Knife and Sharpening Steel Hardness

A quick analysis of the knife and the Sharpening Steel Hardness

Surface hardness of sharpening steel hardness products through a quick test is used to ensure the quality of the properties to determine the appropriate heat treatment has been achieved. Surface hardness can also be used as a component of a process of reverse engineering to determine the relative quality of a product is known and to determine the steel grade and heat treatment. In this case, we have tested eight of the year dao manufacturer of carbon steel and stainless steel and sharpening steel four to compare the relative hardness and provide insight into the operation of the knife.

Knife and Sharpening Steel Hardness
Knife and Sharpening Steel Hardness

Rockwell C hardness (HRC) is the typical hardness scale used to through the hard steel products. When tested HRC did not leave a noticeable indent in the surface of the test, Rockwell 15n (HR15N) scale was chosen to perform the test with the results converted to HRC. Scale 15n is the lightest of the tests and indented surface hardness is hardly noticeable.

Hardness testing of different metals can be compared as long as the metal is relatively tight in physics and engineering. Thus, comparing the hardness of the hard carbon steel plate and stainless steel hardware is usually acceptable. To do a full analysis of metallurgical and chemical composition micrographic analysis should also be used. However, both these tests (usually) destruction in nature and I do not want to destroy my knife.

Table 1 – Selected Knife and Sharpening Steel Hardness

Hardness, HR15N
KnifeSteel Type123Avg.Equivalent HRC
Wusthof Classic ParingSS88.288.888.388.456.5
Wusthof Dreizack ParingSS87.587.187.387.354.1
Sabatier 4-Star 10-in. Chef’sCS88.889.289.989.358.3
Sabatier 4-Star 14-in. Chef’sCS80.379.279.479.637.8
Sabatier Two Lions CleaverSS83.484.183.883.846.6
Sabatier 4-Star 6-in. Nogent SlicerSS84.184.183.984.047.1
Hoffritz (Henckel’s) 8-in. Chef’sSS84.785.087.785.850.9
Anton-Wingen Othello SlicerSS81.980.681.981.541.7
Sharpening Steel Hardness12345Avg.Equivalent HRC
F. Dick91.291.691.

All testing was forged steel knives with the exception of Wusthof and Sabatier Two Lions Dreizack stamped steel. All are stainless steel with the exception of two knives Sabatier chef’s 4 star carbon steel. Steel grinding chemicals are unknown, but it is guessed that Hoffman and F. Dick is almost certainly Wusthof and Sabatier carbon steel and stainless steel can be.

By convention, hardness testing is usually done in groups of three or more with the average results. Many enema is performed on steel grinding because there seems to be a bit bigger changes may be due to the vertical striations (grooves) are found in steel grinding.

A note must be made relevant to different testing and knife sharpening steel. For knife, Sabatier Nogent is brand new; the Wusthofs is relatively new (probably less than 5 years); the 4-star Sabatier 10-in. at least 30 years old (maybe even older), the 4-star Sabatier 14-in. and Hoffritz is probably 20 years old; and Sabatier Cleaver and Anton-Wingen, Bas-Rhin is probably 30 years old. For Sharpening Steel Hardness, the Sabatier is brand new; the Wusthof is probably less than 5 years old; F. Dick and Hoffman both steel and at least 40 years old (possibly larger).

The most interesting aspect of the experiment is a big change between the knife and the lack of variation between steel grinding hardness. A complete metallurgical analysis will be able to determine why this is the case, but as stated before, this has not been done. Also related is the hardest knife carbon steel and is the oldest knife tested (10-in. Sabatier), while the most difficult is the old medium carbon steel 14-in. chef’s knife. Anecdotes, both knives are relatively easy to sharpen (this is one of the attributes of carbon steel), and 10-in. does not appear as the best master of a knife edge of all that I have (probably by the Hoffritz). The hardest knife to sharpen as the Nogent, the knife, and Anton-Wingen, Bas-Rhin. This is not surprising as they are all stainless steel and toughness of stainless intrinsic This led to a knife that is more difficult to sharpen. Also, they do not appear to hold an edge at 10-in. Chefs, the Hoffritz, or Wusthofs.

Higher hardness does not mean that a knife is better. What it means is through proper grinding, you will be able to achieve a better edge, but it will be more difficult to sharpen a knife rather than less hard. Depending on the chemistry of the knife, stainless steel should hold an edge longer than when it is harder than carbon steel, that is less susceptible to wear off. However, according to my experience with the toughness test I do not believe the tests typical toughness (eg Charpy impact test) is equivalent to the type of wear that experienced knife. An experiment that will be good for checking the edge of a knife after grinding and honing appropriate by scanning electron microscope (SEM) to establish an initial condition, then take the knife to some sort of sliced or cut repetitive regimen and check with a regular SEM. So you can build a history of the next cycle distortion compared to the cutting board, thus determining the knife (Steel) held its advantages are best.

The hardness of steel grinding relative to the knife indicating that perhaps some of knife grinding away on whatever hardware is less than I used steel. It also indicates that, at least from the hardware perspective, it’s not really important that I use steel. What is perhaps more important is the surface roughness of steel (which can not be measured), and that, along with the geometry of the striations, can affect the final quality of the knife edge. Microphotography of the blade before and after steeling will be a good test to determine the most efficient steel deburring and rearranged at the edges.

On November 08, 2007 PaulR (guest) said…
Subject: Steel and steels

Toughness in knife steel corresponds to resistance to chipping, not to edge holding. This is why your carbon steel knives hold edges longer. The harder Sabatier should an edge much longer than the stainless knives, even if sharpened to a more accute bevel angle. It would also probably be more fragile … better suited to fine slicing than to hacking up chickens and pineapples.

Ease of sharpening is hard to correlate to either hardness or toughness (there are some hard and tough steels that sharpen pretty easily, and some that fight you every step of the way). I’m not sure what physical qualities equate to sharpenability, but, subjectively they’re easy to feel. Some stainless steels feel “gummy.” Some might be too springy… the edges seem to flex when you try to grind them on a stone.

Something that contributes to steel’s abilty to take a very fine edge is carbide size, which is determined by the alloy, and possibly heat treatment. Smaller carbides allow for a finer, more stable edge. Carbon steels tend to have much smaller carbides than stainless steels, but some of the newer “super steels” that you see in expensive Japanese and custom knives come close.

On September 19, 2008 RMC (guest) said…
Subject: Work Hardening

Will work hardening have a noticeable impact on knives that have seen more than their fair share of kitchen action?

No. You would have to bend or otherwise deform the metal – repeatedly – to such an extent that the knife would be useless before it work hardens. Just abusing it in the normal way (dishwasher, banging into other metal objects, etc.) won’t accomplish any metalurgical changes.

Here’s how to observe true work hardening: take a section of soft copper tubing – the kind used for plumbing – and coil it up tightly, perhaps around a stick or something. Now try to uncoil it. Seems much stiffer now? Has a tendency to kink? This is work hardening. The way to reverse this is to anneal the copper (heating it to dull red and letting it cool off in still air). One anealed it’s soft again.

The only possible metalurgical issue I can imagine besides rust or staining that might affect kitchen knives is chloride stress corrosion cracking in stainless knives. I suppose if you immersed your 300-series stainless knife in a bucket of chlorine bleach and put some tension on the knife, after a while the kinfe would crack. So… don’t do this and you’ll be fine.

I’ve inherited a 60 year old carving knife that was rusty and quite abused. It’s now the sharpest knife I own – shaving sharp – and hasn’t work-hardened.

Thanks for watching!

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