Pro VS Amateur Heat treating?

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I don't like breaking knives after I've invested tons of time in the making. Learning how to let go and just beat the snot out of a blade so you can see how your heat treat is.... ugh! I know it's necessary, but I hate every bit of it.

Even if you aren't selling or making knives by the dozen, it's still a good idea to send it out to the pros. Ten bucks, plus shipping, isn't going to break the bank, in my opinion, but it sure does make me feel better when I'm using that knife or give it away as a present.
 
I think what I'm gonna do is send out the ones that come out really nice - grind, plunge, design, profile - and keep on doing any that don't come off the grinder as nice myself. That way I get to keep learning how to heat treat, but at the same time I should be able to produce some decent work with a reliable heat treat from a reputable shop.

I'd like to thank everyone for their input.
 
I often caution new makers from buying all sorts of high end equipment when they don't know how to make a knife yet. All that is needed to make a good knife is a file, some sandpaper, and lots of time and effort. Once you can make a good knife with those, you can then refine those skills with better equipment.

What great advice thank you!
I was getting to wrapped up in equipment without building my first knife yet. Bought some files sandpaper and a small grinder to get started using a skill saw blade to start. Baby steps!
 
Bev66 said:
I often caution new makers from buying all sorts of high end equipment when they don't know how to make a knife yet. All that is needed to make a good knife is a file, some sandpaper, and lots of time and effort. Once you can make a good knife with those, you can then refine those skills with better equipment.

What great advice thank you!
I was getting to wrapped up in equipment without building my first knife yet. Bought some files sandpaper and a small grinder to get started using a skill saw blade to start. Baby steps!
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Very bad idea. Get a bar of 1084 or other blade steel. Most likely the skill saw is not blade steel. If you use an unknown steel, how will you have it heat treated?
 
Thanks Stacey

This one is to learn how to cut and grind, not going to heat treat this one at all.
Spent a few hours on it today and it was great fun but happy it's a learner blade, screwed up a few times with angles.

Have an order in for 1084, looking forward to it!
 
The initial posting raised an issue that I have been curious about myself that I was hoping would be addressed. In the initial question one blade was brought to Rockwell 63 after quench and then tempered to 57 and the second blade was brought to Rockwell 59 and then also tempered to 57.

I have always wondered what the effects on grain structure and performance are when the same final hardness is achieved by using higher and lower Austenitize temperatures and then compensating with tempering temperatures to achieve the same final hardness. From my limited knowledge I understand higher Austenitizing temperatures promote grain growth as does longer soak times so I would assume it would be desirable to use as low a Austenitizing temp that will get one to the desired hardness but I understand I could be completely and totally wrong which is why I’m asking, LOL.

I asked this question because often multiple Austenitizing temperatures are recommended in datasheets and I wonder the consequences of using higher or lower. This chart is from Crucible for CPM-154. As you can see if one wanted a reading of Rockwell 60 one could achieve it by either Austenitizing at 2000°F and tempering at 600°F or Austenitizing at 1900°F and tempering at 400°F.


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Assuming the same equipment and techniques were used other than the different Austenitizing and tempering temperatures to achieve the same final hardness my question is what would be the difference in grain structure or size and how would that differentiate itself in performance if any.

And if anybody would like to comment further if one were using a stock removal method and for the sake of continuity on CPM–154 what would also be the optimal total heat treatment regiment? I ask this because I have heard a lot about things like grain refinement steps, heat cycling, normalizing and multiple quenching to improve grain structure and size and I wonder if that improves performance when doing stock removal or only with forging?

I find myself fascinated by the whole process of heat treating and I won't send knives out to be professionally heat-treated because I feel mastering heat treating is a major part of knife making and I would rather make some subpar knives along the way and have sole proprietorship of my craft with the goal of eventually being a competent heat treater. Obviously that is just my approach and I respect those who differ.

I have taken Stacy’s advice on starting simple and buying better equipment as one understands what is really needed and I know my next purchase despite the cost has to be a Rockwell hardness tester because without it I am assuming I am getting the results I am after but I don’t really know. Also after that I will be getting a real programmable oven.
 
