Aside from my Wegner jr. which goes everywhere I go, my other knife interests are related to fishing. I'm constantly on the prowl for better fillet knives. The best I own is a custom job which I purchased through a forum contact more than a year ago. The blade is "modified 440A", resists corrosion, holds and edge quite well, and can be sharped like a razor. Knives for this purpose, as I understand it, are a compromise between cutting/edgehold and corrosion resistance. Typically AUS 6,8,10 and 440A are the steels I see used. Is 440C adequately corrosion resistant and will it hold an edge a great deal better than A? Is VG 10 used for these kinds of blades? What in your experience is the best steel curently available for this application? Thanks, Jack
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fillet knife steels
- Thread starter jackG
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Is 440C adequately corrosion resistant and will it hold an edge a great deal better than A? Is VG 10 used for these kinds of blades?
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No it´s not as corrosion resistant as the 440A, and Yes it will hold an edge better. The VG10 steel will hold an edge much longer than the other two but truth to say, I´ve never seen a fillet knife made out of this steel.
The fillet knives I use myself are an EKA folding fillet (Sandvik 12C27, HRC 58), Opinel fillet (DIN steel?), Martiini fillet (also Sandvik) and Gerber fillet (440A). I´m quite satisfied with all of them and don´t see any big differences. Maybe is the Sandvik steel slightly more corrosion resistant than the others.
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dePaul
I beg to differ.
440A and 440C have the SAME chromium content. But 440C has a higher carbon content which allows a higher hardness to be reached thus better edge retention.
How can 12C27 be more corrosion resistant than 440C, 12c27 only has 13.5% chromium whereas 440C has 16-18%.
In my test 12C27 and ATS-34 both stain and rust much easier than 440C as both have MUCH lower chromium contents.
Oh and welcome Jack!!!
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Robert
Flat Land Knife Works
rdblad@telusplanet.net
http://members.tripod.com/knifeworks/index.html
I beg to differ.
440A and 440C have the SAME chromium content. But 440C has a higher carbon content which allows a higher hardness to be reached thus better edge retention.
How can 12C27 be more corrosion resistant than 440C, 12c27 only has 13.5% chromium whereas 440C has 16-18%.
In my test 12C27 and ATS-34 both stain and rust much easier than 440C as both have MUCH lower chromium contents.
Oh and welcome Jack!!!
------------------
Robert
Flat Land Knife Works
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Euhhh,
Chrome content is not the only thing that makes a steel corrosion resistant, by far.
It just is the most used. Nickel is a good one too, along with a lot of others.
And, chemically seen, 12C27 has less chrome, but is more corrosion resistant. But this can also be because it is easier to polish.
In order off suitability for filleting knives,
1. 12C27
2. 440A
3. 420HC
4. 440B
5. 440C
Most other steels are not corrsoion resistant enough. ATS nor VG-10 are corrsion enough.
There are also some other steels out here, like 19C27 (12C27 with more carbon), forged stainless (because of carbonloss on the surface much more corrosion resistance),
Coatings ( if you just cut fish, it could last a long time)....
But you could look into Cobalt (David Boye),
Titanium........
greetz, Bart.
------------------
"If the world wouldn't SUCK, we'd all fall off !"
member of the BKS
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Chrome content is not the only thing that makes a steel corrosion resistant, by far.
It just is the most used. Nickel is a good one too, along with a lot of others.
And, chemically seen, 12C27 has less chrome, but is more corrosion resistant. But this can also be because it is easier to polish.
In order off suitability for filleting knives,
1. 12C27
2. 440A
3. 420HC
4. 440B
5. 440C
Most other steels are not corrsoion resistant enough. ATS nor VG-10 are corrsion enough.
There are also some other steels out here, like 19C27 (12C27 with more carbon), forged stainless (because of carbonloss on the surface much more corrosion resistance),
Coatings ( if you just cut fish, it could last a long time)....
But you could look into Cobalt (David Boye),
Titanium........
greetz, Bart.
