Heat Treating Seven Different Steels with a Forge and Magnet

[Larrin]

I tried my hand at heat treating with a forge. I used a range of different low alloy steels and measured each for hardness and toughness to see if I could successfully pull off good properties with little or no experience. I used the information gathered in my previous article/video about the best prior microstructure for forge heat treating.

Article: How to Heat Treat Knife Steel in a Forge - Knife Steel Nerds

Video:

 

[Deadboxhero]

@HumbleHomeCook @Matus @M1k3 @Barmoley



Dr Larrin did a great job on this video, I've time stamped it to a very important concept in the video that is not as well understood as it should be among us knife guys.

There are two main types of martensite which are dependent on heat treatment as to which forms.

One type is more brittle and prone to creating micro cracks during its formation as outlined and explained in the video.

 

[HumbleHomeCook]

Awesome Shawn. I look forward to having a chance to watch it!

 

[Barmoley]

@HumbleHomeCook @Matus @M1k3 @Barmoley



Dr Larrin did a great job on this video, I've time stamped it to a very important concept in the video that is not as well understood as it should be among us knife guys.

There are two main types of martensite which are dependent on heat treatment as to which forms.

One type is more brittle and prone to creating micro cracks during its formation as outlined and explained in the video.

Funny, I was just getting to this part reading the article as I prefer that format to the videos.

 

[M1k3]

@HumbleHomeCook @Matus @M1k3 @Barmoley



Dr Larrin did a great job on this video, I've time stamped it to a very important concept in the video that is not as well understood as it should be among us knife guys.

There are two main types of martensite which are dependent on heat treatment as to which forms.

One type is more brittle and prone to creating micro cracks during its formation as outlined and explained in the video.

Is this in reference to my question about cracks caused by diamond plates and whether resin bonded or vitrified diamond stones also cause cracks?

 

[Deadboxhero]

Is this in reference to my question about cracks caused by diamond plates and whether resin bonded or vitrified diamond stones also cause cracks?

Just what I shared, nothing more.

 

[captaincaed]

I tried my hand at heat treating with a forge. I used a range of different low alloy steels and measured each for hardness and toughness to see if I could successfully pull off good properties with little or no experience. I used the information gathered in my previous article/video about the best prior microstructure for forge heat treating.

Article: How to Heat Treat Knife Steel in a Forge - Knife Steel Nerds

Video:

This is very cool, and was a great way to sit with a cup of coffee.

Since the heat treat here depends on normalizing first, how possible is this to do with a forge alone, if that's all you have access to?

Also, what behavior would you expect on carbide size based on this overall method?

Thanks for continuing to educate.

 

[Larrin]

This is very cool, and was a great way to sit with a cup of coffee.

Since the heat treat here depends on normalizing first, how possible is this to do with a forge alone, if that's all you have access to?

Also, what behavior would you expect on carbide size based on this overall method?

Thanks for continuing to educate.

My thermal cycling video/article covers doing the preliminary steps in the forge. It is not especially difficult to do. Maybe tempilstiks are a good use for that if you are concerned about getting a specific temperature. But normalizing can be done from a relatively wide range of temps.

Carbide size would be as small or smaller than when heat treating from the spheroidize annealed condition.

 

[captaincaed]

My thermal cycling video/article covers doing the preliminary steps in the forge. It is not especially difficult to do. Maybe tempilstiks are a good use for that if you are concerned about getting a specific temperature. But normalizing can be done from a relatively wide range of temps.

Carbide size would be as small or smaller than when heat treating from the spheroidize annealed condition.

Thanks as always for the Q&A round!

 

[Matus]

I need to find the time to watch this. Definitely makes me curios.

 

[HumbleHomeCook]

@Deadboxhero you're going to have to design a neck/shoulder strengthening routine for @Larrin to carry that brain around!

Also, let me just say that I loved the line, "it's harder to smoke a brisket than heat treat steel in a furnace."

Very cool stuff as always and really speaks to the variability in "uncontrolled" heat treating. A lot of work is put into a piece before this step so why not make the most of it with excellent HT, even if it means outsourcing as Larrin suggests?

I need to watch it again as I got interrupted a couple times.

 

[Deadboxhero]

@Deadboxhero you're going to have to design a neck/shoulder strengthening routine for @Larrin to carry that brain around!

Also, let me just say that I loved the line, "it's harder to smoke a brisket than heat treat steel in a furnace."

