"It's good steel with the right HT...."

Phixt said:
Hunter got NITRO V shipped to him in bulk for large, impact cutting tools that ended up with inclusions. 3 failed in the vise on 90 degree tortures, but 2 broke on users in the field. Replace it with a known and trusted steel like 52100, right?

Hunter orders 52100 from the same source. Only problem is, they go ahead and send him a slag batch of 52100. No good for knife making. That's like making moonshine, selling the slag batch and going, 'Oh well you're blind now, our bad'.

I believe he's now thousands in the hole as he tries to replace all the recalls with cpm 3v. Talk about frustrating.

^Where these failures line up with HT I'm unsure, but I find it compelling If the US steel source can't meet standards on their shipped goods, then where does an up and coming maker turn? Evidently, turning to names, letters and numbers designated to 'steel' can be a misleading game. Perhaps it's stories and nuances like these that lead to the repetition? I dunno. I did learn one thing the hard way over the past three years: For the user, the guy and the warranty behind the knife matter far more than the 'steel' and the HT on it. Like I said, I learned this the hard way; IMO (lol) it's more than an opinion.
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The fact that those failed due to inclusions is a sign of crappy steel, not a bad HT. HT won’t change a thing if the starting material is bad.
 
Mo2 said:
Cheap budget knives won't spend the time on a good ht due to prices being so low. That's why most of the d2 is chippy and rust prone. That's why 440c and 8cr13mov is so soft. Well... It allows it to be sharpened easier and maybe a bit more abused.

Check out Carothers for instance.. They focus on ht where they have made excellent d2 unlike the China d2 you seen. And delta 3v which is very good rust resistance and very tough.

@CultroTech knives use a really good ht too. They have shown to have far longer edge retention than any manufacturer can get using the datasheet spec ht's. N690 that's like m390. Damasteel like m390 and s110v like maxamet on roids x10. There working on an m390 ht too.

Most of the mass manufacturers use a variation of the steels heat treatment protocol provided by the steel manufacturer. You can download the PDFs provided to see. But it's when a knife maker goes out of the box and knows what they are doing to make a proper ht for knives and the properties they need for an exceptional end product.

The proof is in the pudding.

Why use a high end steel name and give it a sub par ht? Cause people just see the steel name. It's a popularity thing.
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Carothers getting better corrosion resistance out of D2 and 3V is at the expense of wear resistance. The corrosion resistance is higher because there is more Cr in the matrix and less tied up as hard chrome carbides. I am not saying that those knives have no wear resistance, but it will be lower than a knife if the same steel that has lower corrosion resistance.

D2 is going to be chippy due to the microstructure. It has large chrome carbides because it is cast as I got and rolled, not made as a powder. You can reduce the chippyness but it will still be hard the sharpen and choppy compared to CPM D2.
 
H0kieengineer said:
Carothers getting better corrosion resistance out of D2 and 3V is at the expense of wear resistance. The corrosion resistance is higher because there is more Cr in the matrix and less tied up as hard chrome carbides. I am not saying that those knives have no wear resistance, but it will be lower than a knife if the same steel that has lower corrosion resistance.

D2 is going to be chippy due to the microstructure. It has large chrome carbides because it is cast as I got and rolled, not made as a powder. You can reduce the chippyness but it will still be hard the sharpen and choppy compared to CPM D2.
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From @Nathan the Machinist
http://xf.bladeforums.com/threads/any-experience-with-nathans-d2.1470902/#post-16929136

I probably have more experience with my D2 than anybody, I have them around the shop, my own skinning knife, and my steak knife. I use it all the time, it's probably my favorite steel and it has been running circles around and handing out spankings to the stainless super steels for years.

D2 is probably my favorite steel and I do a very good job with it. My heat treat for it has developed over the years and I feel it represents the best in the industry. I've been very open with other makers about what I'm doing with it and my techniques for it are now widely adopted to the point I see new makers talking about the process and unaware where it came from.

Complex steels like D2 usually have a basic "built in" grain size that results from their alloy and its reaction to an anneal. By default D2 is usually around 12-13 intercept grain size which is relatively fine grain.

Pre-quenching in D2, M2 and other complex steels is a grain refinement step that violates the "only one austenitizing per anneal" rule for these steels meant to avoid the extreme grain growth they're prone to on a second heat which creates a large fish scale style fracture. When done improperly it can have no effect or can lead to intercept grain size as low as 1 (extremely coarse).

Prequenching, when done properly, can refine the grain upwards of 17 or more, which is a very fine grain condition. This is based on research by Teledyne VASCO.

Before going further, let me state that grain refinement to this level serves no purpose in-of-itself and very fine grain, beyond a certain point, doesn't make a better knife. This is a widely misunderstood concept among makers and knife nuts. That's not what this is about.

There are a couple steps about pre-quenching I don't recommend to other makers because they have to be adjusted for each heat batch because the variations in alloy content and material condition effect the heat treat response and can lead to problems if done improperly. This is one reason I don't use D2 much any more, because every single batch needs special attention to be fully optimized. This is particularly true going from one manufacturer to another, because D2 is like hotdogs, they can all put different ingredients into it, and a .8 vanadium will react differently than a 1.2. But, when the time and temp is dialed in it refines the grain (which is not a bad thing) and puts carbon into solution, reducing the soak time and temp for the second heat which I believe may be very significant in minimizing naturally occurring structures that play hell with edge stability such as RA that converts in temper rather than during the quench.