------------------
"If the world wouldn't SUCK, we'd all fall off !"
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Cold Steel offers fillet knives in its Carbon V, I think with epoxy coating. Should work fine but you'd have to dry them after use. Frankly, I think corrosion resistance s nice but not essential. My carbon steel knives are mostly mottled from use; keeping them rust free is not difficult.
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I have a custom made with 440C, ten years and not a stain on it. I think the mirror finish helps corrosion resistance. I do have to put a steel to it frequently - the RC was kept low to preserve flexibility.
Hefty, right hand grooved, ironwood scales make it pretty and easy to clean. Best fillet knife I've ever owned. 440C is up to the job.
Hefty, right hand grooved, ironwood scales make it pretty and easy to clean. Best fillet knife I've ever owned. 440C is up to the job.
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Originally posted by Bart student:
Euhhh,
Chrome content is not the only thing that makes a steel corrosion resistant, by far.
-----------------------------------------
Thanks Bart student. You nailed it pretty well. Couldn´t said it better myself. The matter of corrosion resistance is more complicated than just looking at the level of chromium. And I also go with your scale of suitability of the different steel types
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For the sake of argument. If the finish is the same where does 12C27 get its corrosion resistance from to be more corrosion resistant than 440C?????
12C27
C .6 MN .4 SI .4 CR 13.5
440C
C 1.2 MN 1.0 SI 1.0 CR 16-18 MO .75
I used 12C27 for awhile but found it no more corrosion resistant than ATS-34. Had 3 boning knives tested in a butcher shop all had mirror polished blades and the only one that didn't rust was the 440C.
------------------
Robert
Flat Land Knife Works
rdblad@telusplanet.net
http://members.tripod.com/knifeworks/index.html
12C27
C .6 MN .4 SI .4 CR 13.5
440C
C 1.2 MN 1.0 SI 1.0 CR 16-18 MO .75
I used 12C27 for awhile but found it no more corrosion resistant than ATS-34. Had 3 boning knives tested in a butcher shop all had mirror polished blades and the only one that didn't rust was the 440C.
------------------
Robert
Flat Land Knife Works
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Ditto Alberta Ed. Unless you're filleting fish for a living, wiping down your knife is no big deal. The Cold Steel Filet knives are great. The advantage of Carbon V is that it probably keeps a better edge than any "stainless" (possibly excepting customs with 420V and such), yet with flexibility and strength.
I fish almost exclusively in salt water and therefore had discounted non-stainless steel blades for fishing knives. What a day on the water can do to carbon steel is almost unbelievable. I'll bet they're be great in fresh water though.
I've owned some pretty spendy over-the- counter stainless knives which got absolutely hammered by filleting half a dozen saltwater rockfish. The edge would go away in minutes and later when resharpening the cutting edge would flake out on spots as if it had been eaten away. I speculated that it was due to some chemical action of the salt. It seemed incomprehensible that stainless steel, with a 58-60R rating would fold up like that from cutting on a few wimpy little fish. The makers whose blades behaved that way included Gerber, Shrade and Buck. One of the forum experts suggested it was due to improper heat treat. That, I think, makes more sense than chemical action.
The custom kife I've got is 440A. It sharpens spectaculary but I would like more edge holding (who wouldn't?). The higher C content of 440C ought to help. I noticed that Lakota knives makes a inexpensive fillet knife in 440C. That might be a low cost way to test for increased edge holding fo that steel. Of course, I'll also need to round up enough fish to conduct the experiement. The lengths we go to catch fish and monkey with knives, tests even the most long suffering wives.
One other question. Is the Rockwell scale rating the absolute measurement of a blade's edge holding capability? Or, are there some steels with a lower rating, which hold an edge longer than blades with a higher rating? Thanks again for the info. Jack
I've owned some pretty spendy over-the- counter stainless knives which got absolutely hammered by filleting half a dozen saltwater rockfish. The edge would go away in minutes and later when resharpening the cutting edge would flake out on spots as if it had been eaten away. I speculated that it was due to some chemical action of the salt. It seemed incomprehensible that stainless steel, with a 58-60R rating would fold up like that from cutting on a few wimpy little fish. The makers whose blades behaved that way included Gerber, Shrade and Buck. One of the forum experts suggested it was due to improper heat treat. That, I think, makes more sense than chemical action.