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Jeff, great questions. Austentizing temperature and tempering temperature are chosen depending on what properties the heat treater is trying to maximize in their steel. By varying aust temp and tempering temps, one may arrive at identical HRC values, but the microstructure, depending on what you did, will be different. Grain size, carbide fraction, and carbide size can be affected. There is a graph each steel has, wear resistance vs toughness. Usually these intersect at a certain HRC value. Deviating from that HRC value may cause problems. For example, I hear that Elmax performance is spot on at 60-61. I hear S35VN is spot on at 59.5-60.5. By raising aust temperature, you can increase wear resistance, at the cost of toughness. Same with tempering....too high a temperature and you lose performance, too low and you have chipping issues.

I think your question would then be, "Ok so Elmax is best at 60.5, let's say. There are a few ways to arrive at that 60.5, maybe by varying aust temp and tempering temp. So which is best?" And I think the answer depends on the properties you want maximized in the steel. Wear resistance? Impact resistance? Bend resistance? To balance all of these, to me, is the goal. But some may want to sacrifice some wear resistance for impact resistance, etc. Just depends on what you want to do.

May I refer you to "HEAT TREATMENT EFFECTS ON CPM-M4 TOOL STEEL PERFORMANCE AS EDGED BLADE MATERIAL" by Sid iLian Very good reading material for your question.
 
Thank you samuraistuart for that excellent article. You definitely pulled out a gem with that one because it addressed in great detail exactly my questions.

I am not going to pretend I understood all his explanations as to the processes of how M4 was changed with different austenitizing and tempering temperatures because being a Masters thesis I wasn’t familiar with all his terminology but his graphs especially the last one certainly made it abundantly clear what the end results were of the different temperatures which was exactly what I was hoping to find out.

And what I really appreciate is that it being a Masters thesis I know it is based in science and not just someone’s opinion. I have downloaded it and I will definitely be giving it many more reads in the future trying to decipher further how and why the changes occurred and not just what the end results were.

What I found most surprising was that “the hardness results have no clear relationship with the carbides fraction or size, which also confirms that the softening of martensite matrix will determine the hardness of the final product.” “Similarly, there is no clear relationships between edge retention and other measurements of carbides phase, such as carbide size, count and interparticle spacing.” ”After comparing to other edge blade performance measurements, the edge retention performance only relates to the hardness results.” I found this very surprising that edge retention is only related to hardness of the matrix and the carbides only have to do with toughness and strength.

With the info I gained from the article I feel I can dial in my heat treating better for specific applications which is exactly what I was hoping for so again thank you samuraistuart for the excellent reference material and thank you Dave for starting this thread which led to this great information.
 
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I read this paper a while ago. It has good experiment data however conclusion on edge retention is unsupported because carbide fraction variable has low correlation/weighted-coef in statistical/finite-element analysis. Carbide fraction low variability due to predominated MC and high delta of martensite/RA/various-precip+diffuse_carbides. Therefore very little conclusion should be drawn from this set of experimental data.

For high % (above 3%) of Cr+Mo, I often refer to this computational thermodynamic model - http://www.calphad.com/AEB-L.html. Surprisingly applicable to most PM steels, of course moving the temperature line up/down a little bit depend on Mo and other elements (Ni, Si, Nb, ...). This model is isothermal, while real ht (with oven) only isothermal after certain amt of soak time. Cooling is mostly about kinetic, where transformation is dynamic, so calculation can be done on iso-temperature step or linear cooling.

A big problem... is producing a targeted/seeked ht result. Sometime, good enough is all you can get with a particular set of equipment. Buy a good+big digital ht oven with gas injection. Better yet get access to a molten silica pot (similar to Peters Ht) for ht - vertical to keep 'em blades straight and virtually decarb free :p

samuraistuart said:
Well, glad I could be of some help anyway! I do like that article on M4. Really helped me wrap my brain around this stuff. Here is a link for others..... http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/54906/LianSidi2015.pdf?sequence=4
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I have been reading your posts bluntcut for a while vacillating between two opinions that you are either a mad genius with superior knowledge and insights or a nut job spewing technobabble to try to sound like someone grandiose and after your posting in this thread I’ve come to the sad conclusion that it is the latter.

