The Effect Of “Edge Aggression” Between Steels

Find deals on amazon
Shop Knives and stones on ebay
Advertise with us
Kitchen Knife Forums

Help Support Kitchen Knife Forums:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Barmoley

Barmoley

Rant specialist extraordinaire
KKF Supporting Member
Joined
Aug 12, 2016
Messages
4,331
Reaction score
8,370
Location
USA
We've discussed many times that it seems that some steels have bittier, grabbier edges than others. Even though I've experienced this myself, I tended to attribute this to my imagination or possibly the effect of the grit that I finished the edge on. It never fully made sense to me since I've experienced this even when finishing different steels on the same grid, but I still didn't fully believe that the effect is real even though there is much anecdotal evidence of there being something there. Fortunately, Shawn Houston @Deadboxhero of the triplebhandmade fame did a very cool study on the subject and the results are very interesting.
 

Attachments

  • The Effect Of “Edge Aggression” Between Steels.pdf
    9.1 MB · Views: 0
Interesting, definitely love to see more testing. I’ve also seen argument that Martensite structural difference between carbon steel and alloyed steel is also causing the bityness. (Lath martensite vs plate martensite)
 
eddworks said:
But, but... I like 52100 a lot.
Click to expand...
So do I, nothing wrong with liking 52100, but if you were making a dedicated tomato knife it might not be the best choice 🤷‍♂️

It is so great to see these studies done by the juggernauts of our community. The more we know and the better we understand what is actually going on in all things knife the less mystique and misinformation there will be. At least I hope so.
 
blokey said:
Lath for carbon and plate for alloyed, the original article I read was in Chinese so there might be bit translation error
Click to expand...
Interesting. I found it was the opposite. The simple carbon steels are more prone to developing plate martensite since the cementite dissolves rapidly past Ac1 easily putting too much carbon solution if a proper time and temperature isn't selected.

Meanwhile, in tool steels, the other metallic elements in alloy carbides found in tool steels don't have as much atomic mobility in the steel matrix and the atomic bonds between the carbon and metallic elements very stable at high temperatures even with long soak times approaching equilibrium.

Most of the large amounts of carbon you see in the chemistry of tool steels remains locked up in undissolved carbides which is what contributes to the wear resistance despite having a lower carbon martensite.
 
Deadboxhero said:
Interesting. I found it was the opposite. The simple carbon steels are more prone to developing plate martensite since the cementite dissolves rapidly past Ac1 easily putting too much carbon solution if a proper time and temperature isn't selected.

Meanwhile, in tool steels, the other metallic elements in alloy carbides found in tool steels don't have as much atomic mobility in the steel matrix and the atomic bonds between the carbon and metallic elements very stable at high temperatures even with long soak times approaching equilibrium.

Most of the large amounts of carbon you see in the chemistry of tool steels remains locked up in undissolved carbides which is what contributes to the wear resistance despite having a lower carbon martensite.
Click to expand...
Yeah I probably messed up these 2, the Chinese translation is totally different for these 2
 
This study appears to align with my real-world experience.

I'm a fan of low grit sharpening for seemingly longer edge retention, plus a raggedy carbide structure tends to add to the effect. Downside would be a decrease in edge toughness/stability, which makes it kinda scary to put a nail-flexing edge on it.

It wouldn't surprise me if carbides are cracking and/or falling out of the edge of the 440c - temporarily "refreshing" it.

52100 is so silky smooth in comparison, and stuff like the White steels go even further in that direction...
 
Last edited:
As always, it's great seeing this work and also as always, of course @Deadboxhero is out in front of it! Good stuff Shawn.

I spend so much time in the sub-micron world that when I see those 10+um blobs on the micrograph they look ginormous! 😁

When the Cutlery Hall of Fame is christened, you and @Larrin should be in an early class for your gold jackets.
 
HumbleHomeCook said:
As always, it's great seeing this work and also as always, of course @Deadboxhero is out in front of it! Good stuff Shawn.

I spend so much time in the sub-micron world that when I see those 10+um blobs on the micrograph they look ginormous! 😁

When the Cutlery Hall of Fame is christened, you and @Larrin should be in an early class for your gold jackets.
Click to expand...
Too fancy for me.