The custom kife I've got is 440A. It sharpens spectaculary but I would like more edge holding (who wouldn't?). The higher C content of 440C ought to help. I noticed that Lakota knives makes a inexpensive fillet knife in 440C. That might be a low cost way to test for increased edge holding fo that steel. Of course, I'll also need to round up enough fish to conduct the experiement. The lengths we go to catch fish and monkey with knives, tests even the most long suffering wives.
One other question. Is the Rockwell scale rating the absolute measurement of a blade's edge holding capability? Or, are there some steels with a lower rating, which hold an edge longer than blades with a higher rating? Thanks again for the info. Jack
I used to fish in saltwater (around Sydney, Australia) about twice a week (see http://www.cse.cuhk.edu.hk/~phwl/fishing.html for some photos). For cutting bait, cleaning fish etc, I would use a cheap Frosts knife, often cutting on rocks etc, clean it in saltwater and put it back in my fishing bag for next time. It did rust, but not that badly, and I would give it an edge every year or so on a sanding belt.
I normally clean the fish first and fillet at home or at the boat ramp. I've used several different filleting knives including the Buck folding one and the Kershaw one and never had a problem with rust since it gets washed in fresh water immediately afterwards. I never had a problem with them getting blunt quickly either so I guess for me, almost any reasonable filleting knife is ok.
I don't sharpen my filleting knife too often because I find it difficult to skin fish with a razor sharp filleting knife since it cuts through the skin too easily. After it has got slightly blunt, it takes the skin off much better. Does anybody else have an opinion on this?
jackG - do you use your Wegner Jr in fishing situations or just utility purposes? I'm considering buying one for camping, cutting fishing line etc but I'm not sure I like the shape of the blade.
I normally clean the fish first and fillet at home or at the boat ramp. I've used several different filleting knives including the Buck folding one and the Kershaw one and never had a problem with rust since it gets washed in fresh water immediately afterwards. I never had a problem with them getting blunt quickly either so I guess for me, almost any reasonable filleting knife is ok.
I don't sharpen my filleting knife too often because I find it difficult to skin fish with a razor sharp filleting knife since it cuts through the skin too easily. After it has got slightly blunt, it takes the skin off much better. Does anybody else have an opinion on this?
jackG - do you use your Wegner Jr in fishing situations or just utility purposes? I'm considering buying one for camping, cutting fishing line etc but I'm not sure I like the shape of the blade.
In answer to PHWL. The W.jr is a wonderful utility knife. I studied all this stuff for months before deciding on it that knife. It is so solid, compared to all the other folders I've handled, it inspires confidence. The grip fits the hand really well. It might be a bit small for someone with really large hands, but that's a guess. I haven't used it to whack on fish but it goes along everywhere. It cuts line, sandwiches, etal.
db - I've wondered what kind of steel DR uses. It sharpens really well, resists corrosion, but I thought it was a bit soft for C, but that is speculation. It reminds me of the steel Case uses in some of it's non-flex blade fillet knives, like the Coho, I think. I've bugged dealers about the kind of steel DR uses and they just say it's "high carbon." (But so is a pencil lead, for that matter-it didn't tell me much.) You might be right though. The heat treat could determine the hardness and they may keep it a little lower on the R scale. Does anyone know for sure what DR blades are made of? Jack
db - I've wondered what kind of steel DR uses. It sharpens really well, resists corrosion, but I thought it was a bit soft for C, but that is speculation. It reminds me of the steel Case uses in some of it's non-flex blade fillet knives, like the Coho, I think. I've bugged dealers about the kind of steel DR uses and they just say it's "high carbon." (But so is a pencil lead, for that matter-it didn't tell me much.) You might be right though. The heat treat could determine the hardness and they may keep it a little lower on the R scale. Does anyone know for sure what DR blades are made of? Jack
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In regards to chromium content and 'stainlessness', I think it is the Most important factor. The problem is that the percentage chromium in the alloy does Not tell you the amount of FREE chromium in a hardened and tempered blade. My understanding is that 440A really is more corrosion resistant than 440C, even though they Appear to have the same chromium (Cr) content.
