13 Myths about Heat Treating Knives

[Larrin]

A new article about various heat treating myths, covering things like the effect of heat treatment on knife performance, whether industry heat treatments are relative to knives, cryogenic processing, and heat treating simple carbon steels vs high alloy and stainless steels. https://knifesteelnerds.com/2020/07/13/ ... ng-knives/

[Pancake]

Great article as always.
I have one question regarding number 2. ,,Backyard bladesmith discovered a new super heat treatment that can’t be matched,,

I think you know about one blade forum member BluntCut (I think he is also here) and his crystal weaving foundation heat treat (or something like that). What are your thoughts on that? He claimed that he could HT some steel higher then anybody else on the planet (well, maybe not these exact words but close) and his HT include some swirling and slicing in quench oil to get the microstructure.

[Mike Blue]

Thanks for the great morning read with coffee, Larrin. Another well done article, woven together with several others of like quality.

My first question: What is the effect of carbon content on retained austenite? My belief suggests that unless the carbon content is over the eutectic point, and other carbide formers, there isn't enough there to have any retained austenite given a "good, by-the-book" heat treatment. Your graphics suggest that all steels have retained austenite in some form despite chemistry. Maybe expand on that thought a little from your experience.

[Wartstein]

Once again: Thanks, Larrin, for sharing your knowledge with us.
I am really looking forward to reading this article when I come home and can take my time for it. :)

[Larrin]

Great article as always.
I have one question regarding number 2. ,,Backyard bladesmith discovered a new super heat treatment that can’t be matched,,

I think you know about one blade forum member BluntCut (I think he is also here) and his crystal weaving foundation heat treat (or something like that). What are your thoughts on that? He claimed that he could HT some steel higher then anybody else on the planet (well, maybe not these exact words but close) and his HT include some swirling and slicing in quench oil to get the microstructure.

I argued with Bluntcut a significant amount in his giant bladeforums thread and I'm not particularly interested in talking about it anymore.

[Larrin]

Thanks for the great morning read with coffee, Larrin. Another well done article, woven together with several others of like quality.

My first question: What is the effect of carbon content on retained austenite? My belief suggests that unless the carbon content is over the eutectic point, and other carbide formers, there isn't enough there to have any retained austenite given a "good, by-the-book" heat treatment. Your graphics suggest that all steels have retained austenite in some form despite chemistry. Maybe expand on that thought a little from your experience.

Carbon is the most significant element for retained austenite. Eutectoid (eutectic is different) in a simple iron-carbon steel is around 0.78% and with basic Mn/Si alloying is down to around 0.75%. Retained austenite shows up with a simple full austenitize and quench somewhere around 0.5% carbon. That assumes no other alloying elements and no modifications to heat treatment. For example, professionally I develop automotive steels that are designed specifically for maximizing retained austenite content and we don't make anything anywhere near 0.5% carbon. Most alloying elements decrease martensite formation temperatures and increase retained austenite. Almost all of the common knife steels will have at least a small amount of retained austenite. The cryo article I linked to in the post has more information on the effect of composition.

[Ankerson]

Excellent article. :cool:

I and a few others have been trying to tell people those things for a long time.......

Usually falling on deaf ears.....

Myths and urban legends die hard.... :rolleyes:

Those things are the reason I got into testing in the 1st place....

[Mike Blue]

Thanks Larrin.

[Pancake]

I argued with Bluntcut a significant amount in his giant bladeforums thread and I'm not particularly interested in talking about it anymore.

I complete understand Larrin.

[JD Spydo]

Another great article and I really appreciate your contributions here on the Forum Brother LARRIN. It just goes to show you that there are a lot of contributing factors involved in making a premium piece of cutlery>> of any genre.

I've often wondered at times if heat treatment and cryo-quenching actually have more to do with the making of a premium blade than the different alloys do? Oh I know some are better than others no doubt.

I'm also still on the fence concerning some of these newer Nitrogen based blade steels. So far it looks promising

[AlexRus]

A new article about various heat treating myths, covering things like the effect of heat treatment on knife performance, whether industry heat treatments are relative to knives, cryogenic processing, and heat treating simple carbon steels vs high alloy and stainless steels. https://knifesteelnerds.com/2020/07/13/ ... ng-knives/

Thank you! Very interesting!

[Naperville]

I liked your article Larrin. I have an unrelated idea for you and your CATRA machine.

On Facebook in the Vehement Syndicate there is a discussion regarding serrated blades. You do not have to go looking for the article, but you could settle the raging debate on serrated blades.

- Are serrated blades better at cutting card stock than plain edged blades
- Of the serrated blades available, which type of serrations are the best

[ABX2011]

NIce article and well written as always.

[ChrisinHove]

Excellent article. Thank you!

Disappointingly, no mention of incantations and enchantments...

[Larrin]

I liked your article Larrin. I have an unrelated idea for you and your CATRA machine.

On Facebook in the Vehement Syndicate there is a discussion regarding serrated blades. You do not have to go looking for the article, but you could settle the raging debate on serrated blades.

- Are serrated blades better at cutting card stock than plain edged blades
- Of the serrated blades available, which type of serrations are the best

Serrated edges have poorer cutting ability but superior edge retention when slicing.

Edit: data is here - https://knifesteelnerds.com/2018/11/26/ ... etention2/

[Naperville]

I liked your article Larrin. I have an unrelated idea for you and your CATRA machine.

On Facebook in the Vehement Syndicate there is a discussion regarding serrated blades. You do not have to go looking for the article, but you could settle the raging debate on serrated blades.

- Are serrated blades better at cutting card stock than plain edged blades
- Of the serrated blades available, which type of serrations are the best

Serrated edges have poorer cutting ability but superior edge retention when slicing.

Edit: data is here - https://knifesteelnerds.com/2018/11/26/ ... etention2/

Thank you!

[Wartstein]

Serrated edges have poorer cutting ability but superior edge retention when slicing.

Edit: data is here - https://knifesteelnerds.com/2018/11/26/ ... etention2/

Larrin, " serrated edges having poorer cutting ability when slicing" is so contrary to my (admittedly total layman and non scientific!!) in-use-findings, that I may ask:
Could it be that I find Spydercos serrated edges to be even better slicers than their plain edges not because they are serrated, but because SE is ground to a much acuter angle (due to the chisel grind)?

[Cambertree]

Thanks for the excellent rundown, Larrin.

[ykspydiefan]

Thank you Larrin. Having access to understandable knowledge like this is really incredible. Knowledge is cool.

[Enactive]

Excellent article. Thank you!

Disappointingly, no mention of incantations and enchantments...

Haha haha

Totally!