In your first paragraph you say the conclusions of the thesis written by Sid Lian to attain a Masters degree in Material Science at Oregon State University which samuraistuart referred me to are unsupported and that very little conclusion should be drawn from this set of experimental data. Despite the woman that approved this thesis is Julie Tucker who has a PhD in nuclear engineering and engineering physics from the University of Wisconsin. Here is the website outlining their qualifications; http://research.engr.oregonstate.edu/nmm/people.

Like most of your posts that paragraph is so saturated with techno-jargon I couldn’t make head nor tails out of it so I won’t dispute your hypothesis instead what I will challenge is your expertise in the field to challenge two such highly educated and qualified people in their fields. Do you have a PhD in material science or in engineering physics and if not where do you get the insights to challenge two such highly qualified individuals?

The next thing I object to in your post which affirms to me your criticism of the thesis is bunk is that after criticizing that thesis as having an unsupported conclusion you offered in its place what you called a computational thermodynamic model which in fact it was simply what the rest of the world calls a phase diagram. How a phase diagram of ABE-L in any way can have any relevance in a discussion about the effects of various tempering and austenitizing temperature combinations discussed in the thesis is absolutely beyond my comprehension. All that diagram could tell you is the maximum and minimum austenitizing temperature for that particular steel and nothing about tempering and their affect which was the whole point of the thesis.

My frustration comes from the fact I spent an evening learning about phase diagrams because of your post thinking it was pertinent and I concluded what one can learn from them I believe is the phase of various metals at various temperatures and the chemical component at each temperature and the weight fraction of each temperature. And how that has anything to do with the thesis you condemned is beyond my comprehension.

If you are in fact a mad genius please explain why I am mistaken regarding how that phase chart can be used with the topic of the thesis that you introduced it to address as if it has some relevancy. I’m not a person that likes confrontation but I think it is pretty pathetic to put out such ridiculous posts and waste people’s time leading them down wild goose chases like you did me with your ridiculous chart.
 
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Again I dispute your assertion bluntcut because we both have something to prove and gain. What I have to prove is that you are a fool spewing technobabble nonsense in a pathetic effort to seem important which wastes people’s time and muddles the conversation. I wish someone had warned me to ignore your ridiculous posts so I am doing that favor to others. I spent an entire day researching your assertions thinking I would learn something and when I realized they were nonsense I was annoyed I wasted the time so I am hoping to spare others the same frustration.

What you could gain is your reputation back by proving that your previous post condemning that thesis and putting up that ridiculous phase diagram have any logical validity. Again I challenge you Sir to explain how that ridiculous phase diagram has anything to do with the Masters thesis you condemned. I will take your silence on the matter as admission that you are a fool because I know your assertions are unsupportable.
 
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Remove MC from whichever high alloy PM or ingot steels, then perhaps you can see how the diagram possibly applicable. Of course MC affects kinetic. For more accuracy (simulation) use JMatPro or similar simulation program, plugging in composition balance (after removing MC). I don't have such prg, so extrapolation is good enough for me.

Good lucks and have fun with metallurgy rabbit hole.
 
My challenge to you bluntcut was not for me to see how the diagram was "possibly" applicable to the thesis you condemned but for you to explain how it was like you asserted it was which obviously you didn’t because it isn’t. Trying to talk to you is like trying to nail Jell-O to a wall and about as productive. I wish you luck also with your metallurgy because I think you will need it but from now on I am going to completely ignore you because I don’t think anything you say is of any value, good luck.
 
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Jeff, if you don't like his answer, either refute it or let it go. Since you aren't refuting it, just complaining about his opinion, I will close this thread.

Bluntcut - Just let it be.

If you two wish to continue this as a gentlemanly metallurgical discussion, I suggest using PM and email.
 
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