eek:



Don't overlook things like triple tempers and cryo treatments if you what a high performance knife steel.






Big Mike
 
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LawyerSam said:
Is there any limitations on what this steel cuts vs. say some other steel? I was trying to cut up a credit card tonight with my Persistence, and it was not cutting it. I got scissors and they worked much better. Is that a sign of the thinness of a blade, or the "hardness/softness" of the steel, or a sign of its sharpness? Or nothing to do with any of that?
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Softer steel has a great characteristic for work. If you hit something with it or fold the edge or something, it's easy to realign or sharpen out. The reason being the harder the steel more often than not, it will chip, leaving a void in the blade. Think of a piece of paper. Hard steel would be like cutting a piece of out of it, as in a chip. Where as softer steel folds, so it would be similar to leaving the piece of paper intact and just smooshing the bottom a bit. Cutting ability has a lot to do with sharpness, the type of grind and edge geometry. An axe is a wedge, designed more for splitting than cutting, where as a razor blade is thin and acute, more for cutting. That persistence is no slouch. It's not the best steel on the market, but that steel takes a wicked edge and cuts nice. Rust proof practically too. Get a sharpmaker and just touch it up before you put it away after a long day of cutting, it'll last a long while.
 
hardheart said:
The steel is certainly no 'soft' in terms of Rockwell hardness. Byrd knives have fairly consistently been reported at testing at 61. Wear resistance has nothing to do with hardness either. It is probably more an issue of ductility and malleability. Perhaps the burr doesn't pop off quickly because the steel doesn't fracture as readily as others.
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Sorry to correct you hardheart, but wear resistance is directly related to hardness. Hardness is the number one contributor to wear resistance, followed by the addition of certain alloys which primarally allow steel to be quenched slowly (retain a high hardness while not cracking) but can also cause desired micro stresses in the crystalline structure of the steel and prevent deformation on a micro scale. For the most part, the harder a steel is, the less likely it is to move due to stress (dulling). If a blade is overhardened (under tempered), it will chip which the result of too much stress remaining in the structure after heat treat which allows light pressure to cause cracks. Ductility is that ability to plastically deform without fracture in tension and malleability is the same property but in compression.

Think of the difference between aluminum (very soft) and diamond (very hard). We sharpen our blades on tiny diamonds simply because they are so hard that they can hold their edges when rubbed against hardened steel. The harder the material, the better the edge holding.

I have a very hard time believing that some 8Cr13MoV blades are measuring 61 Rc and are in any kind of usable condition. That would require a very fast quench and a very light temper and simple steels like this don't too well to that kind of heat treatment. Because it has .8% carbon and only 13% chromium (minimum to be considered stainless) it is very likely that some of that chromium will form chromium carbides with some of the carbon and bring down the amount of carbon that is available to harden the steel. This will also cause the steel to fall below the "stainless" level because it lacks 13% free chromium.

To the OP: 8Cr13MoV is a very simple steel, but in my expirience it can take a nice edge that tends to dent instead of chip. Sharpening is easy and I enjoy sharpening 8Cr13MoV because of how quickly I can get it sharp with diamonds and a white (fine) ceramic benchstone. As long as the 8Cr13MoV is heat treated right (which it has been in my 3 or 4 knives that use it) it will perform great and take a keen edge if you are willing to work at the technique. After you are sure you have fully sharpened both sides of the edge (they meet at a single point) try a few very light passes on your fine stone on each side with the edge held a 10 degree higher angle than you have been sharpening at. I find this takes off even the nastiest burrs without damaging the fine edge you've work hard to produce.
 
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Ive carried a knive most of my adult life, but was not untill recently that i became curious about how a knife is made, the type of steel that goes into a knife. Any time i had a question i was always brought to this forum, so i joined, and now i am truly glad i did. Thank you for your time SuzukiGS750EZ.
 
Sure it gets hairsplitting sharp. My tenacious, persistence, crossbill, and crow are all hairsplitting sharp. As for edge retention, it is entirely adequate for my purposes since I don't cut a lot of abrasive or hard material. I only use it for light and medium EDC tasks like food chores away from the house and package and letter opening duties.
 
sorak34 said:
Ive carried a knive most of my adult life, but was not untill recently that i became curious about how a knife is made, the type of steel that goes into a knife. Any time i had a question i was always brought to this forum, so i joined, and now i am truly glad i did. Thank you for your time SuzukiGS750EZ.
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No problem :-) I enjoy helping other people and passing the knowledge on.
 
michaelmcgo said:
Sorry to correct you hardheart, but wear resistance is directly related to hardness.
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y'know, I misspoke. Increased hardness does increase wear resistance, and I have tons of data sheets backing that up. It was a horribly worded statement, and what I had in mind when I was typing were alloys like S60V, or stellite. S60V isn't usable for general purpose knives above 56-57, while having very high wear resistance relative to many other alloys at greater hardness, and stellite and similar (talonite, dendritic cobalt) have highly wear resistant components while not even being hardened like steel does. I guess I just mean that the reading on the Rockwell C scale is not the only component to wear resistance, you can have a very high carbide fraction also provide it. It's a reason why some steels are not seen as often on custom knives. Even when fully annealed, the amount of carbide makes it difficult to grind and increases the expenses of time, grinding belts, files, etc.

http://www.spyderco.com/forums/showpost.php?p=140419&postcount=12 Sal has repeated this, and I can't find the post, but someone had their Byrds tested independently and confirmed.

Perhaps the austenizing temp is on the high end to increase the Cr in the austenite and maintain corrosion resistance. AEB-L has 12.8% Cr and is still stainless, since it has only 0.65% C.
 
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