Some steels, like VG-10, are more prone to rolling and some like S30V are more prone to chipping when hitting something hard -- say, cutting a steak on your plate and having the edge hit the underlying ceramic too hard.
It'd be nice to see a list of how each steel Spyderco uses or used to use behaves. H1 (Roll/flatten), ZDP-189 (Chip?), 8CR13MoV (Roll), ATS-34/154CM, ATS-55, S90V, CPM-D2 (Chip?), CPM-M4, GIN-1 (Roll), etc... anybody with wider experience than me, feel free to chip in.
Also, does how the steel is made have a difference? For example, do powdered metal steels have a better chance of chipping because of the sintering causing weakness versus molten traditionally made metal?
Steels: Chipping vs. rolling
Steels: Chipping vs. rolling
Newest :spyder: in hand: Halloween Handle Hap40 Endura and Delica.
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delicafreak
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chode messiah
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I've found 8Cr13MoV tends to flatten, but not a whole lot. Only real damage I've had was when a [former] friend though it would be cool to whack the edge against the edge of a hatchet he found. Chipped it a tiny bit near the tip of the blade, but after repeated sharpening it's no longer visible. H1 flattens/rolls slightly for me, but only under heavy use (and with thinner profiled edge)
I don't feel I have enough experience with the other steels to weigh in, as I usually only edc a Tenacious due to its ease of sharpening and super low price point. If I'm going into a wet/marine environment, one of my Salts comes along instead. The other steels get some use; generally the higher end knives get edc'd for a few days then retired (sometimes they get brought out for a special function or just to spice up the rotation). When I have more play money for knives I think I'll start carrying higher end models more often.
I don't feel I have enough experience with the other steels to weigh in, as I usually only edc a Tenacious due to its ease of sharpening and super low price point. If I'm going into a wet/marine environment, one of my Salts comes along instead. The other steels get some use; generally the higher end knives get edc'd for a few days then retired (sometimes they get brought out for a special function or just to spice up the rotation). When I have more play money for knives I think I'll start carrying higher end models more often.
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The Mentaculous
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Gin-1 always rolls in my experience. ZDP does chip, but it takes a lot of force, as it is very strong. 8cr13mov rolls/flattens in my experience.
I don't think powder metallurgy effects the toughness characteristics, but if it does I'd assume it'd improve them. It does increase strength in pretty much all cases I believe over traditional smelting processes.
I don't think powder metallurgy effects the toughness characteristics, but if it does I'd assume it'd improve them. It does increase strength in pretty much all cases I believe over traditional smelting processes.
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hunterseeker5
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The purpose of powdered metallurgy is to assure more uniform distribution of elements within the metal. This allows for more uniform composition, smaller carbides, and a higher achievable hardness while maintaining toughness. You could say that a major improvement of the powdered process is to improve toughness at a given hardness.I don't think powder metallurgy effects the toughness characteristics, but if it does I'd assume it'd improve them. It does increase strength in pretty much all cases I believe over traditional smelting processes.
I have never had a knife blade chip, but I don't use hard steel blades on metal. You can take a Stanley wood chisel and chop through wood into concrete - and get chipping. A harder steel will also chip out on concrete.
I have never had any blade chip using 440C, D2, M2, 154cm, ATS34, VG10, or ZDP-189. I don't normally get chipping with any blade - if I am careful about use.
I wouldn't be surprised if you get chipping if you chop with a knife on very hard wood knots and the blade is ground very thin. That is why axes are generally softer steel with convex grinds.
I have never had any blade chip using 440C, D2, M2, 154cm, ATS34, VG10, or ZDP-189. I don't normally get chipping with any blade - if I am careful about use.
I wouldn't be surprised if you get chipping if you chop with a knife on very hard wood knots and the blade is ground very thin. That is why axes are generally softer steel with convex grinds.
Learn to sharpen right, and none of this matters...
Far better is it to dare mighty things, to win glorious triumphs, even though checkered by failure... than to rank with those poor spirits who neither enjoy nor suffer much, because they live in a gray twilight that knows not victory nor defeat.