The end result of a fully optimized D2 is a durable knife with outstanding edge retention, good corrosion resistance, and that toothy D2 edge that just keeps cutting. While not as durable as 3V, it's more durable than most, and it just keeps cutting and cutting.

Sometimes D2 can be somewhat brittle, but our final cut testing yesterday of a knife from this batch had a thin D2 knife at 18 DPS at HRC 63 cutting some 4D nails without chipping.

We're using Crucible D2 for this batch, but not their CPM version. This was not to save cost (less than $2 difference per blade) but to avoid the small rounded carbides that fall free from the edge. It's a good process to promote toughness, but it spoils one of the best properties of D2 in a knife, so we use a conventional melt.

If you'll try it, I promise you'll like it.
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He's also posted more on d2 like the spray form version Psf27 in other threads and posts.
 
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Quick, someone call CRKT and tell them this new cool thing called "heat treat" exists. I believe they are still unaware of this newfangled possess.
 
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Basp2005 said:
Quick, someone call CRKT and tell them this new cool thing called "heat treat" exists. I believe they are still unaware of this newfangled possess.
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Until recently most if not all knife makers in China don't have high end forges that can get up to Temps hot enough for the higher end steels. They really only had access to the cr steels d2 variations etc. Plus the price point for knives out of China has generally been affordable. Crkt and Kershaw buy knives in quantity for super cheap and mark them up (obviously for warranty and profits,paying makers etc). So a $8 knife goes for 30-40$ or whatever.

Ffw to 2018 and we have new companies budgeting for higher end ht ovens or out sourcing the steel to ht facilities that are capable of a in the box ht for there mass production knives using m390, s35vn etc.

That's why they now have s35vn, m390 etc.

Crkt doesn't make high end knives because it never pays off for them. They just don't have the luck. So they stick to what they do good.

Spyderco have a factory in China who is all about the higher end steels. Iirc I think it's called "maple" don't quote me on that but the guy likes to work with spyderco primarily and has some decent ht equipment. They make the bdz1 knives for spyderco because they have the capability to run the steel at the higher Temps required to ht them according to MFG specs.

Ive learned alot of this through interviews from Kershaw, Spyderco and crkt.
 
WillB said:
Maybe I'm not seeing it fully, but one part of my Q didn't get covered. Do some knife steels benefit more from a good HT than others, or does it simply go without saying that all knife steels benefit from HT? It seems clear that steel such as D2, 440HC and such with a good HT can be quality knife steels, but for others, simply following the manufacturers recs is GTG? Some manufactures will claim proprietary HT treatments also which I tend to take as marketing hoopla, unless someone confirms it third party.
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A better way of describing it than "some steels benefit more from good HT" would be "some steels are more difficult to HT properly". A lot of high-alloy steels require pre-heating at one temperature, raising it to a certain temperature for a certain time and holding it there for a specific length of time, then lowering the temperature again and holding it for another specific amount of time...and so on and so forth. Computer-controlled heat treatment ovens that have been analyzed and tweaked to eliminate hot or cold spots make a huge difference with those steels, because anything less means your variables are off and so your outcomes are inconsistent. This is part of the reason why there are heat treatment specialists out there who do nothing but heat treatment work on contract. If it was easy, folks would do it themselves. Meanwhile, stuff like O1 is generally considered to be very forgiving for backyard tinkerers to mess around with with a propane torch, some old veggie oil, and a home oven. It's not that some benefit more from being heat treated well, it's that some are more finicky than others, so it's easier to mess them up. :p
 
I would suggest that every steel does benefit from proper heat treat. Also, you can have heat treats that hit your desired hardness parameters, but miss out on the potential of the steel.

440C is a fine steel.


I have and use what would be considered low end steel with great enjoyment. I use Buck's 420HC, which they do a good job with. It is a fine balance between edge retention (lower than many), stainlessness, toughness and the great ease of sharpening. They use that steel because it is a balance of cheap, easy to blank and machine, and it is also user friendly. If you compare sharpening it to other higher carbide, higher alloy stainless like even 440C, it is much easier to maintain and to get sharp. Orders of magnitude easier, but it won't hold an edge as long.

I have met, and discussed with more than my share of old timers who were not fans of Buck's 440c steel because it was harder to sharpen for them.

I have sharpened 440c, CPM 154, 1095, 1080, 5160, ATS34, D2, CPM3V, A2, INFI (new and old, and at both their standard hardnesses 58-60, and 60-62), 52100, L6, Aus8a, VG10, VG1, S35VN, 8Cr13Mov, and a triple hand full of other steels (like whatever Victorniox, Opine, Kershaw, CRKTl and many others use).


I'm leaving out a lot.

Every maker likely has a proprietary heat treat. Some very complex, and involving steps like cryo treatment, that many other budget knives will ignore, even when using a better steel.

I've had the same steel from different manufacturers be just dandy from one, and garbage from another.
 
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