Very cool stuff as always and really speaks to the variability in "uncontrolled" heat treating. A lot of work is put into a piece before this step so why not make the most of it with excellent HT, even if it means outsourcing as Larrin suggests?

I need to watch it again as I got interrupted a couple times.

Yeah I just think it's interesting how big a role something like carbon in solution plays a huge role in these simple carbon steels.

We can have a two knives at the same HRC but one can be more chippy and less resilient.

So saying a specific HRC alone is inherently bad or brittle is not necessary accurate per say as HRC cannot distinguish the nuances in the microstructure.

Leaves a lot of questions without having the control to run hardness curves to see what specific temperatures and times are popping, and dropping.

Especially if heat treating by eyeball, using a slower than recommended oil and file testing for hardness.


There's only micro cracking during martensite formation If heat treated poorly for example. Too much carbon in solution which is very easy to do with these simple steels, They dissolve carbides incredibly easy.

 

[HumbleHomeCook]

Yeah I just think it's interesting how big a role something like carbon in solution plays a huge role in these simple carbon steels.

We can have a two knives at the same HRC but one can be more chippy and less resilient.

So saying a specific HRC alone is inherently bad or brittle is not necessary accurate per say as HRC cannot distinguish the nuances in the microstructure.

Leaves a lot of questions without having the control to run hardness curves to see what specific temperatures and times are popping, and dropping.

Especially if heat treating by eyeball, using a slower than recommended oil and file testing for hardness.


There's only micro cracking during martensite formation If heat treated poorly for example. Too much carbon in solution which is very easy to do with these simple steels, They dissolve carbides incredibly easy.

One thing I found very interesting when I slid into the kitchen knife world from the folding/sporting knife world is the way HT is viewed by the community. It's important in both and oft discussed but in a different way.

In the sporting knife world, HT is more around the HRC for a given steel. For example, M390 at 58 vs 61 or whatever. It's a much more generalized discussion.

In the kitchen knife world it is much more focused, "Smith/Maker ___________ has excellent heat treat." Or, "he really knows how to get the most out of the steel." And the very common, "buy the maker, not the steel." In the kitchen knife world the HT discussion is much more individualized.

I suspect it's a reflection of how in the sporting knife world, the HT's are generally very dialed-in, controlled, and tested so by and large the "who" of the heat treat is not seen as important. Yeah, I know there's some discussion of it, Bos and custom makers and such but it's really more about the number in relation to the steel. Whereas in the kitchen knife world, there's often so much more variability because so many of the knives are done by hand all the way through. So that expertise in finding that excellent heat treat "recipe" and the ability to consistently achieve it is very much a focus for the fans.

Just some rambling thoughts...

 

[HumbleHomeCook]

I know that was painfully obvious to most, just what I was thinking and something that really did stand out to me early on.

Coming from a metal manufacturing background with ultrastrict tolerances, it's a very different view.

 

[Deadboxhero]

I know that was painfully obvious to most, just what I was thinking and something that really did stand out to me early on.

Coming from a metal manufacturing background with ultrastrict tolerances, it's a very different view.

Nah it's an interesting observation.

 

[captaincaed]

I see a few makers trying to go beyond standard heat treats in the EDC/hunter world. Notably Shawn and Kase Knives Switzerland. I'm sure there are others, just not familiar with that world as much.

 

[Barmoley]

One thing I found very interesting when I slid into the kitchen knife world from the folding/sporting knife world is the way HT is viewed by the community. It's important in both and oft discussed but in a different way.

In the sporting knife world, HT is more around the HRC for a given steel. For example, M390 at 58 vs 61 or whatever. It's a much more generalized discussion.

In the kitchen knife world it is much more focused, "Smith/Maker ___________ has excellent heat treat." Or, "he really knows how to get the most out of the steel." And the very common, "buy the maker, not the steel." In the kitchen knife world the HT discussion is much more individualized.

I suspect it's a reflection of how in the sporting knife world, the HT's are generally very dialed-in, controlled, and tested so by and large the "who" of the heat treat is not seen as important. Yeah, I know there's some discussion of it, Bos and custom makers and such but it's really more about the number in relation to the steel. Whereas in the kitchen knife world, there's often so much more variability because so many of the knives are done by hand all the way through. So that expertise in finding that excellent heat treat "recipe" and the ability to consistently achieve it is very much a focus for the fans.

Just some rambling thoughts...

