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The Newbies Arena Are you new to knife making? Here is all the help you will need.

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  #1  
Old 05-26-2009, 08:48 PM
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CPM154, 154CM, or ATS-34?

I thought I would post this in hopes someone may have insight on an upcomeing blade test that will be done this year at the Western Canadian Knifemakers Symposium. A test will be done on three knives, each useing the listed materials in the title of this post, all ground as exactly as humanly possible, with regards to bevel and profile, all receiving the same HT process, handled the same.

The test proposes to test the theory that a steel such as ATS-34, or 154CM, will outlast/be stronger than CPM154, due to the grain that is imparted in the steel when rolled into barstock. All three knives will be put through cutting tests,and then distructive testing.

The guys proposeing the tests want to push the knives as far as possible to see if there is a noticable difference in the three steels. No sophisticated equiptment is available, or professional metalurgists present. Just good old boys saying "what if we did this..."

Have any of you done or heard of a similar test, or been curious about the same question?


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Old 05-26-2009, 09:03 PM
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Well, if smaller grain is better..., and CPM technology better homogenizes the alloy, thus permitting smaller grain size and fewer weak spots from poor element mixtures...

...my money's on CPM 154.


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Old 05-26-2009, 09:32 PM
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I thought it might be necessary to elaborate on the reason for the test. As I am a fairly green knife maker, most of what "I think I know" comes from reading. as much as I can, from as many reliable sources as I can (this is what I love about this site).

The debate around the water cooler with some of the long time makers I know, argue that because of the lack of any directional stability imparted to the steel in ATS-34 and 154CM, CPM154 with consideration to the superior grain and better blend to the alloy, will still be weaker when pushed further than might be the norm.

I have, because of my reading put a lot more of my faith in the CPM process, but still find myself seeing the other site of the discussion. Being the curious type, and wanting the best for my knives, I couldn't help but try to forsee the outcome of the test, and maybe spark some discussion here.


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Old 05-26-2009, 10:22 PM
AcridSaint AcridSaint is offline
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I don't think that you'll be able to find a significant difference between these knives. If you do, I wouldn't read anything into it because it's only one very small data set. The science behind the steel indicates that the CPM steel will be better, industrial testing seems to confirm it. The test of three blades, each in a different steel won't tell you much of anything. You might get the same results if they were all one steel. Added to this is the fact that the tester is going into this trying to prove their belief, hopefully they won't know which knife is which steel.


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Old 05-27-2009, 12:07 AM
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I agree with Cap. When you conduct the test with the aim of proving a point, the tester will always seem to do so.

I like the 'good ol' boy' approach, but I fear that it'll be less than scientific.


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Old 05-27-2009, 07:03 AM
argel55 argel55 is offline
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Andy I'm with you on steel selection. I would think from what I have read is that the CPM154 will have twice the lateral strength than the 154CM or ATS 34. Just my memory. I know the CPM finishes a lot easier and cleaner than the other two. One problem will also be that the ATS34 is not as clean a material as it was when first introduced. That may make the test even more different.
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Old 05-27-2009, 08:46 AM
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I agree with all the above, especially that ATS34 isn't the same as it used to be. I second the opinion that the tester must not know which steel is which while the test is being done.

Further, I will say that although those steels are very much alike in composition using the same heat treat for them will skew the test. The same heat treatment will produce adequate blades from each steel but not necessarily the optimum blade from each steel. For instance, leaving out a cryo step will affect the steels differently (the CPM steels seem to benefit greatly from cryo) and a quenching temperature that differs by 50 degrees may benefit one steel or the other. So, unless the heat treatment is tweaked to produce the optimal blade from each steel all you might prove is that ATS34 or 154CM can out perform CPM154 when the heat treatment has been crippled ......


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Old 05-27-2009, 11:43 AM
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Quote:
Originally Posted by Bear_Blade
No sophisticated equiptment is available, or professional metalurgists present. Just good old boys saying "what if we did this..."
I think what Ray described is exactly what will happen when the above is done.

