Random Thought Thread

Either I’ve been spoiled by custom heat-treated steels, or the factory heat treatment of mass-market blades is just plain awful?

Lately I’ve sharpened more than a dozen folding and fixed knives with various steels — sometimes even supposedly “pure cutting steels” like ZDP-189, Cowry-Y, M398, Cromax, S125V, M390, RWL-34.

And none of the above hold an edge — not even close — compared to any literally standard steel that’s been heat-treated more or less competently, not even excellently or perfectly…
 
Moorik said:
Either I’ve been spoiled by custom heat-treated steels, or the factory heat treatment of mass-market blades is just plain awful?

Lately I’ve sharpened more than a dozen folding and fixed knives with various steels — sometimes even supposedly “pure cutting steels” like ZDP-189, Cowry-Y, M398, Cromax, S125V, M390, RWL-34.

And none of the above hold an edge — not even close — compared to any literally standard steel that’s been heat-treated more or less competently, not even excellently or perfectly…
Click to expand...
A lot will get burnt edges also , and it can take time to sharpen that out
 
yoko said:
A lot will get burnt edges also , and it can take time to sharpen that out
Click to expand...
It doesn’t help at all. I tried everything, even removing the excess steel along the edges.
I’m not even talking about the fact that very often, judging by the feel, the hardness is clearly lower than what is claimed.
I can’t check it on a hardness tester.
However, during sharpening I can often tell—both under a microscope and by the tactile feedback—when there is an obvious lack of hardness or something else is off.
On top of that, most of these steels don’t really take fine abrasives at all.
Something like 40/28 (300–500 grit) already seems to be too fine for them, as if it’s excessive.
 
Moorik said:
Either I’ve been spoiled by custom heat-treated steels, or the factory heat treatment of mass-market blades is just plain awful?

Lately I’ve sharpened more than a dozen folding and fixed knives with various steels — sometimes even supposedly “pure cutting steels” like ZDP-189, Cowry-Y, M398, Cromax, S125V, M390, RWL-34.

And none of the above hold an edge — not even close — compared to any literally standard steel that’s been heat-treated more or less competently, not even excellently or perfectly…
Click to expand...
Depends on the maker. The good guys are still good. I.E. Spyderco, Buck, BM.... you know who they are.
 
Moorik said:
It doesn’t help at all. I tried everything, even removing the excess steel along the edges.
I’m not even talking about the fact that very often, judging by the feel, the hardness is clearly lower than what is claimed.
I can’t check it on a hardness tester.
However, during sharpening I can often tell—both under a microscope and by the tactile feedback—when there is an obvious lack of hardness or something else is off.
On top of that, most of these steels don’t really take fine abrasives at all.
Something like 40/28 (300–500 grit) already seems to be too fine for them, as if it’s excessive.
Click to expand...

Maybe ask the manufacturer?

I currently only have 1 of the steels you mentioned (m390) and don't have issues with edge holding
 
yoko said:
Maybe ask the manufacturer?

I currently only have 1 of the steels you mentioned (m390) and don't have issues with edge holding
Click to expand...
From my experience, M390 is exactly the steel that most often has problems with edge retention—roughly with about 90% of manufacturers.
It’s rare to come across truly good heat treatment on M390.
By the way, I’d put factory Magnacut in the same category.
And again, is the edge retention really that good?
Like, after cutting 40–50 pounds of meat, does it still cut paper?
Edit:
I’m not blaming the steel itself, I’m blaming the heat treatment.
I tested a custom Magnacut on rope, and it cut just as much as a good S90V.
 
Moorik said:
It doesn’t help at all. I tried everything, even removing the excess steel along the edges.
I’m not even talking about the fact that very often, judging by the feel, the hardness is clearly lower than what is claimed.
I can’t check it on a hardness tester.
However, during sharpening I can often tell—both under a microscope and by the tactile feedback—when there is an obvious lack of hardness or something else is off.
On top of that, most of these steels don’t really take fine abrasives at all.
Something like 40/28 (300–500 grit) already seems to be too fine for them, as if it’s excessive.
Click to expand...
Many manufacturers will run their steels lower than optimal to prevent complaints about broken blades and chipping. To be honest, the average users (not aficionados) will never notice the hardness, but will notice a broken blade.
 
Moorik said:
It doesn’t help at all. I tried everything, even removing the excess steel along the edges.
I’m not even talking about the fact that very often, judging by the feel, the hardness is clearly lower than what is claimed.
I can’t check it on a hardness tester.
However, during sharpening I can often tell—both under a microscope and by the tactile feedback—when there is an obvious lack of hardness or something else is off.
On top of that, most of these steels don’t really take fine abrasives at all.
Something like 40/28 (300–500 grit) already seems to be too fine for them, as if it’s excessive.
Click to expand...

Production companies often heat treat too soft. They also frequently do this thing called lying. It's quite unfortunate.
 
ferider said:
Not so good, the S90V then (or different geometry?) - try Spyderco S90V.

View attachment 3067968

Heat treat is one thing. The other thing I (now) watch out for is that a maker grinds wet.
Click to expand...
To be honest, the edge retention values in tests like CATRA may not always reflect real-world edge holding in everyday tasks.

What do we actually cut in daily life?
Cardboard, meat, vegetables, wood, fruits, occasionally fabric, plastic film, or some kind of plastic.

In addition, heat treatment, in my opinion, plays an absolutely crucial role.
When comparing one steel to another, what matters is the quality and the focus of the heat treatment for those specific steels.
If one steel is heat-treated purely for maximum edge retention, while another is optimized for a versatile EDC context, the results will differ significantly.

In some situations, edge retention and the ability to sharpen/polish the cutting edge to a very fine grit are important.
The question isn’t just about hardness, because if the steel is too hard, the edge can chip or crumble.
Interestingly, as far as I understand, in CATRA tests a steel can still show higher scores even if it’s frankly too brittle/hard.

I’ve noticed that steels which hold an edge well while also being tough are often not extremely hard.
I personally have a record-holding knife in CPM 15V that outcuts even the best Rex 121 blades, and its hardness is 65 HRC.
At the same time, as far as I know, Spyderco’s 15V can reach 66–67 HRC.
 
What I mean is that on charts showing steel toughness versus edge retention, in the context of edge retention specifically, many steels can effectively be shifted to the right—towards better edge retention.

That's why I try not to rely too heavily on those charts.

Because the steel itself doesn't deliver an absolutely fixed result as indicated in the test.

The same heat treatment can produce different characteristics depending on various variables.
 
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