I‘ve noticed the same. It is almost like science vs art. Of course both science and art exist in both worlds, but the sporting knife world seems to be a lot more technical, higher alloyed steels, more precise heat treats, a lot more steels used in general. Most sharpen using some sort of a guided system, due to higher alloyed steels abrasives preferred are different, etc. Big part of it is just pure size of the knives and how they are used, for example grind and profile are a lot more important in a gyuto than a folder, same with balance, etc. Heat treat is also discussed differently in the kitchen knife world, good heat treat is different to different people. Some consider it good if the knife sharpens well, some if it feels good on the stones, some when the edge lasts a long time. Many will discuss performance differences among different heat treats of white 2 and then claim that there is no difference among different steels… It is very interesting to me to observe both. I find it fascinating how much mystery people attribute to the making of knives and swords even though steel and working with steel is everywhere in our world.

 

[Larrin]

I guess I've never noticed a divide between EDC/hunting knives and kitchen knives in terms of heat treatment discussion, though I am actively involved in both groups so maybe it all feels like one group to me instead and I don't always notice differences. There have always been discussions about Buck 420HC or Bob Dozier D2, etc. talking about "pushing steel to its limits" or whatever the favorite phrases are of the time. Especially in custom knives but I also see comparisons with Kershaw, Spyderco, Benchmade or other companies where people talk of chippy steel, or poor edge retention, or whatever. Though often generically in terms of getting the heat treatment "right." I would never accuse forum members of having in-depth, technical discussion of material properties and the heat treatment parameters that affect them.

In recent years there seems to have been extra focus on specific hardness though I don't really remember as much of that before. Specific individuals have tried to promote their expertise by criticizing "low" hardness knives and praising the "high" hardness knives. With kitchen knives there are a lot more inexpensive Japanese bladesmiths and this forum has had several recent threads asking about who heat treats them the best. So I would think there is a recency bias at least to some extent there when it comes to perceptions between the two communities. With custom knives there is more promotion of superior heat treatment in general so maybe the greater number of custom makers to choose from affects that.

 

[captaincaed]

I would never accuse forum members of having in-depth, technical discussion of material properties and the heat treatment parameters that affect them.

With custom knives there is more promotion of superior heat treatment in general

When you sell high-end anything, you need a good story to distinguish yourself. I imagine that at least some of the heat-treatment nuance stories are told to oneself. It's something to continue striving for when the rest of your process feels nailed down, repetitive, etc.

 

[Larrin]

When you sell high-end anything, you need a good story to distinguish yourself. I imagine that at least some of the heat-treatment nuance stories are told to oneself. It's something to continue striving for when the rest of your process feels nailed down, repetitive, etc.

I was actually referring to what community members say about custom knives rather than specifically the makers. Knifemaker advertising and what is justified and what isn’t is its own discussion. I get messages from knifemakers who are doing bad heat treatments nearly everyday so it becomes easy to think they are all doing it wrong sometimes. Getting the basics right is a big step even before talking about high level stuff for some makers. It’s hard because I don’t want to generalize but also can’t discuss specific examples because that wouldn’t be cool. So I will just say some knifemakers get it right and some don’t.

I’ve had long discussions with people like Shawn about different variables and dialing things in, those types are striving for something better. Some makers say they don’t want any details or to understand what’s going on and just want a set of instructions. And that’s fine to some extent, other then if you hand them a new steel they don’t know what to do because they don’t understand the principles. But those types don’t bother me nearly as much as the makers who are told they are doing something fundamentally incorrectly and just respond with, “My customers say it’s great.” Or “Never had a problem.” Or “I chopped through a 2x4 and it survived with no damage.” Either because they are trying to save money or save face I don’t always know but I can’t understand the attitude of not wanting to improve.

 

[stringer]

I can’t understand the attitude of not wanting to improve.

This is about the only thing I've ever chose to fire anyone for. People fire themselves for fighting or stealing or not showing up. But the "I can't, I won't, and I don't want to learn" crowd is never welcome.

 

[ian]

This is about the only thing I've ever chose to fire anyone for. People fire themselves for fighting or stealing or not showing up. But the "I can't, I won't, and I don't want to learn" crowd is never welcome.

@s.

 

[captaincaed]

I was actually referring to what community members say about custom knives rather than specifically the makers. Knifemaker advertising and what is justified and what isn’t is its own discussion. I get messages from knifemakers who are doing bad heat treatments nearly everyday so it becomes easy to think they are all doing it wrong sometimes. Getting the basics right is a big step even before talking about high level stuff for some makers. It’s hard because I don’t want to generalize but also can’t discuss specific examples because that wouldn’t be cool. So I will just say some knifemakers get it right and some don’t.

