Higher hardness 1095

[me2]

There are a few of us left here that were doing quite unusual things back in the late 2000s and early 2010s. High hardness 1095 was one of those things.

There is a perception that knives should be 58 HRc by the general public. More than that and they’re “hard to sharpen”. Now, to us knife nuts, those are both untrue. However, to the rest of the world, it makes sense. There are way more people who believe that than don’t, so what does one do if they want to sell a lot of knives? First, you make those knives. Then you find people like Larrin to educate your customer base.

Also be aware there is a difference between easy to grind and easy to sharpen. Try sharpening a knife made from annealed 1095 and you’ll know the difference well.

S sodak unfortunately that was a Chicago Cutlery kitchen knife that cut all that cardboard. My M2 knife did too, but it was the Chicago Cutlery blade that convinced me to stop chasing steels and start chasing sharpening and geometry.

 

[me2]

I like the idea of a simple, high hardness slicer. Minor point: you'd probably rather have 1084 or 80CrV2, as it's my understanding that they'll be simpler to heat treat and outperform 1095 on toughness by a wide margin while offering no tangible downsides.

A question I would ask, though, is if I were to ask a bladesmith who's capable of making custom heat treated, high performance knives to make me something in 1084, why wouldn't I just ask them to use AEB-L or 14C28N? The steel cost difference is minimal and their work and expertise is going to be expensive either way, so I'd think you'd get more for your money by selecting a simple steel that has a better overall balance of properties. I don't mean any offense by that question; I would love to understand what about 1084/1095 makes folks happier than using the high edge stability stainless options.

While it’s not a lot, 1095 has some carbide volume and increased wear resistance over 1084. I don’t want to speculate on 80CRV2, but 1095 might have more wear resistance than that too, though the alloying will make a big difference. If one has the control to wring HRc 66 performance from 1095, then 1084 and 80CRV2 won’t much matter in terms of ease of heat treating.

One reason regarding AEB-L relative to other steels is it wasn’t as common or popular back when this type of thing was being discussed. The other is it’s difficult to get hardness that high in stainless steels after tempering.

One other point regarding these high harness simple alloys. Alvin did a LOT of research before making his knives. However he was using older sources that aren’t typically available today. His heat treatments were based on standard industrial treatments from the 50s and 60s and maybe 70s. The chosen hardnesses were a byproduct of the tempering temperatures he used. Those temperatures were chosen to reach a toughness peak in the respective steels that was shown using a torsional toughness test. This is an old test and isn’t really used anymore. It was devised to test toughness of high hardness/low ductility materials and reduce the data scatter such materials tend to have. I wish I had known about it when I was doing toughness testing of ductile cast iron.

Charpy testing in most cases is done with a notch in the sample, typically a V shape. However more brittle material uses a C shape or no notch at all. Torsional testing was a step beyond un-notched Charpy testing. However, it is more expensive and much harder to find someone to do it. I’ve tried. The older versions of the Metals Handbook discuss the wide scatter sometimes found in Charpy testing. Larrin can speak on that, having done more of it than I have on more knife related materials. I used to test bridge plates and welded samples and they would max out a 300 ft-lb machine with a V notched specimen. Nothing like we discuss here.

 

[DeadboxHero]

While it’s not a lot, 1095 has some carbide volume and increased wear resistance over 1084.

The difference is marginal, 1084 still has plenty of undissolved Fe3C unless over-austenitized.

 

[marrenmiller]

Simple answer, because I want it.

Long answer, I have a Delica and Stretch in K390 or CruCarta PM2 and I doubt I could get much better without paying a whole lot more. This is just a novelty desire item, nothing more. I'm certainly not out to convert anyone. It's almost like trying to chase down a ghost to prove a point if to no one else but myself.

I see, thanks for explaining.

If you haven't already, I recommend you pay a knifemaker to regrind one of your tool steel Spydercos. I have a bunch that are crazy thin and they're the most incredible user knives I've owned. I won't name names but regrind services are really inexpensive.

 

[me2]

The difference is marginal, 1084 still has plenty of undissolved Fe3C unless over-austenitized.

Is that your 1084 or from a reference photo of someone using a heat treatment specifically intended to leave undissolved carbide? In any case, yes the difference is not great.

 

[DeadboxHero]

Is that your 1084 or from a reference photo of someone using a heat treatment specifically intended to leave undissolved carbide? In any case, yes the difference is not great.

That is my micrograph from my 1084.

Yeah, it's interesting because 1084 is known for being easy to heat treat because the as quenched hardness can stay relatively the same over a large range of austenitizing temperatures but the microstructure will be very different and so will the edge performance even at the same HRC.

Perhaps 1084 is not as easy to HT as it's given credit for especially with the extremely low hardenability.

 

[marrenmiller]

One reason regarding AEB-L relative to other steels is it wasn’t as common or popular back when this type of thing was being discussed. The other is it’s difficult to get hardness that high in stainless steels after tempering.

That's fair. I am really only speaking in a modern context.

AEB-L may not get quite as hard as 1095, but it supposedly hits 65 HRC with a reasonable HT protocol and I'm sure dedicated makers like Triple B may be able to push the envelope even further. Maybe you won't get an optimum microstructure from doing so, but for that I'd defer to more educated individuals.

 

[me2]

It's not really a concern in the production setting. When the steel is bought and received it is in the annealed condition from the mill. Manufacturers often have there blades cut out from the sheet with laser or water jet including the holes for the handles. All of that is done before sending out for heat treatment.

There can be some important details missing in the HT causing problems even at the same HRC

For a custom knife, you also drill the holes in the tang before hardening not after so it's not a factor.

As far as chipping during finishing, that is a big sign that the heat treatment is straight junk or very poor practices are being used which either can be ruled out.


Here is an example, I made and heat treated a knife in 1084 which is 64.0rc after tempering.

After finish grinding in prep for hand sanding, no chipping, again handle holes drilled before HT.

After hand sanding and tapering tang nice and thin again, no chipping.
[Video]

https://imgur.com/xNFYdnM

After finishing and sharpening the knife, no difficulty in sharpening and no chipping.

Microstructure, Microstructure, Microstructure.

Dr. Benson, is that you?

 

[sodak]

[...]

S sodak unfortunately that was a Chicago Cutlery kitchen knife that cut all that cardboard. My M2 knife did too, but it was the Chicago Cutlery blade that convinced me to stop chasing steels and start chasing sharpening and geometry.

Thanks for the correction, it's been a few years....

 

[LostCause]

I have S390 at 66/67 HRC. I love that thing.

 

[me2]

Those two knives are probably more responsible for me spending less time here than any others. If a $10 kitchen knife can cut that much, and I can sharpen it that fast, then these harder steels aren’t really going to help me if they’re 10-20x the price.