Ultra high carbon simple mono steel

[BluntCut MetalWorks]

Stacy,

I feel honor & great gratitude for your fatherly wise advices. Your wisdom & knowledge are invaluable and generously given - thereby my sincere appreciation. Funny, how I told my kids in similar fashion about the easy way to attain wisdom in life by listen to those already earned them rather than bricks to the forehead ways. From my limited knowledge experience, I agree & concur with your advices. At the same time, I would forward yours recommendation to others.

Worth rephrasing - DO NOT USE SUPERQUENCH unless your end goal is a broken blade - indeed, failure is 99.5% certain. Clearly, I am not and won't recommend anyone to use super quench. But not shy from stating my quench of choice (for now).

My stance is search, not oppose nor irrational justification...

In doing research, I'll take a few bricks to the head - oops sometime brain falls out from a cracked-skull I have Park50 & McCarMaster 11secs oil, they are smelly, although P50 is not as bad. My latest edge litmus test without touchup between step - put a dry facial shaving edge, shave; 15 minutes whittle dry oak & hardwood with knots(45 to 60 degrees with grain); 200 linear feet of cut mix cardboard. Good edge if it's still able to cleanly slice newsprint/phonebook after those 3 steps. Thickness behind the edge (at cutting edge bevel shoulder) around 0.01 to 0.015, bevel angle between 24 and 30 inclusive degrees. A bad edge/blade won't take a shaving sharp and almost guarantee edge damage after a couple minutes of whittling or slicing cardboard.

52100 is my baseline steel with most test knives made - so far, probably around 40 knives with diff size/shape/purpose.

I will give you some advice that you can choose to take or leave. Eventually, you will discover it for yourself.

Pick one or two steels and learn them inside out. Using a dozen steels over two years and saying "this is better than that" is fooling yourself. Without dozens to hundreds of blades made with the same steel you don't know much about what is good or not in that steel. Jumping around from steel to steel actually confuses the issue a lot, too. Pick a single steel and learn all you can about it.
Make a single knife style out of that steel a dozen times. Make each knife start to finish and test it before starting to making another.
Secondly....STOP USING SUPERQUENCH. It is a concoction made up for low carbon steels to try and fool you into thinking they can be good knives. A good carbon steel with .60% or higher carbon will be damaged, not improved in using one of these silly quenchant mixes. Trying to make a steel get harder in quench beyond its designed parameters won't improve it any more than turning the thermostat to 50 degrees will make the room cool down faster. With the proper quenchant and the proper methods, a steel will reach its maximum hardness. You can't make it go past that point. For the type of steels you seem to like I would highly recommend you getting five gallons of Parks #50.

If you want good knives it takes four major things:
1) Good steel
2) Good geometry and blade shape to match #1
3) Good HT parameters and temperature control for #1
4) The proper quenchant for #1

Until those are nailed, it won't matter what you do to try and cheat the curve. The only way to nail it is to practice doing it....many times.

 

[Willie71]

Bluntcut, what Rc are you using for the 15n20? At equivalent Rc #'s, it will not outperform 1075 or 1084, but the nickel allows you to push the Rc 3 to 4 points higher at equivalent geometry. I have a friend testing a skinner at Rc62 this fall. At Rc60.5, there was no chipping issues.

Secondly, have you considered going more aggressive on the edge geometry? Maybe 15 to 20. Degree inclusive angles?

 

[BluntCut MetalWorks]

I don't have a Rockwell tester. Only guess 15N20 blades are ~60rc, since they were 375F tempered. They are sharp & super tough, specs: 0.063 thick at spine above heel; 0.007 behind the edge (cutting bevel shoulder). It performs well but for additional wear resistance, it needs more than just extra hardness. For draw-cut (slicing cardboard), carbides density matter.

Bluntcut, what Rc are you using for the 15n20? At equivalent Rc #'s, it will not outperform 1075 or 1084, but the nickel allows you to push the Rc 3 to 4 points higher at equivalent geometry. I have a friend testing a skinner at Rc62 this fall. At Rc60.5, there was no chipping issues.

 

[Willie71]

It would probably be a good idea to get a tester if you are going to be playing with heat treat parameters.

 

[BluntCut MetalWorks]

It would probably be a good idea to get a tester if you are going to be playing with heat treat parameters.

^:thumbup: along with a few more toys, on the high end - a TEM ... hahaha.

 

[Stacy E. Apelt - Bladesmith]

Willie is getting at what I am....you are guessing this and guessing that and calling it research. It isn't how research works! (I was a research chemist back in the late 60", so I am familiar with the subject.).

Settle down and do a HT method that has the research already done. It will take you a year if you are a fast learner to learn to get the max out of that. Changing all sorts of parameters far from the norm is a bad way to do research.

I will give you a great quote - "It is good to think outside of the box. ...after you have fully discovered and understand everything inside the box."

 

[Willie71]

Bluntcut, if you put it in perspective, how much money have you spent on steel you have blown up? In your area you could get a tester used for a couple hundred dollars. Considering you don't really know how well the heat treat worked, you can't draw any definitive conclusions. For example, with the W2 you found poor wear resistance. With your heat treat temps, did you have excessive retained austentite leaving you with low Rc values? Since you heated higher than recommended, you got over 0.85% of the carbon into solution. It will require subzero or cryo to get the retained austentite converted. You may have been testing blades with mid 50s Rc values, which wouldn't have good wear resistance.

