BM steel question

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midget
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BM steel question

Postby midget » Sat Sep 07, 2002 12:00 am

I'm on a question asking roll here...



And maybe it's not right to talk about other blades in the Spyderco forum. I once heard Mr. Glesser (It's not Sal cause I'm still a kid) say that it's fair game to converse about different companies, and that's very noble.



So, does anyone know anything about this "M2" steel that BM uses for stuff like the Nimravus? Good, bad? Rusts?









-edited for spelling



Edited by - midget on 9/7/2002 11:41:48 PM

sc_rebel1957
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Postby sc_rebel1957 » Sun Sep 08, 2002 12:42 am

I'm told M-2 and A-2 are the same thing? I sometimes carry a Panther Mod 401 which a fellow forum member was a lot of help in identifying it for me. I like the way it feels and i have'nt had any rust on it yet BM lists it as 57-59 Rc. The edge is too think for my taste and it's 60/40 serrated, now if it was flat ground and had a hole in the blade i'd carry it more. Oh and lets not forget the famous Spyder :-) Ron

Joe Talmadge
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Postby Joe Talmadge » Sun Sep 08, 2002 10:53 am

M-2 is a high-speed tool steel (that means it keeps its hardness at high heat levels) -- it's used, among other things, to cut other metals.

It is not stainless, and that is M-2's biggest weakness. Benchmade covers it with a coating to prevent rusting. For me, I dislike what the coatings do to the aesthetics.

M-2 has great wear resistance, probably better than all but the CPM steels. It's primary advantage over stainless steels is that it's much tougher than steels like VG-10, ATS-34, etc., and can be hardened beyond what those steels can do. So for a light-to-medium duty knife, M-2 will outperform virtually any stainless steel (M-2 isn't tough enough to use as a hard-use chopper), provided you can deal with coatings or doing maintenance so it won't rust.

However, the introduction of steels like S30V change the equation. S30V is stainless, more wear resistant than M-2, and tougher than M-2, though it's left a tad softer (i.e., weaker) than M-2. If S30V lives up to its promise, it will obviate the need to go to tool steels like D-2 and M-2 to get performance beyond what a stainless steel can deliver.

Joe

midget
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Postby midget » Sun Sep 08, 2002 11:19 am

I see. So it rusts, which is understandable. But they coat it with that B-2 stuff and teflon, right?

So what happens when the coating gets scratched off? SOL?

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Postby Rex G » Sun Sep 08, 2002 12:54 pm

All knife steels will rust in the right, or should I say wrong, environment. And, if properly cared for, plain iron will remain shiny. Here on the Gulf Coast, we have to take good care of our blades. A knife that is not kept in a climate-controlled environment must be protected, and monitored on a regular basis. Even in a house, stainless can eventually rust. I use Sentry Solutions on most of my knives, and Break-free CLP on things with wood grips or stocks.

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Postby Joe Talmadge » Sun Sep 08, 2002 3:17 pm

When the coating scratches off, which it does easily, the knife becomes goofy looking.

Beyond that, Benchmade claims that the coating bonds through a few molecules in the steel, so that even with the coating scratched off, it continues to protect. I did some salt-water diving with my very-badly-scratched-up black-coated mini-AFCK, and I never saw any rust on the blade, even big patches where the coating was scratched off, so maybe it's true it soaks in.

Joe

midget
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Postby midget » Sun Sep 08, 2002 4:42 pm

Fair enough then.

Seems to me like using tool steel is kind of unnecessary. Self defeating, one might put it. I mean, you use a knife b/c it's convenient, right? And tool steel maybe b/j you won't have to sharpen as often or what not. That's convenient. Convenient is strapping on your blade every day and then putting it on the floor when you shower to clean it at the end of the week [or month <img src="smile.gif" width=15 height=15 align=middle border=0>]. Putting break free on the blade every night and keeping it in a dehumidifier is not convenient.

