Steel testing underway...

[aarongough]

Hey guys!
First post here, but I've posted a reasonable amount to other forums in the past. I'm posting here now because I'm doing some testing on a variety of steels that other people may find informative. Some examples of my past work (just to show I'm not a complete newb ):

http://imgur.com/a/rXsQC
http://imgur.com/a/dNdyB
http://imgur.com/a/bM6Hj

Now, before I start let me just disclaim something: These tests are in no way the last word on these steels!

My sample sizes are too small, and my tests far too subjective for these tests to be authoritative. They're meant to give me a feel for each steel, and to be a good introduction for me to each one. This thread is not meant to start any steel holy wars. If anything I'm putting this stuff out there so that I can learn more from all you experienced folks!

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In the past my knives have been made from O1 that was heat-treated in a small 2 brick forge. I was overall happy with the results but found that I was getting a bit too much edge-rolling with the O1. I figured this was likely because of my heat-treat so I bought a kiln. Once I bought the kiln I realized that there was a whole world of steel out there, and that it was likely something else was better suited to my style of knives!

In order to decide which steel I wanted to use going forward I decided to make a variety of test blades in different steels and then put them through their paces.

The steels I'm testing are:

• O1 (homebrew heat-treat in small forge, for reference to my past knives)
• O1
• A2
• CPM154
• CPM3V
• 440C

The test blades were ground from their respective stock, heat-treated, and then sand-blasted so that they would be as identical as possible. As I did each one I engraved the name of the steel in the handle area of the test blade. The heat treatment recipes were basically whatever the manufacturer recommended:

CPM3V
Preheat to 1500ºF, Equalize
Ramp to 2050ºF, hold for 20 minutes
Quench in air to below 125ºF
Temper at 1000ºF, 3 times, 2 hours each
Aim hardness 61HRC

440C
Preheat to 1425ºF, equalize
Ramp to 1900ºF, hold for 20 minutes
Quench in air to room temperature
Temper at 300ºF, 2 times, 2 hours each
Aim hardness 59HRC

CPM154
Preheat to 1400ºF, equalize
Ramp to 1900ºF, hold for 60 minutes
Quench in oil to below 125ºF
Cryo-quench into dry-ice & isopropanol for 20 minutes
Temper at 400ºF, 2 times, 2 hours each
Aim hardness 60HRC

O1
Preheat to 1250ºF, equalize
Ramp to 1500ºF, hold for 15 minutes
Quench in oil to 150ºF
Temper at 400ºF, 2 hours
Cryo-quench into dry-ice & isopropanol for 20 minutes
Temper at 400ºF, 2 hours
Aim hardness 61HRC

A2
Preheat to 1100ºF, equalize
Ramp to 1775ºF, hold for 35 minutes
Quench in air to below 150ºF
Temper at 400ºF, 2 hours
Cryo-quench into dry-ice & isopropanol for 20 minutes
Temper at 400ºF, 2 hours
Aim hardness 61HRC

The O1 that received the 'homebrew' heat-treat was basically heated in a propane fired forge until dull cherry red, then quenched in oil. It was then tempered twice at 400ºF, two hours each time.

CPM-3V moments after leaving the kiln

After all the blades were finished the next step was to ensure that the edge thickness of each blank was as identical as possible. The edge thickness I was aiming for was 0.013". All the blanks ended up being a maximum of 0.0005" away from this thickness. This was achieved by grinding each blade a little thin, then using a diamond hone along the edge of the blank until the edge was the correct thickness.

** Be aware that my test blades are a little sloppy around the plunges and such. I only just got a grinder and these are the first knives I've made using a grinder rather than filing by hand.

 

[aarongough]

After the test blades were all completed I wrapped the handle area of each blank in tape so that the identifying engraving was hidden. This way I can ensure that I can test each blade without having a preconceived notion of how it should perform, as I literally don't know which blade is which!

The lineup of test blades after their identifying engraving has been taped over.

The knives were then shuffled, and engraved with a number in the ricasso area, this is the identification number for each blank. This allows me to track the performance of each blank across the tests without having to know which blank is made from which steel.

Now finally, the first test can begin!

