Why is Sharpening a crappy knife steel so much easier than sharpening a good steel?

D

dzlvs8

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Why is it so much easier to sharpen most knives with crappier steels than it is to sharpen knives with 154cm, S30V, etc.? I would think that harder steels would develop a burr less quickly, thus requiring less time perfectly removing the burr. However, it seems to be the opposite. I can sharpen cheap knives with my eyes closed. It’s almost harder to mess it up than do it right.

(The sharpening method I am referring to is sharpening on Arkansas and synthetic stones….(a Smiths tri-stone).
 
Because in most cases the "crappy steel" has a better heat treatment. It's not as easy to heat treat steels like S30V so corners get cut and while still better in performance they still lack on the HT which shows in sharpening.
 
I would say they're probably softer in most cases which will allow them to be sharpened easier but will also allow them to dull quicker.
 
My first guess would that the amount of carbides makes sharpening hihger class steel mor difficult. Cheap steels do only have enough carbon to be somewhat hardened, leaving almost no carbon for the creation of carbides. In those steels that you mentioned edge retention is mainly based on carbides that give the steel its cutting teeth. The hardness also comes into play, as soft steels quickly lose any carbides they might have, where harder steels offer a stronger base for the carbides.
 
Hmmm. I was expecting an easy defi it I've answer. The third explanation sounds pretty scientific but still sounds a little like speculation. Basically, my only thought was, less strokes to sharpen a crappy soft steel = less bad strokes that screw up an edge. Thus, if I switched to diamond I stead of Arkansas stones I would get noticeably better sharpening results.
 
Some really 'crappy' steels are a PITA to sharpen, simply because the grain size or structure, or hardness (too soft or too brittle), won't allow them to take and/or hold a fine edge. More often than not, that all comes down to heat treat issues, and not necessarily the type of steel itself.

I'd say a 'crappy' steel (as perceived by type only) that sharpens up easily, and hopefully holds a fine edge reasonably well, really isn't so 'crappy' after all. That's what knife steel is supposed to be. A knife steel which sharpens easily, but isn't wear-resistant like many modern 'super steels' (the alleged 'good' steels), isn't actually bad, it's just living up to it's design specs. ;)

Ease of sharpening is mostly about knowing what abrasives work well for a given steel. Higher wear-resistance due to vanadium carbides, such as in S30V for example, can be made 'easier to sharpen' by using abrasives that'll handle the carbides well (diamond, CBN). Middle-of-the-road steels with moderate wear-resistance, like 154CM, 440C, D2, etc. respond 'easily' to aluminum oxide and silicon carbide (and diamond/CBN, but they're not necessary). Simple low-wear steels like 420HC (wrongly perceived as inferior, much of the time) or 1095, are usually easier to finesse with gentler abrasives like natural (Arkansas), aluminum oxide or even silicon carbide. If using harder abrasives like diamond on these, it's easier to control the process using finer grits, as the coarser-grit super-abrasives will be overkill, most of the time. That 'overkill' means it's very difficult to refine edges, which in turn makes sharpening these 'simpler' steels 'not so easy' anymore.


David
 
Last edited:
Obsessed with Edges said:
Some really 'crappy' steels are a PITA to sharpen, simply because the grain size or structure, or hardness (too soft or too brittle), won't allow them to take and/or hold a fine edge. More often than not, that all comes down to heat treat issues, and not necessarily the type of steel itself.

I'd say a 'crappy' steel (as perceived by type only) that sharpens up easily, and hopefully holds a fine edge reasonably well, really isn't so 'crappy' after all. That's what knife steel is supposed to be. A knife steel which sharpens easily, but isn't wear-resistant like many modern 'super steels' (the alleged 'good' steels), isn't actually bad, it's just living up to it's design specs. ;)

Ease of sharpening is mostly about knowing what abrasives work well for a given steel. Higher wear-resistance due to vanadium carbides, such as in S30V for example, can be made 'easier to sharpen' by using abrasives that'll handle the carbides well (diamond, CBN). Middle-of-the-road steels with moderate wear-resistance, like 154CM, 440C, D2, etc. respond 'easily' to aluminum oxide and silicon carbide (and diamond/CBN, but they're not necessary). Simple low-wear steels like 420HC (wrongly perceived as inferior, much of the time) or 1095, are usually easier to finesse with gentler abrasives like natural (Arkansas), aluminum oxide or even silicon carbide. If using harder abrasives like diamond on these, it's easier to control the process using finer grits, as the coarser-grit super-abrasives will be overkill, most of the time. That 'overkill' means it's very difficult to refine edges, which in turn makes sharpening these 'simpler' steels 'not so easy' anymore.


David
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Thank you David, that explantion was very helpful for this newbie. Well stated. Good job.
 
When you say crappy knife and good knife. How are you defining those terms? Just the steel used? The way they are manufactured? hand made or production? There are a lot of factors that go into quality with any product. Lower end (of expense) knives can be softer which makes them quicker to grind. Not really easier though. Newer high carbide steels can take longer to grind cause of the amount of super hard carbides in it. These steels can also be chippy if using a lot of force to grind or using a higher grit abrasive that isn't hard enough or isn't designed to cut the carbides themselves. Purer steels don't usually see these issues. Burr formation and ease of removal can be affected by the natural ductility of the steel used. Also by the heat treat selected or by how well implemented the heat treat was and by post heat treat care. Heat treat also effects the grain structure of the steel which will have an effect on how fine of an edge you can obtain. Hand made knives or high quantity/low quality knives can have very uneven grind line which can cause a lot of confusion when grinding at a consistent angle. Some spots getting sharper while others aren't or asymmetrical angles or an unseen micro-bevel on one side cause rapid burr formation but difficult removal. A lot of newer production knives like ZT are using thicker blades with more obtuse angles which means more steel to remove when sharpening, while a lot of cheap gas station type knives are using thinner blade stock to save money which incidentally makes for a quicker job of sharpening.

I do feel a little redundant typing all this after what David posted though. Just thought i would throw out some info.
 
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