The reason for this is that the anti-corrosion protection produced by chromium is a Surface phenomenom. Free chromium oxidizes to chromium oxide in a one-molecule thick, self-repairing and invisibile surface layer. It is this protective coating which inhibits oxidation of iron deeper in the blade. Mirror finishes help by minimizing surface area for oxidation on the blade. It reduces the size of pits and scratches which may break the chromium oxide surface layer and allow oxidizing agent like chloride ions (from salt) to oxidize iron to ferrous oxide (red rust).
Chromium is a strong Carbide former. It chemically combines with Fe and Carbon in making rigid crystal structures that make blades harder and hold edges longer. Low chromium steels like 52100 hold edges better than some other steels because of the less than 1% chromium content. This is not nearly enough to add any corrosion prevention, however. It takes about 12% FREE chromium (that not bound up in carbides) in a finished blade to make a steel 'stain resistant'.
The addtional carbon in 440C (1%) compared to 440A (0.6%) will make the blade harder and more wear resistant given the same heat treating conditions by producing more hard iron and carbon 'carbides'. But it will also soak up more of the available Chromium, reducing the amount of Free chromium in the metal.
The bottom line is that it is an error to expect that the absolute amount of chromium in a steel correlates exactly with corrosion resistance. The amount of free chromium is a good predictor of oxidation inhibition. But the amount of free chromium depends on the concentration of other elements in the steel, and the ways these effect the final unbound (free) chromium in the metal.
In regards to RC scales and edge-holding: there is a rough correlation here. However, all steels at RC58 will NOT be equivalent in edge holding. Some will be better than others. This is because the RC scale only measures resistance to Penetration. Not wear resistance, toughness, malleablility, or ductility. These physical properties of steels are influenced by the alloying elements in the metal. The final combination of elements into crystals of different sizes is determined in the heat-treating steps of quenching (hardening) and tempering (softening). Every steel has its own unique characteristics. Too much is made recently of having very high (eg RC62) hardenesses. This will produce better wear resistance, but will often be associated with brittleness (low resistant to mechanical forces like bending).
Some steels make fine blades at RC60-62. Some do not. Most simple carbon steels have a nice balance of edge holding and toughness in an all hard blade tempered at RC56-58. Smaller blades for slicing can be left harder. Larger blades for chopping and prying need to be tempered a little softer to add toughness.
Some blade materials like Talonite (not really a steel at all since its principle ingredient is Cobalt, not iron) have RC values in the mid 40's. This is very very low by steel standards. On the other hand, talonite seems to outperform many iron containing blade steels in the edge holding departments. Its physical properties are quite different from steel.
It is not realistic to compare RC values of cobalt alloys and iron alloys to compare potential edge holding. Or even to compare RC values of regular knife steels to predict performance as a knife. And folks like the bladesmiths of the ABS practice differential heat-treatments, producing blades with hard edges, but soft backs and tangs, dramatically improving the overall performance of a steel.
Hope this rambling chemistry lesson helps. If I am wrong about any of this, please let me know
Paracelsus
[This message has been edited by Paracelsus (edited 10-23-2000).]
The reason for this is that the anti-corrosion protection produced by chromium is a Surface phenomenom. Free chromium oxidizes to chromium oxide in a one-molecule thick, self-repairing and invisibile surface layer. It is this protective coating which inhibits oxidation of iron deeper in the blade. Mirror finishes help by minimizing surface area for oxidation on the blade. It reduces the size of pits and scratches which may break the chromium oxide surface layer and allow oxidizing agent like chloride ions (from salt) to oxidize iron to ferrous oxide (red rust).
