# Difficulty sharpening 440C



## johnstoc (Dec 14, 2014)

In the last year I've become proficient with double bevel sharpening thanks to this forum and Jon's videos. I have consistently had more trouble sharpening one knife which is 440C, its a Gunter Wilhelm 8" chef. In particular, detecting a burr is difficult or impossible so I feel like I'm guessing. Sometimes I'll get a good edge (shaves hair and cuts newspaper) off a 6k stone, sometimes the edge is garbage. 

Do others have this issue? Is the abrasion resistance of 440C the issue (I've seen reference to this for machining and bearing manufacture)?

My setup is a gesshin 400 and 2k, king 6k. All of my other steels (victorinox forschner, Mac Pro, gesshin Ginga and gonbei, cheap carbon Nakiri) I don't have issue with. The knife feels and sounds hard and "glass like) on the stones, almost with a resonance that rings or zings as you move it. I know it's removing metal due to the dark swarf and I can see a clean new bevel is cut on the knife. I have a similar experience with a cutco 440A knife but not as bad.

Would appreciate any tips or thoughts from fellow KKF folks!


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## JBroida (Dec 14, 2014)

soft steel like that can be gummy feeling and burr development and removal can be harder, so even though it may be easier to remove steel, its not as easy to get a nice edge.


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## Sabaki (Dec 15, 2014)

When began 440c to be a soft steel?

C 0.95-1.2%
Cr 16-18%
Mo 0.75%

Even at 58Hrc it's still packed with large Carbon and Cromiumkarbides, some Molybdenkarbides as well so i wouldnt consider 440c to be a "soft steel"

440A is slightly softer and better due to a little less Carbon but it also has the same amount of Cr and Mo.

440 is not that easy to sharpen in my opinion


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## JBroida (Dec 15, 2014)

The way it is often heat treated, especially in the knife he is talking about, is on the much softer side for that steel. There are better HT's of 440c, but the knife in question is not one of them.


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## gman (Dec 15, 2014)

i asked about 440a a while ago. i was having a similar issue of having a hard time getting a burr. the advice i got was to start with a 220 wet/dry automotive sandpaper, and to use light pressure. worked like magic.


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## Sabaki (Dec 15, 2014)

i searched for the knife he mention and came up with this steel: X50CrMoV15 wich is very far from 440C
typical German kitchen steel hardened to about 54-56Hrc so it's pretty soft!

http://gunterwilhelm.com/our_brand_and_steel

I've sharpened a couple in this type of steel using my belt grinder and would not recommend any higher grit then 1000-1500 for wetstones


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## psfred (Dec 15, 2014)

That particular knife will sharpen much better if you use something between the 400 and the 2000 grit, I use a coarse stone to fix them when really dull, but sharpen on a Bester 1200, finish on a synthetic blue aoto, and then strop on chromium oxide.

Something like a Bester 1000 or King 1000 will work better for you, just sharpen on the 1000, polish a bit on the 2000, and strop.

They do not de-burr well at all, you can get a big floppy burr that won't come off easily, and a fine edge from high grit stones is pointless as the carbides are large and very hard, so they tear out, leaving the soft matrix for an edge. Folds over the first time it touches anything hard (like a cutting board). A "toothy" edge from a 1000 grit stone with some stropping on a fine stone or strop loaded with something like chromium oxide will work nicely. 

Still won't hold an edge very long, but it will be sharp.

As far as 440C (which is indeed similar when heat treated the way it usually is for kitchen knives) a similar sharpening system works well. I can get mine pretty sharp, but the edges just fade away quickly. There is no reason to use high grit stones with 440C unless it's RC 60 or better.

Peter


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## johnstoc (Dec 15, 2014)

Thanks all for the info. I appreciate it and am just seeking to understand more about different knives, different steels, and how they take and hold an edge.This is one of my beater knives, used to cut frozen things or for other folks to use so I don't have to worry about them destroying the good ones. 

Sabaki - you're correct that GW now states X50CrMoV15 on their website. They have changed their story! The knife I have is laser etched with "440" and all of their marketing literature used to claim "440 High Carbon Stainless" while talking up how great it was. I'm not sure how they cram X50CrMoV15 and "high carbon" into the same sentence when High Carbon is defined as >0.9% Carbon (ASTM 304) and X50CrMoV15 is 0.5%, maybe half of 440C on a good day. Now I wonder what steel it really is... I design steel castings and we have a mass spectrometer and hardness tester at work, I just need to convince someone to run it for me :scratchhead:

I'll reserve my judgement on the sharpenability and other characteristics of 440 steels for now.