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Phil Wilson
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Youzer,
Chipping and rolling are mechanical properties of the particular steel you are using. All tool steels have a stress limit before failure. Stress is the force applied divided by the area resisting the force. If you have a very high force and a very small area like on the edge of a knife that is cutting a hard material the stress limit can be exceeded very quickly and you have failure. The failure can be rolling, denting or chipping depending on how much force is applied. A blade at a fine edge will bend back and forth during cutting. If it bends without permanent deformation then it is in the elastic range. It is acting like a spring. If the elastic limit is exceeded then it is “bent” or permanently deformed. You see that as rolling on an edge. If the force continues then it will finialy break “chip”. This is all a function of the hardness or strength and varies with different materials. Mild steel for example can be bent back on itself without breaking. It is soft and is working in the plastic range. You can’t do that with a file. Very hard materials have an elastic range and a very narrow plastic range. They are said to be brittle. The more alloy that is put into a knife steel at a given hardness will tend to narrow the plastic range. This is also a function of the hardness. Very high hardness blades have a narrow plastic range and will flex some, bend just a little and then break. You mentioned several knife blade steel grades. All have different mechanical charteristics and the challenge is to understand how the material acts, heat treat and grind to get the best balance of properties. A fine grain like you find in the particle steels will tend to be less brittle than a more course grain wrought base steel. If you want a blade that will fail by rolling at the edge then it will need a softer heat treat. If you want a very strong edge that will stand there, and hold the carbides in place for maximum wear then it has to be harder or stronger. For example look at CPM S90V. A fine grain base so it is inherently strong but full of alloy, so that tends to offset the ductility. Heat treat it hard (RC 60 +) so it will not bend at the edge and hold the hard vanadium carbides in place to resist wear and you have a very wear resistant edge. Push it too hard during use and if the edge is too thin, not enough material to offset the stress and you have a breaking type failure (chipping). In addition to all this dynamic forces like chopping increase the felt force at the edge very quickly. So you have to choose the steel for the application, decide what qualities you want and heat treat and grind the edge to meet all those specifications. It’s all a fine balance and Spydeco does on **** of a job to meet all these requirement IMHO. Phil
Chipping and rolling are mechanical properties of the particular steel you are using. All tool steels have a stress limit before failure. Stress is the force applied divided by the area resisting the force. If you have a very high force and a very small area like on the edge of a knife that is cutting a hard material the stress limit can be exceeded very quickly and you have failure. The failure can be rolling, denting or chipping depending on how much force is applied. A blade at a fine edge will bend back and forth during cutting. If it bends without permanent deformation then it is in the elastic range. It is acting like a spring. If the elastic limit is exceeded then it is “bent” or permanently deformed. You see that as rolling on an edge. If the force continues then it will finialy break “chip”. This is all a function of the hardness or strength and varies with different materials. Mild steel for example can be bent back on itself without breaking. It is soft and is working in the plastic range. You can’t do that with a file. Very hard materials have an elastic range and a very narrow plastic range. They are said to be brittle. The more alloy that is put into a knife steel at a given hardness will tend to narrow the plastic range. This is also a function of the hardness. Very high hardness blades have a narrow plastic range and will flex some, bend just a little and then break. You mentioned several knife blade steel grades. All have different mechanical charteristics and the challenge is to understand how the material acts, heat treat and grind to get the best balance of properties. A fine grain like you find in the particle steels will tend to be less brittle than a more course grain wrought base steel. If you want a blade that will fail by rolling at the edge then it will need a softer heat treat. If you want a very strong edge that will stand there, and hold the carbides in place for maximum wear then it has to be harder or stronger. For example look at CPM S90V. A fine grain base so it is inherently strong but full of alloy, so that tends to offset the ductility. Heat treat it hard (RC 60 +) so it will not bend at the edge and hold the hard vanadium carbides in place to resist wear and you have a very wear resistant edge. Push it too hard during use and if the edge is too thin, not enough material to offset the stress and you have a breaking type failure (chipping). In addition to all this dynamic forces like chopping increase the felt force at the edge very quickly. So you have to choose the steel for the application, decide what qualities you want and heat treat and grind the edge to meet all those specifications. It’s all a fine balance and Spydeco does on **** of a job to meet all these requirement IMHO. Phil
Steel is going to respond differently in each knife due to shape and particular heat-treat. Even then, depending on what you cut and how it's done any blade can chip.
Most hard steels will chip at the point because they are stable at sustaining abuse per hardness that would send non-exotic steels running. A ZDP-189 blade at 65+ RC is stable for a fine edge. If you got 440c or AUS-8 to that level (if it could be done), I speculate it would be about as stable as glass.
