What carbon steel has equal or better edge retention than zdp?

I was talking about 7 deg per side. I agree that 7 deg included is probably pushing the all theoretical limits. My straight razor has a larger included angle than that and its edge is failing, cutting thread.

Well, I am not saying that the Landes model *fails* at larger geometries, but that it becomes *irrelevant* at larger geometries for practical applications. For the USER it matters little, what the failure mode of an edge is, but it matters a lot, WHEN it fails. Nozh's tests for example have shown that at 12-15 deg per side, the carbide richer steels easily outperform those that Landes is advocating. Phil Wilson has noted that for his geometries and applications, the high carbide volume steels have outperformed others with smaller carbide fraction and they are not the only ones to have experienced this.

So really the remaining question is: what is a sensible geometry for a given task and will the Landes model help me pick the best steel given that geometry? Is the geometry, I want, so small, that i have to be mindful of edge stability? It seems to me that quite a few people have come to the wrong conclusion. As I have pointed out in my first post, this is not necessarily fault of the model, but with how it is promoted. The way I see the Landes model being promoted is that lower (angle) is better and therefore finer grained steels with smaller carbide fraction are better than coarser grained steels with higher carbide fraction, without stating under which conditions lower is better and how low is too low.

As to the model itself: I think it is a useful tool but I think it also important to keep in mind its limitations. It is a purely geometrical argument not considering any chemical interactions. It does not distinguish between different types of carbides (beyond their geometrical shape). It can not explain, why there have been such varying experiences with S30V or why ZDP-189 feels so much different than S30V or ATS-34 for that matter.

As to the cutting technique: It seems to me backwards to adjust the technique (as long as it is not fundamentally wrong) rather than the tool. I would say that the tool is there to do my bidding not the other way round. As I have tried to say before: it is not that the typical rocking motion of the "french technique" can be considered as irresponsible abuse.
 
Please correct me if I'm wrong- If I understand the Landes model, shouldn't it allow (or dictate) a chart that would indicate "steel x at hardness y should be sharpened at angle z for optimal performance" ? z would be the lowest edge angle that steel at that hardness could maintain, and obviously, you could work up from there for more durability.

Does this chart exist, or is this all still theory? Or am I completely missing the point of all this?
 
HoB said:
I was talking about 7 deg per side. I agree that 7 deg included is probably pushing the all theoretical limits. My straight razor has a larger included angle than that and its edge is failing, cutting thread.
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Yipes! At 4.5-5 per side, my chef knife cuts pineapples and watermelon with no damage (I damaged it later :o ). Maybe the spread-out surface helps a lot?

HoB said:
Well, I am not saying that the Landes model *fails* at larger geometries, but that it becomes *irrelevant* at larger geometries for practical applications. For the USER it matters little, what the failure mode of an edge is, but it matters a lot, WHEN it fails.
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I suppose "grind it as thin as you can and if it don't hold up, thicken it a little until it does" would work just as well, but I like more detailed information when it's available.

HoB said:
Nozh's tests for example have shown that at 12-15 deg per side, the carbide richer steels easily outperform those that Landes is advocating.
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His tests have also shown a 420HC Buck Nighthawk had better edge-retention than an INFI blade, so carbide-poorer steels seem to do well, as well (just not as good as S90V, CPM-10V, and the like).

HoB said:
Phil Wilson has noted that for his geometries and applications, the high carbide volume steels have outperformed others with smaller carbide fraction and they are not the only ones to have experienced this.
Click to expand...

Among the kitchen cutlery enthusiasts with whom I talk, the observation has been that the fine-grained steels keep their 'scary sharp' edge longer than the coarse-grained steels (the powder super alloy stuff), but the coarse-grained steels hold an "80% sharp" edge much much longer. The chefs who are giving me correspondence help with Japanese-style knife cuts both prefer powdered tool steel blades for their main chef knife, so all of those observations fit in with what you and Wilson have observed, but the info is used differently (sharpness trumps edge-retention for certain cuts and edge-retention trumps sharpness for general work). In my non-cooking knife work, my 13C26 pocketknives hold the edge I want better than S30V pocketknives and worse than M2 pocketknives, so make of that what you will.

HoB said:
So really the remaining question is: what is a sensible geometry for a given task and will the Landes model help me pick the best steel given that geometry?
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I must plead ignorance on that one. I've seen Landes' .pdf file on the subject and his writings on a few English language fora and a pleasing array of micrographs from all sorts of people since then (most coming from Larrin), but since there are so many steels and so many ways to heat-treat each steel, I think it'd only allow for choosing general classes. Also, I haven't bought and read Messerklingen und Stahl just yet.

HoB said:
Is the geometry, I want, so small, that i have to be mindful of edge stability? It seems to me that quite a few people have come to the wrong conclusion. As I have pointed out in my first post, this is not necessarily fault of the model, but with how it is promoted. The way I see the Landes model being promoted is that lower (angle) is better and therefore finer grained steels with smaller carbide fraction are better than coarser grained steels with higher carbide fraction, without stating under which conditions lower is better and how low is too low.
Click to expand...

Fine-grained steels not only take smaller edges with greater ease (thanks to diamonds and SiC, any steel can take any edge), but they're also tougher, so a preference for them need not be dependant solely on wanting to sharpen edges at 10-12 degrees per side.

HoB said:
As to the model itself: I think it is a useful tool but I think it also important to keep in mind its limitations. It is a purely geometrical argument not considering any chemical interactions. It does not distinguish between different types of carbides (beyond their geometrical shape). It can not explain, why there have been such varying experiences with S30V or why ZDP-189 feels so much different than S30V or ATS-34 for that matter.
Click to expand...

Good points. Though, on S30V, it can explain why people who keep the factory or maker-chosen angle like that stuff more than I do. :)

HoB said:
As to the cutting technique: It seems to me backwards to adjust the technique (as long as it is not fundamentally wrong) rather than the tool. I would say that the tool is there to do my bidding not the other way round. As I have tried to say before: it is not that the typical rocking motion of the "french technique" can be considered as irresponsible abuse.
Click to expand...

Actually, it was a serendipitous discovery. I had been using the French techniques for a few months with various chef knives and was enjoying having any skillset over none. I was interested in learning the Japanese way of using a chef knife since most of mine are Japanese-style French-style chef knives (wa-gyuto and yo-gyuto bring me many smiles) and noticed the lack of damage to my thinnest knife's edge even though I was still making the same beginner mistakes made with French-style cutting.
 
thombrogan said:
His tests have also shown a 420HC Buck Nighthawk had better edge-retention than an INFI blade, so carbide-poorer steels seem to do well, as well (just not as good as S90V, CPM-10V, and the like).
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It is more complicated - for 800 cuts 420HC (on CS ODA from Taiwan) degradate to extent it can not cut anything, while INFI continue to keep some edge. But INFI lose high sharpness very fast.

I can not say that 420HC do well as well as CPM S30V.

420HC stay well at first while INFI stay well at last, but CPM S60V outcut both.

So 420HC I tested seems to be good for someone who need high shrpness and may sharpen it frequently and INFI is good for someone who can not resharpen it time to time, but do not really need high sharpness.

Thanks, Vassili.
 
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