Again, thanks!


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## gic (Dec 15, 2014)

Crappy overpriced stuff. I see them at a Costco roadshow from time to time and wonder what the point is since one can go down the aisle and get the Tramontina Pro victorinox clones with OK steel and good geometry (if you like big bellies of course) for 1/10th the price


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## Dave Martell (Dec 16, 2014)

Over the years I've come to understand that when I see "440" as the steel being advertised it really means 440A. When it's 440C it'll say "440C".


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## Mr.Wizard (Dec 16, 2014)

Dave Martell said:


> Over the years I've come to understand that when I see "440" as the steel being advertised it really means 440A. When it's 440C it'll say "440C".



You should consider compiling a list if little nuggets like this if you haven't already.

(By the way do you have any suggestions for how I can make my logarithmic grit chart more useful to this community?)


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## Sabaki (Dec 16, 2014)

Dave Martell said:


> Over the years I've come to understand that when I see "440" as the steel being advertised it really means 440A. When it's 440C it'll say "440C".



makes sense :thumbsup:


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## johnstoc (Dec 17, 2014)

I misspoke before, the knife actually says 440C on it. 

That said, I totally agree with Dave that 440=440A and that any maker would be sure to make it clear if they use the more expensive 440C.


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## Benuser (Dec 17, 2014)

Strange. The 440C I have sharpened were very easy, almost carbon-like. Something must have gone very wrong with the HT.


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## masibu (Dec 17, 2014)

There could be so many variables here but assuming this is a soft version of 440c you're just not going to get good results nearly as easily as you would anything a bit on the harder side. I don't know about the geometry of the blade and how thick it is behind the edge either. With softer stainless, as has been mentioned before, a lower grit finishing stone is more ideal a finish than going to a higher one. More importantly though is making sure you're deburring properly, which can be painful for these kinds of knives. I would sharpen as you would normally and deburr at a higher angle just as you would do with microbevels. raise the spine of the knife about 20mm off the stone at the heel and use really light pressure so that you're basically "scraping" the residual burr off the knife on either side.

I personally use a bester 500 to raise a burr on soft stainless and then use a 1200 sigma power to deburr using the same technique I just mentioned and it seems to work well enough. In your case, I would use the 400 to raise a burr and try deburring on the 2000 stone instead.


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## Dave Martell (Dec 17, 2014)

Based on the maker I'm going to assume the knife to be on the soft side on the heat treat. Combine that with it's thick geometry and I can see how this knife could be a chore to sharpen, specifically de-burr, effectively. This knife is the reason why professional sharpeners have belt grinders.


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## psfred (Dec 18, 2014)

Could also be very thick behind the edge as well, so even if very sharp will cut poorly in firm or hard materials due to the thick blade wedging badly

I always find it curious that so many "chef endorsed" knives are so bad. One would think that a professional wouldn't put their name on low quality goods. Either that to they really don't know what a good knife is!

If you don't mind the effect, take a close look at that knife and consider thinning it somewhat ( or a lot) behind the edge. It will show, since you are probably going to have to remove quite a bit of metal, but it will cut much better.

Peter


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## rick alen (Dec 26, 2014)

I have a Randall knife in stainless, which I understand is made alternatively from 440b or c. I understand the temper to be for ruggedness rather than full hard. It sharpens beautifully on a cheap 1/6K waterstone and finished on a fine Ark. But it is a fully forged blade and I believe Randall does not skimp at all on the HT.


Rick


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## Roger (Dec 27, 2014)

I used to do it on my J-stones but now I like to use a stone especially made for stainless steels, it really helps with difficult to work with knifes, the kind with a burr that likes to stay here flipping back and forth.

I use the Missarka combination stone after the atoma 140, one side is silicone carbide, the other an abrasive especially made for stainless that does not clog. It's definitely not a fine stone but it makes a great edge that lasts and is more usable for not so hard stainless.

When you have a nightmare inducing burr that doesn't want to get out of here, you can put a piece of wet sandpaper around 800 grit on a piece of cloth sitting on a flat surface and strop your knife on that. Really helps with tricky to finish knifes, it gives a longer lasting edge.


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