David


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Old 05-27-2009, 12:53 PM
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Thanks for the input guys, and in the interest of fairness, I called the guys proposeing the test. The knives will be made by one maker, HT done to acheive the optimum performance for each steel, (not sure about the cryo) the knives will be stamped with steel type below the handle, other atending members will perform the test, unaware of which knif is made from which steel, and only after the knives fail, will the handles be removed to reveal the winner. It isn't scientific, but I think that imparts a little more fairness to the test, I'm going to try to talk the maker into doing the cryo on the CPM154. Any other suggestions or comments to make this test more fair, or comments positive or negative are welcome.

EDIT- the question was posed to the guy making the knife, he is questioning the need of the cryo if the HT is done in a salt bath verses an electric oven, stateing the cryo process will only help if the HT was done in an electric oven, in foil. he says that the temp can't be lowered quickly enough to acheive the best conversion of austenite to martensite, compared to a salt HT and salt quench.
He had knives tested at the UofA and found an edge hardness of two to three points lover than the spine, of oven treated blades. Knives were quenched in the fiol pouch useing plates, as well as oil.
This is above by complete understanding, but any advice or tips will be passed along, and the test adjusted if it will make it mor fair to each of the steels being used.


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Last edited by Bear_Blade; 05-27-2009 at 02:48 PM.
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  #10  
Old 05-27-2009, 09:41 PM
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What Ray said, but.....Samples of one will prove precious little.

-Mike-


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  #11  
Old 05-28-2009, 03:33 PM
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You forgot one - RWL-34 a powder metal type.
Chemically they are the same but 154CM and ATS-34 are conventionally melted while CPM154 and the European RWL-34 are powder metal types.There have been changes in 154CM and ATS-34 as far as melting practices and quality [inclusions etc ], over the years.
CPM154 and RWL-34 are inherently cleaner with finer and with more uniformly distributed carbides. This means higher toughness especially transverse.Also easier to grind and polish ,easier to sharpen yet have better wear resistance .
CPM154 has become a favorite for makers and users with the only negative a slightly higher price.
But then I'm a metallurgist so stay away from my advice !!
BTW differentiate between finer carbide size and finer grain size - two different things. The CPM version has finer carbides but you could still screw up and make coarse grains !!
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Old 05-29-2009, 08:44 AM
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Mete, care to comment on this?

QUOTE: he is questioning the need of the cryo if the HT is done in a salt bath verses an electric oven, stateing the cryo process will only help if the HT was done in an electric oven


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Old 05-29-2009, 11:25 PM
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Not true ! Cryo deals with retained austenite which is a function of austenitizing temperature .Assuming the same temperatures and times are used the results ,electric or salt, will be the same.
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Old 06-01-2009, 09:29 AM
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Oh boy! I think I may be getting in a little deep, but here goes... Thanks again you guys for posting your comments, I was interested in a simple test, but now find myself with questions on how to do things to the highest level that I can.

Mete: Could you help me understand a little more... "whether salt or oven the result is the same." OK, if I understand correctly, the goal is to convert as much of the austenite to martensite as possible. Is it possible to get the best conversion without a cryo treatment (in salt or oven) of either of the three steels, or does the cryo treatment give enough of a conversion, that a guy should utilize the process as much as possible?

Second, what qualities does the process impart to the steel, be it better edge retention, toughness, or is it just a higher RC number?

Thirdly, if useing an oven, what is the best/fastest way to quench? If useing foil and plates, how do you deal with the airspace near the edge? I have seen test resulte done by the U of A on sample blades plate quenched, showing the spine 2 to 3 points harder than the edge, presumibly because the airspace prevented contact with the plates, and acting as insulation, slowing the quench. If useing a liquid quench, how does a guy get the blade out of the foil and into the quench medium fast enough so as to get the top results?

I appreciate any direction you can lend, and I welcome any and all comments.


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Old 06-01-2009, 11:00 AM
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In science, an important question is the degree to which an inference could be made based on the sample collected.

You are hoping to infer that, in general, one of the several steels you are testing may be demonstrated to be significant over the others, all other things being equal.

However, in order for all other things to be equal you must account for those other variables--oven variability, quench technique, etc., etc.

The only valid inference that you will be able to make is, that among the steels used under the conditions available by this one particular maker, steel X is better.

The reason I mention this is, there is sometimes an urge to go and proclaim findings that are not necessarily valid, given the amount of data available. And a sample size of 1 is not a lot of data. . .
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