What has been recommended to me by someone much more knowledgeable than me (K.C.) is to take coupons, do a normalizing and grain refinement cycle, then test heat treat parameters changing one variable at a time. Test Rc after quench with no tempering. You should see low values on either side of the optimum temperature/time, and a high spot of Rc65/66 or higher, depending on the steel for the steels we use in knife making. For hypereuctoids, that temperature is the one where you get 0.85% carbon in solution, and will result in minimal retained austentite. I am doing this with a bar of W1 that the supplier says has 0.5% carbon. I don't know if that is a misprint, so I will find the "best" temp to heat treat at.

 

[BluntCut MetalWorks]

Stacy & Willie - your thoughtful advices & comments are welcome and appreciated. Excellent valid points when stay inside the box. I don't know what are all inside this box nor its size but I know that, a successful super quenched of high carbon would consider be outside of this box.

How well the end products perform is all really matter, my route took me outside of the box. I almost buy a hardness tester a few months ago but figured out that this type of test is more useful for products ht-ed inside the box. I've posted how I test my blades and some youtube videos(mythotanlong). To be clear, I am not claim that my end products better than high performance blades produced from proven conventional way (inside the box). Those type of comparison jobs best perform by 3rd parties.

 

[stezann]

I don't undersand how measuring the hardness of the heat treatment's products shouldn't be useful to anybody in and out the box...
i'm start wondering if you relay on temperature measurements or consider it too a little too much into the box to be interesting.

 

[Willie71]

I don't have a Rockwell tester. Only guess 15N20 blades are ~60rc, since they were 375F tempered. They are sharp & super tough, specs: 0.063 thick at spine above heel; 0.007 behind the edge (cutting bevel shoulder). It performs well but for additional wear resistance, it needs more than just extra hardness. For draw-cut (slicing cardboard), carbides density matter.

My last question: Are you designing cardboard cutters rather than general purpose knives? This is a serious question, not sarcastic. If cardboard is the intended medium, then steels with high wear resistance makes sense. O1, A2, and D2 are used for this purpose in industry. Heat treat for carbides rather than fine edge for wear resistance.

There have been many PhD metallurgists with equipment we can only dream of who have studied these steels and developed heat treat parameters for specific applications. I'm struggling to see how you will come up with something new that hasn't been figured out yet.

 

[BluntCut MetalWorks]

Hardness is a useful measurement but not high enough on my tinkering priority, hence the word 'more' mentioned above. When/If my research advance to certain point, SEM & TEM nanograph are require to verify my result. Structure type+shape+size, carbide type+shape+size+distribution, atom count+distribution+orientation.

Temperature is primary an energy state driving phase transformation, my conjecture count/rely on certain transformation to taken place. OR - my delusional research based on my metallurgy ignorant - aka playing in my own steamy pile...

I don't undersand how measuring the hardness of the heat treatment's products shouldn't be useful to anybody in and out the box...
i'm start wondering if you relay on temperature measurements or consider it too a little too much into the box to be interesting.

 

[Willie71]

Hardness is a useful measurement but not high enough on my tinkering priority, hence the word 'more' mentioned above. When/If my research advance to certain point, SEM & TEM nanograph are require to verify my result. Structure type+shape+size, carbide type+shape+size+distribution, atom count+distribution+orientation.

Temperature is primary an energy state driving phase transformation, my conjecture count/rely on certain transformation to taken place. OR - my delusional research based on my metallurgy ignorant - aka playing in my own steamy pile...

If you get a chance, attend a lecture by Roman Landes or Kevin Cashen. What you are looking for has already been done. I have seen the micro graphs of many steels after various heat treat procedures, and 2.5 days was barely enough to skim the top of the skim of the surface. I have seem micrographs of 1095 outside of the box heat treat, and it is a mess structurally.

 

[BluntCut MetalWorks]

Good K390 & S110V and other high alloy steels knives have excellent wear resistant for cardboard cutting. Interestingly, my 52100 and 1095 would out cut those high alloy knives.

My intent is to make knife which has these attributes (haha certain I can hear metallurgist's "can't" should only be "trade off"): high toughness; high strength; high edge stability; great wear resistant; super easy to sharpen. Cutlery shape/size/geometry will be design for the bell-curve of intended tasks.

My last question: Are you designing cardboard cutters rather than general purpose knives? This is a serious question, not sarcastic. If cardboard is the intended medium, then steels with high wear resistance makes sense. O1, A2, and D2 are used for this purpose in industry. Heat treat for carbides rather than fine edge for wear resistance.

In recent decade, there were many metallurgy innovations & enhancements. Knowing mind, knows how little its know. Luckily, when I wander to far in delusional realm, my wife would correct/steer me back to reality land with a PhD stick

There have been many PhD metallurgists with equipment we can only dream of who have studied these steels and developed heat treat parameters for specific applications. I'm struggling to see how you will come up with something new that hasn't been figured out yet.

 

[BluntCut MetalWorks]

It definitely would be awesome to attend those lectures - I held those two in my high regard list. SEM graphs are great but TEM graphs complete the 2nd half - hence love to see some TEM nanographs. Indeed, fire-hose knowledge can back-fill or over-turn my limited skills in this area.

I use performance as a way to detect whether steel has sound or mess-up structure in various amplitude/level.

If you get a chance, attend a lecture by Roman Landes or Kevin Cashen. What you are looking for has already been done. I have seen the micro graphs of many steels after various heat treat procedures, and 2.5 days was barely enough to skim the top of the skim of the surface. I have seem micrographs of 1095 outside of the box heat treat, and it is a mess structurally.

 

[stezann]

i wish you luck with your experiments and i'll be very happy when you will display your SEM and TEM graphs or any other presentation form of your achievements
It is a fascinating world i have to admit

cheers

Stefano