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Postby Joe Talmadge » Sun Sep 08, 2002 4:47 pm

Well, with Benchmade's coating, you don't have to worry about the maintenance. Best of all worlds, in theory, if you can put up with the coating.

I think whether or not it's worth it to use non-stainless steels is a personal decision. Most people prefer stainless for folders, and even fixed-blades -- that's why most knives are made from stainless. But anyone who is after performance will usually be looking at carbon, alloy, or tool steels. And really, giving a quick wipe with tuff-cloth isn't that much of a hardship to me, not for the performance that's to be gained.

All that said, I do think that if S30V plays out as promised, there won't be much of a reason to use non-stainless for performance reasons <i>for EDC folders </i> . There'll still be plenty of reasons to use non-stainless for many types of fixed blades.

Joe

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Postby midget » Sun Sep 08, 2002 5:09 pm

That was quick. You're a cool guy, Joe.

I'm curious. I'm going to get a tool steel blade and see whats up.

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Postby java » Sun Sep 08, 2002 6:07 pm

Joe,

You are truly a compendium of metallurgical fact – our own “Man of Steel”. Your posts are usually so technically precise and structured the following caught me off guard:

“When the coating scratches off, which it does easily, the knife becomes goofy looking."

Goofy looking – is that a technical term? <img src="wink.gif" width=15 height=15 align=middle border=0>

Just kidding, Joe but I did have a concern about M2 as a blade steel.

I know that original high speed steels used up to 18% tungsten in the matrix and as the availability of tungsten decreased during WWII, molybdenum was used as a partial substitute. Its subsequent performance made it common in steels that require hot hardness, high hardenability, and wear resistance. I have heard that M2 is very stressed, brittle, and dimensionally unstable after heat treating and is sometimes tempered TWICE to compensate and achieve the higher hardness levels. With its lower chromium content and propensity to rust (and the use of coatings that wear) is there any concern about using M2 in food preparation or other applications where it can be exposed to citric or other common mild acids?

Stay safe! Stay sharp! <img src="spyder.gif" width=15 height=15 align=middle border=0>

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Postby Joe Talmadge » Sun Sep 08, 2002 10:25 pm

java,

Are you sure "goofy looking" isn't a technical term? <img src="smile.gif" width=15 height=15 align=middle border=0>

I haven't done a lot of experimenting with using non-stainless steels in the kitchen, and I'm reluctant to speak too authoritatively when I haven't done the testing myself. But, from what I hear, stainless really does work better in the kitchen if you're going to be cutting for long periods, because acidic foods can start micro-rusting the edge of a non-stainless blade pretty quick. Professional chefs can see the effect, but I'm not sure if you'd see it in a typical home kitchen, where you tend to be done with the whole job in less than an hour.

Joe

PS to midget: good for you, you'll like M-2. Remember our motto: a steel will never "be all it can be" if you don't let it show its performance in your sharpening plan. After you're done playing with the knife from the box, consider taking the edge down a few degrees. M-2 has better wear resistance than 154-CM, but its real beauty is that it is stronger <i>and </i> tougher than 154-CM, as Benchmade heat treats it. You'll see the true performance of M-2 when you take the edge down a few degrees from where you're comfortable with 154-CM, and see that the M-2's edge still doesn't chip, doesn't roll, doesn't indent, and cuts effectively for longer. Don't look for some kind of supernatural performance, but do expect to see a noticeable bump.

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Postby Philip357 » Mon Sep 09, 2002 6:51 am

"Goofy looking" can probably be considered technical if one is talking about a orangy-long-eared Disney (tm I guess) animal <img src="wink.gif" width=15 height=15 align=middle border=0> .

Joe, or anybody else, what will the price effect be when S30V is used ? Compared to Gin1, 440C, VG10 which Spyderco uses (used ?) a lot or compared to BG42 (is this still a "hot" steel ?) ? Thanks.

