420V

T

tom mayo

Joined
Jan 27, 1999
Messages
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was reading the 440v thread below with great interest but it was toooooooo long so im starting this one.....first of all....440v and 420v in the mid fifties at hardness will still outperform just about ANYTHING else around (i said just about). the primary reason is the vanadium...thats what makes it work and it doesnt have to be that hard. but paul bos told me when you drop 440c below 56c rockwell (440v is 440v with a bunch of vanadium added and processed via particle metalurgy) the corrosion resistance goes OUT the window....one reason for maintaining the 57/58c hardness....a few points are not going to make the kind of difference in the vanadium particle metalurgy steels that they do in say ats 34...i know...i have been grinding this stuff...and i tell you 420v is harder annealed that almost anything else i use after it has been heat treated....the jury is still out on how tough it is... i am convinced that 440v should not be used in anything other than a small knife....it is brittle at 57 or 58...and the reason i know about the corrosion resistance thing is because i called paul and asked him to lower the rockwell for this very reason...he told me it wasnt a good idea...he heat treats steel for a living...i grind knives....i am very excited about talonite...have a few knives in the hands of some friends who hunt every weekend.....one guy cut up an eel the other day and said hes never had a knife work so good on that task...then he threw it in the cooler with some tako (octopus to you guys) and left it there cause i told him it wont rust....no rust....aloja

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Tom,

I echo your sentiments. The CPM stuff is amazing. And although I don't have a 420V blade, I'm confident that I understand the differences between it and the CPM440V that I do have many samples of. I also concur about 440V best serving in a smaller knife.

I read with great interest Steven Dick's review of Rob's big Talonite chopper in the Jan 2000 issue of TK. I've 2 fixed blades in the 4" range and one folder in Talonite and (no surprise to anyone) love the stuff. But in a blade bigger than 6 inches the jury has been out... at least we've seen some comments on a BIG blade now.

I wish I could recall the who and where but it seems about 4 or 5 years ago someone did test a large (9 or 10 inch) blade of CPM440V. Things are pretty foggy but I seem to remember having to read in between the lines about implied reservations or problems. You recall anything along those lines?

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-=[Bob Allman]=-

I did NOT escape from the institution! They gave me a day pass!

BFC member since the very beginning
AKTI membership pending
VHA and NRA member

 
I like to put toothy agressive edges on my knives and some steels won't take to this well like M-2 but 440V seems to take a this type of edge and so does ATS-34.Will 420v take an agressive edge?I read an article on 420V in Blade on Phil Wilsons use of this steel and he seems to think highly of this steel.Also I thought I read were Talonite won't take an agressive edge but instead favors a more polished type edge.Is this true?Thanks.
scott w
 
bob....havent been using 440v for long enough to know anything about 5 years ago.. was still using mostly ats then....and as for the aggressive edge...i would think both of these steels....420v and talonite (not a steel really but will call it that) would take an aggressive edge very well because they are primarily very wear resistant... i made a big semi skinner recently out of talonite and sharpened it with a 120 grit belt and gave it to my friend to try...he was very satisfied...it was a test knife.. i got it back....personally...i favor a finely sharpened and polished blade for almost everything...as i believe from extensive reading and experience that the smoother and finer the edge...the less resistance and better the knife will cut...that is my opinion and i know many will disagree with me..but i have been into knives for a long time and making them since late 1981...i have sharpened more knives than most people have ever seen (i sharpen tools for a living and can make a dull knife cut newspaper ribbons in about 45 sec...i am not bragging just stating a fact...i have a variable speed square wheel and a big buffer.) so thats my opinion...sincerely....tom...feel i have to add...one of the main reasons i feel so strongly about the fine vs coarse edge is that at the molecular level the coarse edge has much more of a tendency to bend and or break and wear faster as some of the edge is higher than the rest...thats how saw blades work....thus we have the serrated edge...and as a person who sharpens saw blades on a daily basis...if one or two teeth are higher than the rest....they are the only ones that work.....but i could give a long speech on why a coarse edge works better too i guess.. as a lot of this is just theory and personal experience....

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http://www.mayoknives.com




[This message has been edited by tom mayo (edited 10 October 1999).]
 
This cpm material and hardness is getting confusing.

Interesting that Cliff used D2 as a comparison in his tests.

Also interesting that Les thinks D2 is as good as any (previous post by him).

I think I would rather use D2 where I and makers know what we're dealing with.

Bottom line, there's not that much difference in performance, and the parameters are well known (for D2).

