Rockwell hardness and edge holding.....

[lonestar1979]

The higher the blade is on Rockwell scale,the better edge holding should be....Is this statement always true?I am talking about the blades made of same type of steel and grind.All experiences welcome!

 

[Mo2]

Not always true. It's a good general rule. I would not look at a chart of hrc numbers and think the best edge holding is the highest number. Though that absolutely could be the case.

Check out some of these channels with tests showing some higher hrc knives did more poor than the lower hrc knives and visa versa.

Supersteel steve
https://www.youtube.com/channel/UC76o8bpHyEpBaysM9Pr83Og

Outpost 76
https://www.youtube.com/channel/UCI_ZXbN06A7W937hKKnUfqQ

Tomhosang
https://www.youtube.com/channel/UC1JQejhMkEMql-kh0ZqLZJg

How the heat treatment was done matters more than the hrc value itself. Those with ln2 cryo also cut more regardless of hrc.

Alot of the knives tested on those channels are also on this list
https://docs.google.com/spreadsheets/d/1OepNr_D4lqbdTFqdqWl1rmAd4bOzPzJe6J0iEWrdJGU/htmlview

@DeadboxHero does a lot of geometry and toughness testing.
https://www.youtube.com/user/shawnhouston

 

[Gvard]

In general, yes. higher hardness = higher abrasion resistance and better edge stability (less likely to roll). Although it increases the chances of chipping, which leaves you with dull spots. That's why it's important to choose the right steel, grind and hardness combination for the type of tool you're using and your particular way of using the tool for best performance.

 

[Mr.Wizard]

Which kind of edge holding? Toughness, wear resistance, or edge stability?

 

[Obsessed with Edges]

Too-high HRC for a given steel just means it'll chip or break much too easily, becoming too brittle. So, it's not a given that 'harder is better' for edge-holding. Too hard & brittle, and a fine edge just chips or crumbles away. Too soft, and it rolls or dents too easily. Every steel has it's limits for it's 'best' attainable hardness while also keeping within reasonable limits for toughness (resistance to breaking). There's almost always a trade-off between toughness and hardness, and smart makers will bias it one way or the other, depending on what the expected uses are for the blade.

I think, for the vast majority of knife steels, good hardness for edge-holding's sake usually falls in the HRC 57-61 range with relatively little danger of breakage, unless they're abused or if the heat treat & tempering is botched.

 

[lonestar1979]

Heat treat is everything,have seen some of videos above,wish there was more simple carbon steels like 1095 in rc61-3,or aebl at same rockwell in factory knives.

 

[Mo2]

Heat treat is everything,have seen some of videos above,wish there was more simple carbon steels like 1095 in rc61-3,or aebl at same rockwell in factory knives.

https://knifesteelnerds.com

Good site wrote up by Larrin and has many contributions from others in the industry. He has an article on aebl and possibly on 1095? I forget. They are not much for edge retention overall but decent all around steel, especially aebl with high toughness.

I've seen some 1095 at 61rc on ebay, they are usually really bad junk with incorrect heat treatments.

 

[Larrin]

I wrote a little article about what rockwell hardness tells you and what it doesn't here: https://knifesteelnerds.com/2018/11/12/rockwell-hardness/

 

[Wowbagger]

I think every one here has told you the facts and what is important.
I've always said I have never met a knife that was too hard and that I would like to.
Micro cracking comes into play at some point so it's not just a matter of making the thing as hard as possible.
For plain high carbon knives I never shy away from the ones on the higher end of the scale; 64 , 65, 66 if I could find it.

Some of the complex super steels perform better down around 61, 62.
One of my favorite super steels is ZDP-189 and they run that stuff 65 or 66.
It'll chip though. That's fine with me I'll trade a bit of chippiness for some extra hardness

One shouldn't even think of throwing or beating on a knife on the higher end of the scale though. That's a recipe for disappointment (broken blade).

Finally I'm sure in the links above there are excellent explanations of the difference between very hard CARBIDES verses very hard plain high carbon steel. Those are two VERY different things in deed.