I think anyone can have a thick ground ZDP-189 knife. They probably won't ever realize problems with it but non-knife folks rarely care what they are doing or what the blade looks like anyways. Thin ground blades are more sensitive and knife snobs are more willing to pull out a jeweler's loop. Steels like VG-10, 154cm and even CPM-S30v (which is quite tough) is probably better for the average user and have better corrosive resistant properties.
If Spyderco gave us 45+ degree edges out of the box we would never notice chipping. We would also not have the same definition of the word "sharp". :D
Most hard steels will chip at the point because they are stable at sustaining abuse per hardness that would send non-exotic steels running. A ZDP-189 blade at 65+ RC is stable for a fine edge. If you got 440c or AUS-8 to that level (if it could be done), I speculate it would be about as stable as glass.
I think anyone can have a thick ground ZDP-189 knife. They probably won't ever realize problems with it but non-knife folks rarely care what they are doing or what the blade looks like anyways. Thin ground blades are more sensitive and knife snobs are more willing to pull out a jeweler's loop. Steels like VG-10, 154cm and even CPM-S30v (which is quite tough) is probably better for the average user and have better corrosive resistant properties.
If Spyderco gave us 45+ degree edges out of the box we would never notice chipping. We would also not have the same definition of the word "sharp". :D
The only steel I've had to deal with in that regard is vg-10. I haven't had a problem with chipping/rolling with any of the other steels mentioned. I did roll the edge on my temp2 by accidently banging the edge against a steel sink pretty hard, but most of it steeled out quite easily and it touched up well. Had to do a lot of repair of a broken, chipped Damascus mule due to outright abuse, but it seemed pretty forgiving and I was able to rehabilitate it with a few hours work and the support of folks here.
S30V and zdp I've not had any problems with although both have been used quite a bit. Then again I use my knives for cutting, not chopping or prying. When cutting I always try to excercise a little bit of thought beforehand. When I need to chop something I'll bring out the hatchet.
All of these steels are fantastic compared to what I had available 20 years ago, not that I dwell on the past, rather rejoice in the future of other innovations that might be coming.
S30V and zdp I've not had any problems with although both have been used quite a bit. Then again I use my knives for cutting, not chopping or prying. When cutting I always try to excercise a little bit of thought beforehand. When I need to chop something I'll bring out the hatchet.
All of these steels are fantastic compared to what I had available 20 years ago, not that I dwell on the past, rather rejoice in the future of other innovations that might be coming.
Charlie
" Everything should be made as simple as possible, but not one bit simpler."
[CENTER]"Integrity is being good even if no one is watching"[/CENTER]
" Everything should be made as simple as possible, but not one bit simpler."
[CENTER]"Integrity is being good even if no one is watching"[/CENTER]
The only chipping i encountered was with my ZDP Delica, cutting zip ties. It was sharpened really low, probably 20 inclusive or so. I think for *most* cutting chores it would have been fine but cutting a thick hard plastic zip tie was too much. Since then i've been sharpening to 25-28ish inclusive which doesn't sound like much of a difference but it has been enough that i haven't had chipping issues since, and i have cut zip ties with it since. Now the worst i get is a shiny spot on the edge.
All SE all the time since 2017
~David
~David
The absolute tip of my Rock Salt rolled while I was cutting up a fish. It was just the extreme tip that did, barely noticeable. I was a little disappointed and never got it perfect again, although I tried. That was partially the reason why I sold it (and yes I overstated the problem to the buyer, exaggerating how "bad" it was even though it was super minor) but not I totally regret selling it. I am very close to buying a Caspian Salt to hook up to my SCUBA BC though.
Most of it depends on what the Steel is, how hard it is, what angle the edge is and what the blade is going to be used for.
In my testing cutting rope, now Manila rope is very abrasive and hard on edges, more so that most would believe then add on that I cut to 20 LBS of down pressure. That is a lot of pressure to be putting on a fine edge slicing through rope repeatably. If you don't think 20 LBS is a lot go to your bathroom scale and put the knife edge on it and push down until you get to 20 LBS. That will give you an idea, then think about doing that repeatably for hundreds of times.
I have seen all kinda of failures, rolling, denting, chipping, flattening etc.
As Phil Wilson stated there is a fine balance that has to be met.