Sharpening time test:

The first thing I wanted to check for was ease of sharpening. I basically did this by taking each blank, which is identically shaped, and has identical edge thickness, and sharpening it up using the exact same technique and timing how long it takes. Not exactly super scientific, but it gives me a bit of a feel for each steel.

I used a Lansky diamond deluxe sharpening system for the test. Each blade was sharpened to 600 grit, then stropped. Stropping time was not included in the test results.

[FONT=Courier New]
Blade         Time	  Notes
1	      9:08  	  Slightly snaggy, toothy, edge before strop. Still kinda toothy after strop.
2	      7:19	  Shaving sharp even without strop. Really sharp after strop, push cuts nicely.
3	      8:23	  Not really push cutting before strop. Really sharp & great push cutting after strop.
4	      6:21	  Push cutting a bit before strop. About the same after the strop.
5	      6:49	  No push cutting before strop. Push cutting a little after strop.
6	      6:51	  A bit snaggy before strop. Push cuts ok after strop, still a little snaggy.
[/FONT]

Sharpening the test blades with a Lansky sharpener

In my eyes steel #2 was the winner in this test. The edge was noticeably sharper than the other even without stropping. The difference in sharpening time between the steels wasn't really enough to put me off any of them. As I was sharpening for the first time I was removing quite a lot of steel, and it was all still relatively quick.

If one of them had taken 15 minutes or something then I would have known that steel would have been significantly harder for my customers to sharpen.

NOTE: If you guys have suggestions about testing methodologies I'll be happy to hear them for future use!

 

[aarongough]

Fine edge retention test:

This test was intended to see how long each type of steel would retain it's finest cutting edge under relatively normal usage conditions. To test this I sharpened and stropped each knife until I couldn't tell them apart for initial sharpness, then cut sisal rope with each one until it would no longer cleanly slice phonebook paper.

Because this test involved a relatively subjective measurement process I repeated the test numerous times to get a larger sample. Each time I covered the identification number of each blade so that I wouldn't be able to associate a certain blank with an expected level of performance. Every run was done 'blind' in that I didn't know which knife I was using at any given time.

The test was done using only a 1" section of each blade. This was achieved by taping up the blade so that only a 1" section was exposed, then making sure to stay within that section.

Testing the edge after making a series of cuts

For each knife I would make 20 cuts, then test the edge. If it still cut the paper cleanly I would make another 20 cuts and so on...

[FONT=Courier New]
Blade   Run 1   Run 2   Run 3   Run 4       Avg     Deviation
1       11      4       5       7           6.75    3.10
2       6       7       6       4           5.75    1.26
3       8       8       9       4           7.25    2.22
4       6       4       5       11          6.50    3.11
5       5       6       3       7           5.25    1.71
6       2       1       1       3           1.75    0.96
[/FONT]

The tests were somewhat noisy, so I calculated the standard deviation for each test run, then removed any results that were more than 1 standard deviation away from the main group of test numbers:

[FONT=Courier New]
Blade   Run 1   Run 2   Run 3   Run 4       Avg   Deviation
1               4       5       7           5.33  1.53
2       6       7       6                   6.33  0.58
3       8       8       9                   8.33  0.58
4       6       4       5                   5.00  1.00
5       5       6               7           6.00  1.00
6       2       1       1       3           1.75  0.96
[/FONT]

This gave me the final results:

[FONT=Courier New]
Blade    Avg   
1        106 cuts 
2        126 cuts  
3        166 cuts  
4        100 cuts  
5        120 cuts  
6        35 cuts   
[/FONT]

IMPORTANT EDIT: This data is somewhat noisy, so be wary of drawing exact conclusions from it. Probably the best interpretation is: all these blades held an edge acceptably, except for #6

Blade #3 is obviously the winner here by a significant margin. Blade #6 failed this test miserably!

I made 2660 cuts in total, and had quite bad blisters on my hands by the time I was finished!

To be clear: by the time a blade was 'failing' this test and was starting to snag the phonebook paper, it was still easily capable of shaving hair. This test was testing the retention of the very finest edge!

 

[aarongough]

For some reason I'm having trouble posting to the thread now... I can't seem to post the rest of the results, but short posts obviously work ok...