I’ve had long discussions with people like Shawn about different variables and dialing things in, those types are striving for something better. Some makers say they don’t want any details or to understand what’s going on and just want a set of instructions. And that’s fine to some extent, other then if you hand them a new steel they don’t know what to do because they don’t understand the principles. But those types don’t bother me nearly as much as the makers who are told they are doing something fundamentally incorrectly and just respond with, “My customers say it’s great.” Or “Never had a problem.” Or “I chopped through a 2x4 and it survived with no damage.” Either because they are trying to save money or save face I don’t always know but I can’t understand the attitude of not wanting to improve.

Gotcha, thank you for clarifying, sorry I misread that. I really wonder when people say "this steel is great" without any qualification...

I'm also frustrated by lack of curiosity you describe. I sometimes see this divide that was describe in Zen and Motorcycle Maintenance. For some, technology (in this case steel) is seen for what it is, on the surface. There's a visceral feeling of taming natural elements with simple tools. Then there are those who see the technology for what it means, below the surface. There are huge areas of subtlety to appreciate, but those understandings can cause the visceral feeling of enjoyment to fade. The analogy used in the book was Mark Twain's appreciation for the Mississippi River when he was young versus when he learned to pilot a river boat and learned about the sand bars, shoals, docks and currents. He lost the sense of mystery he had when young, even as he gained technical knowledge, even though the new understanding he gained was rich and nuanced. I'm glad there are people who just need to strive for mastery, and help light up little corners of the world. Keeps thing interesting. I wonder if some knifemakers are committed to the romantic, surface world of knives. It's an important way to view the world, but it certainly isn't the whole world.

In my own life, I'm now thinking about carbides: size, volume, sharpening, edge feel when cutting food. Trying to think about any useful way to think and talk about subtle differences. When I watched you and Shawn talk in a video, there was a discussion of intangible "edge feel", maybe a preference for simpler steels in the kitchen. Just cool to see the conversation moving along, and then trying to follow it myself.

 

[gregfisk]

Lack of interest or to learn is something I have never understood. I too have let people go because they didn’t want to learn or didn’t want to change what they were doing.

In my mind and being retired what else is there but to learn? I’ve grown tomatoes for at well over a decade now and they get about 10’ tall. I’m growing them in pots and in Seattle. It took many years to get the process right and for the most part I enjoyed the journey. I’ve only had a couple of people ever ask me how I get them to grow so well. Even people who grow them that tell me their having trouble.

I guess I just don’t understand people who don’t want to improve themselves.

 

[ian]

It took many years to get the process right and for the most part I enjoyed the journey. I’ve only had a couple of people ever ask me how I get them to grow so well. Even people who grow them that tell me their having trouble.

I guess I just don’t understand people who don’t want to improve themselves.

Depends what your priorities are, though. There are plenty of things I do ok that I don’t have the energy to get better at… it’s exhausting trying to be perfect at everything.

 

[Deadboxhero]

Depends what your priorities are, though. There are plenty of things I do ok that I don’t have the energy to get better at… it’s exhausting trying to be perfect at everything.

That's the wrong way to look at it, improvement doesn't mean perfection, just means improvement.

Also what does "@s" mean? Too advanced for me.

 

[inferno]

good article larrin. propane and a magnet thats all i have to play with.

 

[inferno]

Also what does "@s" mean? Too advanced for me.

**** home? chicken house?

 

[inferno]

btw i think many people have waited for an article like this. many people just starting out only have access to a forge and simple carbon steel. and this shows them that they can get acceptable results with only basic equipment.

 

[ian]

That's the wrong way to look at it, improvement doesn't mean perfection, just means improvement.

Also what does "@s" mean? Too advanced for me.

I just think it’s ok to be fine with your current approach sometimes. I’m a total obsessive myself, and have a tendency to spend hours thinking about and fine tuning all the minutia in my life. And at some point, it’s just not worth it. I mean, if your job is making and selling knives, then it’s totally worth it to perfect your HT. But I remember when I was so obsessed with whisky that I tried to match the mouthfeel of the bottled water I was using to dilute it to the particular character of the whisky, and that’s just ridiculous. Sometimes it’s better to just drink a bottle of Bulleit with some tap water and be relaxed and happy.

Heh, the symbols were a reference to a kkf member that has been frustrating people by fitting stringer’s description, but sometimes my jokes are too obscure for their own good.