In my testing cutting rope, now Manila rope is very abrasive and hard on edges, more so that most would believe then add on that I cut to 20 LBS of down pressure. That is a lot of pressure to be putting on a fine edge slicing through rope repeatably. If you don't think 20 LBS is a lot go to your bathroom scale and put the knife edge on it and push down until you get to 20 LBS. That will give you an idea, then think about doing that repeatably for hundreds of times.
I have seen all kinda of failures, rolling, denting, chipping, flattening etc.
As Phil Wilson stated there is a fine balance that has to be met.
Chipping on my Delica 4
Hi, what do you think of my Delica 4 full flat grind, chipping in two separate spots just while I was trying to open a walnut by inserting the blade in the soft bottom and slightly rotating the knife to open it.
I was quite surprised by this as I didn't apply very much force.
The chipping was just about 6mm from the tip and the chips were about 1 mm deep so I had to resharpen the hole blade quite a lot before leveling them.
I hope that the blade hasn't any structural defect, is there any way I could test it?
Thanks
I was quite surprised by this as I didn't apply very much force.
The chipping was just about 6mm from the tip and the chips were about 1 mm deep so I had to resharpen the hole blade quite a lot before leveling them.
I hope that the blade hasn't any structural defect, is there any way I could test it?
Thanks
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jackknifeh
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The only steels I'm familiar with as a result of use is AUS-8, VG-10 and ZDP-189. The following is my general experience when using a knife properly. I don't baby it but I don't drop it on the sidewalk either.
AUS-8: Good, just gets dull with use as expected. No chipping noticed. Easily sharpened.
VG-10: Better, just gets dull with use as expected but not as quickly. Sharp edge lasts longer. No chipping noticed. Easily sharpened.
ZDP-189: Great edge retention. Stays very sharp even after 1.5 hours of whittling on a green tree branch I just cut off a tree. BUT, with low angles (<18 deg.) the edge chips when hitting something as soft as a copper electrical wire while stripping the insulation off and using a little side pressure. Very small chips that are hard to see and doesn't effect overall performance. No problem to sharpen, just takes a little longer.
So, go for lower angles on AUS-8 and VG-10 for slicing stuff and don't really worry about chipping. They shouldn't roll unless you are putting side to side force on the edge (which will happen). Go for lower angles with ZDP-189 ONLY if you are cutting realitivly soft stuff like food, cardboard, stuff like that and keep the side force to a minimum. Cardboard may dull an edge faster than a tomato but it shouldn't make it chip. With ZDP-189 I put a 20 to 22 degree per side edge on the very edge no matter how low the back bevel is and I haven't had any problem with chipping. For subsequent sharpenings just hit the edge a few strokes at the same 20 - 22 angle and it will sharpen quickly with very little steel being removed. For me a back bevel of 10 deg. per side is as low as I would ever go for any EDC knife.
This is only my opinion based on limited experience with the type of use my knives go through.
Jack
AUS-8: Good, just gets dull with use as expected. No chipping noticed. Easily sharpened.
VG-10: Better, just gets dull with use as expected but not as quickly. Sharp edge lasts longer. No chipping noticed. Easily sharpened.
ZDP-189: Great edge retention. Stays very sharp even after 1.5 hours of whittling on a green tree branch I just cut off a tree. BUT, with low angles (<18 deg.) the edge chips when hitting something as soft as a copper electrical wire while stripping the insulation off and using a little side pressure. Very small chips that are hard to see and doesn't effect overall performance. No problem to sharpen, just takes a little longer.
So, go for lower angles on AUS-8 and VG-10 for slicing stuff and don't really worry about chipping. They shouldn't roll unless you are putting side to side force on the edge (which will happen). Go for lower angles with ZDP-189 ONLY if you are cutting realitivly soft stuff like food, cardboard, stuff like that and keep the side force to a minimum. Cardboard may dull an edge faster than a tomato but it shouldn't make it chip. With ZDP-189 I put a 20 to 22 degree per side edge on the very edge no matter how low the back bevel is and I haven't had any problem with chipping. For subsequent sharpenings just hit the edge a few strokes at the same 20 - 22 angle and it will sharpen quickly with very little steel being removed. For me a back bevel of 10 deg. per side is as low as I would ever go for any EDC knife.
This is only my opinion based on limited experience with the type of use my knives go through.