Philip

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java
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Postby java » Mon Sep 09, 2002 7:46 am

Joe,

I stand corrected by the International Society of Professional Disnologists and have added goofy-looking to my techno jargon dictionary <img src="smile.gif" width=15 height=15 align=middle border=0>!

That's kind of what I felt about the "micro rusting" but I wasn't sure what effect the coating would have. If what BM says about bonding at the molecular level is true then I guess there should be no worries. I wonder, however, what effect the bnding has on the steel's edge retention. I am aware that some coatings actually increase the RC but I have seen where there is often a concern about breaking through the coating and having minor pitting or, I think the term is galvanic, corrosion set in beneath the coating.


Phillip357,

I don't have the performance characteristics and alloy contents of BG42 on hand. I do know that it, as well as other steels like ATS-34, 154CM, and 52100, were initially deveoped for use as ball bearing steels and found their way into the knifemaking industry. I have heard that 154CM has performance characteristics of M-2 and F-2 which are used as high speed performance cutting steels. M2 is a "hot" steel but I will have to defer any further deduction on BG42 to Joe.

Crucible Materials Corp.'s S30V is the first steel specifically developed for knife blades. It is not designed to replace the high dollar super steels like CPM S60V, CPM S90V, or CPM 10V but can be used in place of popular knife maker steels like ATS-34, 154CM, BG-42, or even D-2. It's still a new steel. General acceptance by the knife-making industry will be determined by performance data and availability. IMO, the pricepoint for S30V is not stable yet but based on the steels it may replace, if performance is similar I would expect a similar or marginally higher price.

VG-10, interestingly enough, was developed in Japan for use in horticulture knives, so I guess one could argue that S30V is the second steel developed for blade making.

Joe???

Stay safe! Stay sharp! <img src="spyder.gif" width=15 height=15 align=middle border=0>

Found some current prices from one supplier for a relative illustration of the same size blank:


ATS-34 3/32 X 2 X 72 $52.37
440C 3/32 X 2 X 72 $40.95
154CM 3/32 X 2 X 72 $57.07
S30V 3/32 X 2 X 72 $84.48
S60V 3/32 X 2 X 72 $105.60
S90V 3/32 X 2 X 72 $107.10


Edited by - java on 9/9/2002 8:01:56 AM

Edited by - java on 9/9/2002 6:18:24 PM

midget
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Postby midget » Sat Sep 14, 2002 11:47 am

just a followup.

literally just got my nimravus today. looks pretty cool.
this tool steel seems like pretty cool stuff. it's sharp.

ill let you guys know how it holds up.

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sal
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Postby sal » Sun Sep 15, 2002 4:40 pm

Hi Midget, This is a learning place where knowledge and opinions are shared.

From a cost point of view, the tool steels are always attractive. A steel like D-2 or M-2 could run one fourth to one third the cost of an exotic steel like CPM-S30V. But as Joe said, Stainless seems to be preferred by most knife buyers.

Regarding steels that were developed for knife use, there are a few.

ATS-34 was developed by Hitachi to replace the discontinued 154-CM, which, at the time was only being used for custom knives. So technically, it was developed as a knife steel.

Gingami I ("silver paper" in Japanese) was developed as a knife steel and was Spyderco's primary steel until the more exotic steels were developed.

ATS-55 was developed as a knife steel.

As mentioned, VG-10 and CPM-S30V.

I believe the Japanese OU-31 was developed as a knife steel, but to date, there are no production knives using this steel.

Damasteel was developed primarily to be used in knives. Michael Walker is the US importer of this powdered damascus.

There are a host of "old" steels that were developed for knives/swords: Wootz, Viking Damascus (800-1200 AD), Samarai sword steels, etc.

I'm sure that I'm missing some, but knives are more "special" than one might think.

sal

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Postby Knife Knut » Sun Sep 15, 2002 9:45 pm

If Spyderco Knives came in tool steels, I would buy them.

Knife Knut on a shoestring budget.


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