 

[Frank Niro]

You've done a lot of work there ! I'm going to review it carefully although my main use is in Damascus steels made by others. Have you checked out "knife Reviews and Testing" in this forum? Mr. Ankerson has done a terrific job in bringing forward information on blade steels. Frank

 

[fadugleman]

Awesome

 

[aarongough]

You've done a lot of work there ! I'm going to review it carefully although my main use is in Damascus steels made by others. Have you checked out "knife Reviews and Testing" in this forum? Mr. Ankerson has done a terrific job in bringing forward information on blade steels. Frank

I spent a lot of time on this forum and others during the research process that led up to the steel selection for the test. People like Ankerson have really done us a great service with all the info that's out there! Looking over all the charts and such that are out there is what made me select the steels I did.

The main purpose of the testing was for me to really get hands on with a bunch of different potential steels and see how they came up after heat-treating in my shop, what was involved in each one, etc... Personally I have high hopes for CPM154, but we will have to see which steel comes out of the testing as a winner! I don't really expect to discover anything new and amazing, but it's a great experience to work with a bunch of different steels in such a short period of time!

 

[aarongough]

Thanks very much mate!

 

[Don Nguyen]

Hey Aaron, nice to see your work progressing. I'll have to go through this after classes, but it looks like youve got some good stuff going on!

 

[aarongough]

Hey Aaron, nice to see your work progressing. I'll have to go through this after classes, but it looks like youve got some good stuff going on!

Hey Don! I figured you would chime in at some point!

I haven't quite gotten used to the grinder yet, but it's very nice to have it! I'm looking forward to feeling comfortable about making nice bevels on it!

 

[Huntsman Knife Co.]

Very cool! I will be watching this one closely. I'd love to do a test like this but with ELMAX, m390, 3V 4V and M4. My hands will be sore when that day comes!

 

[aarongough]

Very cool! I will be watching this one closely. I'd love to do a test like this but with ELMAX, m390, 3V 4V and M4. My hands will be sore when that day comes!

Haha, yes that sounds like it would be quite the test! I would like to try some of the other really high-end steels at some point too, though I think that realistically something like CPM154 is likely about as far as I want to go in terms of wear resistance...

 

[leifjl]

Very methodical approach.
I'm looking forward to seeing the results.
Thanks for sharing this with everyone.

 

[Frank Niro]

Well, perhaps before Elmax and M390 in the stainless and CarbonV CPM154 might have been the one to go with for wearability, grinding, sharpening etc. but my thoughts at this point are it's only as popular as it is because there isn't much choice in sizes at this time. Hey, I still believe the CPM154 to be a terribly good steel.
I believe you will see lots of action on this topic and your introduction into it again. There will be many that will tell you the only steel to use is the one they themselves are so pleased with . You won't help them to consider to try something else but so what. This is a great place to have and talk about such differences. Frank

 

[Daniel Fairly Knives]

Awesome job and welcome to Bladeforums!

 

[Tom Lewis]

Lots of great information here. When are you going to tell us which steel is # 1-6?
One suggestion I would make is to have each blade RC tested. It could be the poor performing blade does not have the proper RC hardness.
Thanks for a very informative post.

 

[Hankins]

Wow thanks for all the hard work! Right up there with glue wars:thumbup:

 

[aarongough]

I've been having a lot of trouble posting today guys, I've been trying to post the rest of the results but the posts won't go up... I'm waiting for that situation to be resolved before I can continue.

 

[aarongough]

Wow thanks for all the hard work! Right up there with glue wars:thumbup:

No worries! I benefited greatly from the 'glue wars'! Because of that thread I now sandblast all my glue surfaces, and my knives are better for it. I hope that my thread helps some people in a similar way!

 

[aarongough]

Lots of great information here. When are you going to tell us which steel is # 1-6?
One suggestion I would make is to have each blade RC tested. It could be the poor performing blade does not have the proper RC hardness.
Thanks for a very informative post.

Even I don't know which steels are #1-6 yet! You shouldn't have to wait too long though, a day or two at the most.

I think getting the blades rockwell tested is a good idea! I have a set of hardness files here, but they're not good for much to be honest. I'll have a look around my area and see who I can find that might be able to do the testing.