Toughness? Strength? Hardness? Edge holding ability?

[bigoledude]

When cleaning large redfish, large black drum and bigole catfish, I use a butt-ugly blade like the Dexter-Russell 6-inch Beef Skinner. At first I hated the look of this knife, but because of how well it handles on these larger fish, I have developed a great fondness for this style.

This will probably be the first blade I build once I practice on many mild steel and inexpensive steels. And, once I am comfortable with my success at heat treating.

Y'alls terminology still confuses me. "Strength" seems to be one of the attributes I would need since the rib bones have created "dents" in my cheaper knives. Edge holding ability would be nice so I won't have to stop and straighten my edge as often. "Toughness" seems to indicate soft. I can't imagine how I could benefit from soft.

My goal would be a knife that could handle the meat-cutting of the filet process AND also the rib-popping portion of the job, without having to switch knives mid fish.

Is/are there steels that would be a good choice for this difficult task? I'm not particularly worried about "staining" since I take good care of my knives. Especially if it is my first real-deal handmade creation.

 

[Frank Niro]

Big fish require bigger knives. I believe almost all the steels, both carbon and stainless will do a great job for you. Yes, I have made large one for large fish in the past, and just completed a folding fish knife that is proving to be good as well. Frank

 

[Stacy E. Apelt - Bladesmith]

The terms use vary a lot, and some don't have real definitions. Here are how I would explain some in simple terms:

Strength is mainly a factor of thickness and width. A "strong" blade will be better for rougher use. It deals mainly with blade breakage risk.
Edge holding is how long the edge lasts between sharpening. It is a factor of both hardness being just right (not too hard or too soft) and the steel's alloying. It covers the edge rolling and chipping, as well as wearing down. Proper HT for the steel chosen is a big factor here.
Wear resistance sounds like edge holding, but is specifically related to the edge wearing down through abrasion. It is mostly a factor of the steel chosen. As always, HT needs to be right, too.
Flexibility is merely a factor of thinness and taper. It has nothing to do with hardness or HT.

All the above can mostly be dealt with by proper knife geometry and picking the right steel for the use desired.


Toughness is the big factor when planning a knife. It is a specific term as well as a general term that encompasses many of the above qualities. The steel type is what determines toughness to the major part. A proper HT and tempering is also important. The alloying in the steel will make some tougher than others and some harder than others. Picking the right balance is critical. Steels like 3V and such are really tough. Steels like M4 can be really hard. Steels like 1084 will be good beginner steels, as they are reasonably tough, reasonable hard, and reasonable easy to HT. 5160 is tougher for the new maker, and 1095 is harder.
I recommend 1084 for basic carbon steel blades, and CPM-S35VN for stain less blade. I make a lot of large fillet blades in S-35VN.

All these terms have specific metallurgy definitions, and are determined in specific tests with metallurgical machines ( Rockwell, Charpy, etc.)....but in knives, most of these terms are generalized and determined by use, or by use based testing ( cutting, chopping, slicing, etc.)

Final comment. HT is where it all happens ( except for flexibility). The greatest steel in the world ( Cowry X for example) will make a bad knife with a bad HT. The simplest steel in the world (1084) will make a great knife with a great HT ( and with 1084 it is pretty easy to get a great HT).

 

[Cody Hofsommer]

In my eyes, tough and hard are on opposite ends of the spectrum. If a blade is too hard, it will chip, which makes it dull, if a blade is too tough, it will roll, which makes it dull. Somewhere inbetween is what we want. What the blade is intended for determines where in the spectrum it lands. A sword need not be all that hard, but must be very tough. A straight razor needs to be hard, and because it won't see lateral loads, need not be so tough. This might be an over simpalazition, but gives the idea of tough and hard.

Any everything that Stacy said!