Although, I must admit I find it interesting that Perrin is experimenting with 440v after his spydie military test.

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Regards,
Ron Knight

Yeah I'm crazy, but what do you want me to do about it
 
Ron,

Fred Perrin has worked with CPM 440V before the Military review.

While visiting with him and Nemo in Paris, I saw a balisong that he made of 440V which was a very, very nice piece.

It is true, however, that Fred tends to work mostly with carbon steels.

I recently put Fred in touch with Rob Simonich, and if we are lucky, we can expect some Talonite projects from Fred in the near future.

Blues



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Live Free or Die

 
Tom, the problems that have been described with the 440V knives have all been when the edge was subject to enough stress to deform it. No one is saying the blades are not wear resistant.

Spyderco states 440V has better edge retention. However this is based on cutting card stock in a very controlled manner and I don't doubt what they say. I have done this myself and even with very soft steel blades (45 RC) could not get visible deformation in the edge. Yet no one is making 45 RC blades because exactly that would happen during actual use.

Tom, your point about different heights in very interesting. Ever think about collecting what you have learned about sharpening and edges, and writing some artices. I for one would love to read them.

-Cliff
 
420V will take an aggressive edge. So will M-2, the Benchmade M-2 blades anyway. Lately I have been sharpening my working knives with a course stone file I bought to sharpen my lawn mower blade. It is about the only way I have of sharpening 420V that doesn't drive me nuts. After I work up a slight burr, I strop the edge on dry ordinary cardboard. I consistently get an edge that will shave and cut very aggressively on anything. Will have to get back to you on the toughness of 420V, but if it is as good as ATS-34, that's good enough for me.

smile.gif
 
If you have problems with 420v and 440v being brittle shame on you . Read the mfgs specs.
56-58 rc is the recommended hardness. Try that and you will find that the toughness goes up and the edge retention is great.
I have comparied ats34 , 420v, 440v, 440c,. 440v and 420v out perform all the others. It is different to sharpen. Once you learn how it cut great...
If it is over hardened it will chip out as will any steel that is heat treated to harder than the mfg. specs
As for big knives I agree. I would make another choice for bigger knives.
ATS34, 440c, 52100, and other carbons are good steels for big knives..

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Web Site At www.infinet.com/~browzer/bldesmth.html
Take a look!!!




 
Here is a eamil I got in response to this post.
This is from a real user. Ill let it speak for itself. The knife he is speaking of has a 420v blade.
Darrel,
Just from the use I've put your apogee through I can tell it's a
better steel. Although edge geometry probably comes into it. I keep an edge
longer and I don't understand the bitching I have no problem sharpening it
at all. It's not even as difficult to do as with my ATS34 production
blades.
and those are supposed to be easier they're not recurve.
I just also wanted to tell you that your a through and through
bastard. You've totally ruined me when it comes to production knives! LOL!
I
bought a Spyderco Calypso Jr. cause I wanted a short blade, cheap knife
that
I wouldn't worry about losing when I'm on the road or in the airport. Well,
for a production knife it's nice, but it just doesn't stack up to the
apogee
at all, not even close. So I started in on my other knives. all the
production ones suck! Spyderco, Benchmade, Al Mar, Buck, Puma (remember
those) Gerber. Nada. Even the customs don't come up to the quality of
yours.
Although some aren't meant to.
You've just ruined me ;-) I just don't look at knives the same
anymore.
See ya at NY Custom Show. I'll be there Fri and Sat all day.

If you want his name please email me Ill be glad to get you in touch with him

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Web Site At www.infinet.com/~browzer/bldesmth.html
Take a look!!!




 
Hey,

I have recently been doing some comparisons between some of my ATS-34 blades by pounding them through a coat hanger. I used a REKAT Pioneer II, a Benchmade 830 Ascent, and a custom Black Cloud Sharktooth. All sustained similar edge damage with minor to severe chipping (the Ascent was not the worst!) and edge deformation.

My big A-2 Y2K Camp Knife cuts through the hanger wire with only some minor, barely visible edge chipping, and no deformation. I got slightly more damage on a 52100 tactical fixed blade.

I also tried a 420V Darrel Ralph Straight Krait. The strength and toughness of this stuff is outstanding. The edge suffered absolutely no visible damage at all. I really started wailing on it after initial effort resulted in no damage, but I never did hurt it. I don't know what the spec sheets say, but last night, in my garage, the 420V blade was the most durable, including A-2 and 52100. Maybe they should make bowies and big camp knives out of this stuff.