Jack
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Ed Schempp
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Reread recommendation
On a side note: take time to reread Phil Wilson's post. Phil has been using Crucible metals for a long time. He has been getting the material shipped to him before the steels are released so Crucible knows how they will react in the real world. Phil is one of the few custom makers that has a high temp kiln for the higher austenizing temps of Crucible products. Phil is retired from Livermore labs and has access to have his equipment calibrated, and has fine tuned the heat treatment for all the Crucible products that he uses in his knives.
I've known Phil for about 15 years. When I saw Phil's filet knives I breathed sigh of relief, I knew that I would probably not build another filet knife. I would just send those customers to Phil, to get the best filet knife made.
Besides knowing his material and taking the time to explain some fine points, Phil is a gentleman and a good guy. Thanks for bringing your expertise to the forum...Take Care...Ed
I've known Phil for about 15 years. When I saw Phil's filet knives I breathed sigh of relief, I knew that I would probably not build another filet knife. I would just send those customers to Phil, to get the best filet knife made.
Besides knowing his material and taking the time to explain some fine points, Phil is a gentleman and a good guy. Thanks for bringing your expertise to the forum...Take Care...Ed
Yup. :DEd Schempp wrote:On a side note: take time to reread Phil Wilson's post. Phil has been using Crucible metals for a long time. He has been getting the material shipped to him before the steels are released so Crucible knows how they will react in the real world. Phil is one of the few custom makers that has a high temp kiln for the higher austenizing temps of Crucible products. Phil is retired from Livermore labs and has access to have his equipment calibrated, and has fine tuned the heat treatment for all the Crucible products that he uses in his knives.
I've known Phil for about 15 years. When I saw Phil's filet knives I breathed sigh of relief, I knew that I would probably not build another filet knife. I would just send those customers to Phil, to get the best filet knife made.
Besides knowing his material and taking the time to explain some fine points, Phil is a gentleman and a good guy. Thanks for bringing your expertise to the forum...Take Care...Ed
Phil is an awesome guy and can really do some real magic Heat Treating. :)
With that Custom Furnace he can really tweak the tempering process to make the steels do pretty much whatever he wants. I have seen the results first hand and it is simply amazing.
I think a knife, especially one with a thin flat ground edge, is not the proper tool to be opening nuts with. As explained in detail by various posters above, twisting puts a lot of stress on a thin edge. Knives are designed to cut, not to screw, twist, pry, etc. The reason your knife failed was because it was subjected to abuse. Next time, why not use a nut cracker which is a tool that is designed to open nuts.windmill wrote:Hi, what do you think of my Delica 4 full flat grind, chipping in two separate spots just while I was trying to open a walnut by inserting the blade in the soft bottom and slightly rotating the knife to open it.
I was quite surprised by this as I didn't apply very much force.
The chipping was just about 6mm from the tip and the chips were about 1 mm deep so I had to resharpen the hole blade quite a lot before leveling them.
I hope that the blade hasn't any structural defect, is there any way I could test it?
Thanks
Peter - My :spyder:'s:
Caly~3.5 (VG-10 & S. Blue); Para2~(20CP~M390~S30v); Military~(M390~S30v); Endura & Delica~4~FFG; Native~(S30v); Caly~Jr.~(ZDP); Manix~2~(M4); Ladybug~3~(VG-10. SE); Mules~(M390).
Caly~3.5 (VG-10 & S. Blue); Para2~(20CP~M390~S30v); Military~(M390~S30v); Endura & Delica~4~FFG; Native~(S30v); Caly~Jr.~(ZDP); Manix~2~(M4); Ladybug~3~(VG-10. SE); Mules~(M390).
solid zdp-189 delica 4 easily chips, and all I cut with it was boxed wall cardboard. will not recommend zdp-189 for cutting cardboard...it CHIPS easily.arty wrote:I have never had a knife blade chip, but I don't use hard steel blades on metal. You can take a Stanley wood chisel and chop through wood into concrete - and get chipping. A harder steel will also chip out on concrete.
I have never had any blade chip using 440C, D2, M2, 154cm, ATS34, VG10, or ZDP-189. I don't normally get chipping with any blade - if I am careful about use.
I wouldn't be surprised if you get chipping if you chop with a knife on very hard wood knots and the blade is ground very thin. That is why axes are generally softer steel with convex grinds.