Thanks man.
 
Kippington said:
This study appears to align with my real-world experience.

I'm a fan of low grit sharpening for seemingly longer edge retention, plus a raggedy carbide structure tends to add to the effect. Downside would be a decrease in edge toughness/stability, which makes it kinda scary to put a nail-flexing edge on it.

It wouldn't surprise me if carbides are cracking and/or falling out of the edge of the 440c - temporarily "refreshing" it.

52100 is so silky smooth in comparison, and stuff like the White steels go even further in that direction...
Click to expand...
Apexultra workpony soon?
 
Forgive me if I'm getting confused by the Imperial system, but in this table I guess the inches are in fact centimetres.
Screenshot_20231121_062102_Adobe Acrobat.jpg
 
Does measuring the thickness at .5" behind the edge would make much sense? 5mm were more relevant. Finding a .4mm thickness right behind the edge — worse than most Wüsthof?
 
Last edited:
eddworks said:
But, but... I like 52100 a lot.
Click to expand...
I enjoyed "your 52100" quite a lot!
It had an aggressive bite to it I only know from Aogami Super. The explanation probably simply lies in how you sharpen it, I guess?

52100 has quite high values of toughness and edge retention according to (was it Larrin?) so it is surprising you don´t see it used more often for kitchen knives. I like it very much!
 
I suspect on an atomic level a Carbon steel like Shirogami #1 with it's low alloying components would
have a cleaner edge than a very alloyed steel like a Stainless due to its various cabides which would
have different sizes.

The person sharpening the blade and methods used to also factor in the end result.
 
jaydee said:
I enjoyed "your 52100" quite a lot!
It had an aggressive bite to it I only know from Aogami Super. The explanation probably simply lies in how you sharpen it, I guess?

52100 has quite high values of toughness and edge retention according to (was it Larrin?) so it is surprising you don´t see it used more often for kitchen knives. I like it very much!
Click to expand...
52100 has very good toughness but isn't all that great for edge retention, although I do wonder how well the abrasive tests commonly used correlate to "respectful" kitchen use.
 
52100 can vary quite a bit depending on the heat treat approach - would be interesting to know how the sample was HTd
 
Benuser said:
Does measuring the thickness at .5" behind the edge would make much sense? 5mm were more relevant. Finding a .4mm thickness right behind the edge — worse than most Wüsthof?
Click to expand...
As long as geometry is consistent between the samples does it even matter?

The Forest Ninja said:
I suspect on an atomic level a Carbon steel like Shirogami #1 with it's low alloying components would
have a cleaner edge than a very alloyed steel like a Stainless due to its various cabides which would
have different sizes.

The person sharpening the blade and methods used to also factor in the end result.
Click to expand...
AEB-L is very alloyed compared to shirogami #1 and it has very small uniformed carbides and I don't think anyone would complain that it doesn't have a clean edge or doesn't get sharp. Who does the sharpening and how obviously matters and this is why it is important that these were sharpened as close to each other as possible. I don't think anyone would argue that sharpening with different grits would have this effect, but it is curious to see if the steel micro structure itself creates a similar effect.

Also, no one is saying 52100 is a bad steel or bad for kitchen knives or worse than 440C for kitchen knives. A low and a high alloy steels had to be picked and these are good candidates.
 
jaydee said:
I enjoyed "your 52100" quite a lot!
It had an aggressive bite to it I only know from Aogami Super. The explanation probably simply lies in how you sharpen it, I guess?

52100 has quite high values of toughness and edge retention according to (was it Larrin?) so it is surprising you don´t see it used more often for kitchen knives. I like it very much!
Click to expand...
I had the same experience with my Eddworks gyuto, so much so that I reached out to him to see how he sharpened. It was so toothy out of the box I though it was done on a belt grinder. He uses DMT stones (this could have changed) and I have started to since as well. The DMT extra fine followed by a strop makes a killer edge for tomato/peppers etc. That being said if I go to a higher grit stone I understand this better. Some steels feel "sticky" on my fingers while others dont. It means nothing to me as far as retention but its what I call "scary" sharp vs just toothy.
 
You must log in or register to reply here.

Latest posts

Back
Top