If you are going to buy a $400 handmade, "tactical" folding knife, the blade steel should be 420V, or you are not getting the best.
 
The more I learn, the less I realize that I know.

I DO have the CPM data sheets (thanks, Ed Schott), and am more confused after reading them.

Specifically, the CPM 420 V data sheet. In the discussion of toughness, it lists the toughness of 420V and 420V compared with the toughness of traditional steels. Both 420 and 440 are listed at two different hardening temperatures, with the lower hardening temperature having been tempered twice at the same temp. These different heat treatments yield only a point or two in Rc, yet have markedly different Charpy C-notch data.

The point of two of Rc (to only 58-59) was at the cost of roughly 30% to 50% decrease in toughness (Charpy C-notch).

My question to you experts is how do the current hardening/tempering temperatures compare with those used in these data, and how do the toughness of the steels produced with current heat treatment compare in toughness?

Thanks for shedding a little light. Walt
 
The Straight Krait has a moderately thick edge(before sharpening), but I have it sharpened at about 40 degrees included. So it is sort of a compromise in terms of edge geometry, a fine edge, but with lots of steel behind it. It is not a delicate edge. It is almost exactly like the edge on the Sharktooth(ATS-34) which chipped and deformed moderately. Darrel would have to supply the RcH, but above he seems to be saying that it should be in the 56-58 range.

If the results that I saw are meaningful, being very unscientifically obtained, I would add that the spec sheet toughness might not translate directly into edge durability. It sure looked to me like 420V was more durable than A-2 in this test, which is not what the comparative charpy numbers would suggest, nor what I have heard anybody else say they suspect up to now either. In particular, I think I remember both Kevin McClung and Rick from Mission knives writing that 420V was too brittle for combat knife applications. Mission knives then chose A-2 for their tool steel knives. It is possible that they were talking about gross brittleness, like the amount of bend the whole blade will take before snapping, rather than just edge durability when used to cut or chop hard materials.

[This message has been edited by Steve Harvey (edited 14 October 1999).]
 
This steel has been my favorite for two years
I find the same results . Its tough and holds a great edge for a good long while. I heat treat to 56-58 rc. The geometery on the apogee is a bit less of an angle that the krait . The apogee holds up just as well.
I have also done bend tests. This steel is as good or better than most that I tried..
As for a big knife. Yes I want to do a 10 in field knife with this steel . I need a buyer who wants great steel.
I do have a 6 in bladed Japanese style kitchen knife out there . The owner does not have to sharpen it very often :]. It is used on a glass chopping board ...


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Web Site At www.infinet.com/~browzer/bldesmth.html
Take a look!!!




 
Steve :

It sure looked to me like 420V was more durable than A-2 in this test, which is not what the comparative charpy numbers would suggest
Click to expand...

That is because they measure something different. Hardness would be critical to the coating hanger banger test. The harder the blade the more it would resist indenting (it would be less compressible) or side deformation (it would be stronger).

I remember both Kevin McClung and Rick from Mission knives writing that 420V was too brittle for combat knife applications.
Click to expand...

With a very low charpy value you will get a short impact life as fractures will propogate quickly and lead to gross failure. To be specific to your above hanger test. I would bet Mission A2 to do worse than the benchmade ATS-34 Ascent *in the sort term*. However if you kept at it the Mission would never do more than indent. Eventually the Ascent would start to fracture and then fail under similar levels of stress.

Darrel :

Yes I want to do a 10 in field knife with this steel . I need a buyer who wants great steel.
Click to expand...

I do. What kind of geometry are you thinking of?

-Cliff

[This message has been edited by Cliff Stamp (edited 15 October 1999).]
 
Per the spec sheet at Cliff's site 420V at the lower hardness levels, Rc 55 to 56, can be as tough as D2 at Rc 59 or 440C at similar levels, but it seems to drop off quickly as the hardness goes up. Fairly large changes in toughness with small changes in hardness and tempering make it difficult to compare different steels, one really needs to compare curves, and that isn't considering cyro treatments which can evidently result in large improvements in toughness. This thread is also interesting as the 420V is evidently being used at kind of low hardness levels, at least compared to a lot of the Rc60 and higher blades that seem common. From what little I've seen 420V would work fine in a large knife if the thickness is adequate and as long as heavy prying and especially high impact loads on the side of the blade are avoided, with maybe no more concern than with using D2.
 
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