Chromium is a strong Carbide former. It chemically combines with Fe and Carbon in making rigid crystal structures that make blades harder and hold edges longer. Low chromium steels like 52100 hold edges better than some other steels because of the less than 1% chromium content. This is not nearly enough to add any corrosion prevention, however. It takes about 12% FREE chromium (that not bound up in carbides) in a finished blade to make a steel 'stain resistant'.
The addtional carbon in 440C (1%) compared to 440A (0.6%) will make the blade harder and more wear resistant given the same heat treating conditions by producing more hard iron and carbon 'carbides'. But it will also soak up more of the available Chromium, reducing the amount of Free chromium in the metal.
The bottom line is that it is an error to expect that the absolute amount of chromium in a steel correlates exactly with corrosion resistance. The amount of free chromium is a good predictor of oxidation inhibition. But the amount of free chromium depends on the concentration of other elements in the steel, and the ways these effect the final unbound (free) chromium in the metal.
In regards to RC scales and edge-holding: there is a rough correlation here. However, all steels at RC58 will NOT be equivalent in edge holding. Some will be better than others. This is because the RC scale only measures resistance to Penetration. Not wear resistance, toughness, malleablility, or ductility. These physical properties of steels are influenced by the alloying elements in the metal. The final combination of elements into crystals of different sizes is determined in the heat-treating steps of quenching (hardening) and tempering (softening). Every steel has its own unique characteristics. Too much is made recently of having very high (eg RC62) hardenesses. This will produce better wear resistance, but will often be associated with brittleness (low resistant to mechanical forces like bending).
Some steels make fine blades at RC60-62. Some do not. Most simple carbon steels have a nice balance of edge holding and toughness in an all hard blade tempered at RC56-58. Smaller blades for slicing can be left harder. Larger blades for chopping and prying need to be tempered a little softer to add toughness.
Some blade materials like Talonite (not really a steel at all since its principle ingredient is Cobalt, not iron) have RC values in the mid 40's. This is very very low by steel standards. On the other hand, talonite seems to outperform many iron containing blade steels in the edge holding departments. Its physical properties are quite different from steel.
It is not realistic to compare RC values of cobalt alloys and iron alloys to compare potential edge holding. Or even to compare RC values of regular knife steels to predict performance as a knife. And folks like the bladesmiths of the ABS practice differential heat-treatments, producing blades with hard edges, but soft backs and tangs, dramatically improving the overall performance of a steel.
Hope this rambling chemistry lesson helps. If I am wrong about any of this, please let me know
Paracelsus
[This message has been edited by Paracelsus (edited 10-23-2000).]
Paracesus - that is very useful information. I had read someplace before that the 440C would not be quite as corrosion resistant as A, and you've given some indication why. I think I really need to pick up a 440C fillet knife.
One thing still puzzles me. I've got a Kershaw and a Gerber f. knife which I tossed in a drawer as nearly useless. The edges will go dull while filleting a couple of fish. No matter how carefully or quickly I wipe them down afterward, they spot - like a water spot. And where the spots appear on the beveled cutting edge, when sharpened later, that tiny bit of steel flakes out. This leaves a pit right on the cutting edge, which is of course then dulled. Here's the kicker. The blades are so hard that even using new Spyderco ceramic bench stones it takes discouragingly long to take out he pits. Then 5 minutes into a fillet job they will do it again. I can't understand how the edge can go that quickly and the yet the steel be so hard to resharpen. At any rate it makes the blades useless to me. Thanks, Jack.
One thing still puzzles me. I've got a Kershaw and a Gerber f. knife which I tossed in a drawer as nearly useless. The edges will go dull while filleting a couple of fish. No matter how carefully or quickly I wipe them down afterward, they spot - like a water spot. And where the spots appear on the beveled cutting edge, when sharpened later, that tiny bit of steel flakes out. This leaves a pit right on the cutting edge, which is of course then dulled. Here's the kicker. The blades are so hard that even using new Spyderco ceramic bench stones it takes discouragingly long to take out he pits. Then 5 minutes into a fillet job they will do it again. I can't understand how the edge can go that quickly and the yet the steel be so hard to resharpen. At any rate it makes the blades useless to me. Thanks, Jack.
