Knife Edge Toughness Tests

[Larrin]

I wrote an article about the published quantitative tests for knife edge deformation and chipping. There are plenty of people out there chopping into wood, bricks, etc but what is out there in terms of a repeatable test? Can charpy impact and other toughness tests be related to edges of knives? Is there any point in doing toughness testing for knives that are designed only for cutting and not hard use?

https://knifesteelnerds.com/2018/08/13/ ... toughness/

[dj moonbat]

I wrote an article about the published quantitative tests for knife edge deformation and chipping. There are plenty of people out there chopping into wood, bricks, etc but what is out there in terms of a repeatable test? Can charpy impact and other toughness tests be related to edges of knives? Is there any point in doing toughness testing for knives that are designed only for cutting and not hard use?

https://knifesteelnerds.com/2018/08/13/ ... toughness/

It's always seemed to me--and you'd be a good person to correct me if I'm wrong--that toughness necessarily involves a measure of ductility that carries over into other aspects of a steel's behavior. Like how burrs form, how easy or difficult they are to deburr, whether you can strop/steel an edge back into useful condition easily, whether they chip or roll under stress, etc. I'm not interested in whether I can chop into logs with a knife, but I've found that knives that are made of tough steels tend to do well at these other things that I am interested in.

[Larrin]

Deburring is often easier with brittle steels because the burr fractures off easily. As I said in the article, toughness is important even in fine cutting knives because if the edge is thin enough it will lose sharpness due to chipping or rolling.

[bearfacedkiller]

I have been thinking about how toughness effects edge retention for a long time. It seems as though many people are hung up on abrasive wear resistance/carbide volume as well as hardness as the measures of edge retention. At the same time people refer to these high carbide steels at high hardness as chippy. It would seem as though under certain conditions that microchipping could very well be the mechanism causing dulling. I wonder how toughness really comes into play and look forward to any insight you can give on that in the future. We have had it come up on the forum a few times but the discussion didn’t really go very far.

As always Larrin it is much appreciated that you share your knowledge with us.

[MichaelScott]

I don’t have anything to add since I am a steel novice, but I am avidly following this discussion.

[Larrin]

I have been thinking about how toughness effects edge retention for a long time. It seems as though many people are hung up on abrasive wear resistance/carbide volume as well as hardness as the measures of edge retention. At the same time people refer to these high carbide steels at high hardness as chippy. It would seem as though under certain conditions that microchipping could very well be the mechanism causing dulling. I wonder how toughness really comes into play and look forward to any insight you can give on that in the future. We have had it come up on the forum a few times but the discussion didn’t really go very far.

As always Larrin it is much appreciated that you share your knowledge with us.

If I can find the answers I will definitely share them. :)