Cliff Stamp
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My first guess would be that you are leaving a wire edge on the blades which is quickly breaking off during use as it seems unlikely that the edges would roll/impact or wear that quickly given your experience with sharpening. However if you only experience this with those knives it is not likely that a wire edge is the problem. It is easily checked anyway.
Corrosion seems to be an obvious problem however I have never even seen plain carbon steels rust that fast, a couple of fish and then dull. However I would note that blades which do take edge damage by corrosion need to have all the corroded metal removed. Unless the edge is fresh it will break apart easily during use. The next time you are sharpening them. Use an x-coars hone and use say 50-100 strokes after you have generated a full burr to insure all the degraded material has been removed.
As for fillet blade steel, I like 420V heat treated by Phil Wilson to 59 RC. It is durable enough to resist impacts and fractures and wears slowly. No problems with corrosion either and it has seen significant salt water use.
-Cliff
[This message has been edited by Cliff Stamp (edited 10-24-2000).]
Corrosion seems to be an obvious problem however I have never even seen plain carbon steels rust that fast, a couple of fish and then dull. However I would note that blades which do take edge damage by corrosion need to have all the corroded metal removed. Unless the edge is fresh it will break apart easily during use. The next time you are sharpening them. Use an x-coars hone and use say 50-100 strokes after you have generated a full burr to insure all the degraded material has been removed.
As for fillet blade steel, I like 420V heat treated by Phil Wilson to 59 RC. It is durable enough to resist impacts and fractures and wears slowly. No problems with corrosion either and it has seen significant salt water use.
-Cliff
[This message has been edited by Cliff Stamp (edited 10-24-2000).]
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Very interesting info Paracelsus!
Am I reading this correctly....?
It is possible that a lower RC in say...440C, might result in greater corrosion resistance...depending opon the quenching and tempering process, because of more free Cr?
Thanks again!
[This message has been edited by Steve-O (edited 10-25-2000).]
Am I reading this correctly....?
It is possible that a lower RC in say...440C, might result in greater corrosion resistance...depending opon the quenching and tempering process, because of more free Cr?
Thanks again!
[This message has been edited by Steve-O (edited 10-25-2000).]
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I didn't say that Steve-O. It is an interesting question, but my guess is that the final RC hardness of the steel after tempering does not change the amount of free chromium enough to make difference.
The chromium gets tied up rather significantly during annealing (softening before grinding). The blade is cooled very slowly, and large complex crystals form. To heat treat a blade after shaping, it is heated to very high temperatures (above 1800F), which breaks all the chemical associations in the metal, and then cooled rapidly, which causes crystals of martensite to form (the really hard stuff). How fast the quench is depends on the steel. Simple tool steels are often oil quenched. Stainless steel are often air quenched.
After quenching, the blade is tempered by heating at relatively low temperatures (a few hundred degrees). This melts some of the Martensitic matrix into more pliable, plastic, and amorphous glass-like material with imbedded carbide crystals,
I am not at all sure whether tempering releases more bound chromium, or decreases the free chromium concentration. In the 'stainless' steel thread in this forum (see link below), there is some additional information you should read. 440C in the annealed state has only 7% free chromium and could not be considered stainless. However, in the hardened and tempered state, the free chromium is well above 12%. I doubt small changes in hardness (RC) would change the chromium content enough to make a difference since steels with a free chromium level above 12% are essentially all equally corrosion resistant. Dropping free chromium to 10% or less will dramatically reduce corrosion resistance. So, the answer is Good Question...I don't know. Anyone?
Why is is stainless steel stainless thread
Parambling
[This message has been edited by Paracelsus (edited 10-26-2000).]
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This is an interesting discussion, so I move it into the new general forum and am sending it BTT with this post. Have fun!