Blade steel question. Bend or break?

clampdaddy

clampdaddy

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Aug 31, 2013
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Ever since I snapped the tip off of my grandpa's favorite pocket knife when I was a kid I've had almost a phobia about breaking the tips off of my knives. Im about as far from a metalurgist as it gets so i was wondering, are there steels that stand out as having higher levels of strength when it comes to lateral force being applied to it or is it more the heat treat itself? My edc is a spyderco endura 4 wave. How good is VG10 compared to others in this regard?
 
I am very paranoid of that as well, so i use the right tool for the job. Yes the type of steel plays a role in the amount of stress it will take. Another factor is the heat treat and the way it is heat treated. The other factor is the geometry of the blade. These 3 factors make up every characteristic a blade has, excluding the skill of the maker. Most large knives will bend while most kitchen and pocket knives will be more prone to breaking. I feel the best piece of knowledge over all of this is to use the proper tool.
 
I very rarely do any kind of prying unless I can really get in there and use a thicker part of the blade. Usually it's to get out a slotted head screw, where I try to use the spine. Always leary of it though.
 
All steels have (at least) 2 major properties that are important in knife making.

You will see these properties described in different ways...strength, toughness, durability, hardness...and lots of other words used to describe the 2 basic qualities that matter most.

I will call them Edge Retention & Toughness.

Edge retention is how you describe how long your blade will remain sharp. Achieving really great edge retention generally requires the metal to be relatively hard, and harder almost always means more brittle. Usually the harder a metal is the more prone to chipping and breaking it will be (this is a simplified explanation as there are other factors as well but it will help you with what you want to know nonetheless). The high end stainless steels for knives these days have some of the best edge holding capabilities, but they are not for prying. (really no knife is..but that's a separate conversation)

Toughness is how you describe lateral strength and the blade's ability to resist chipping and breaking. More malleable ("softer") metals are likely to bend or edge-roll before they break or chip. Generally speaking the high-carbon steels are best suited for this "toughness". For example ESEE will sell you a 1095 carbon steel knife and tell you that if you break the tip off they'll replace it with a new one no questions asked. High carbon steels often do not hold an edge like a high-end stainless but they are also easier to sharpen yourself.

Metals side, as asdf12345 said the thinness or thickness of the tip matters, of course. From a design perspective, you could get a thick tanto blade in a high quality stainless and probably never break it. Similarly, I suppose you could also get a thin high carbon blade a break it relatively easily. So design matters as much as the type of steel you use.

If the concern about breaking a tip if important to you I would suggest a good carbon steel and a design that includes a robust tip. These among others are very tough high carbon steel choices that I would personally suggest....1095, ZDP-189, PSF27, M4, 3V, and 4V.

I have to say..knives are for cutting and they break when they are used for prying. If you are going to use a knife for prying it HAS to be one designed to handle that abuse and you're usually going to pay a lot for that luxury and end up with a knife that also doesn't slice very well. My best advise is use a pry-bar for prying and a knife for cutting.

Best of luck to you in your search!
 
I like a thin tip because it is so useful for detail work. Thick tips are just clumsy. But I also carry a mini prybar on my keychain.

As for steels, what you're looking for is toughness. In non-stainless, 3V has excellent toughness. In stainless, Elmax is about as tough as it gets.
 
How come no ever complains about the fact that crowbars and wrenches and screwdrivers and pliers and hammers don't cut worth a hoot? :rolleyes: :D

No need to over-complicate things... If you're don't want to break a knife's tip, stop prying stuff and turning screws with it. Buy a handy pocket-pry-bar and/or keep a cheap screwdriver or a good multi-tool handy.

Strength is resistance to deformation (edges wearing flat or rolling over). Toughness is resistance to breaking (chips in the edge or busting off a tip). They are not necessarily mutually exclusive.

Bend or break? Neither. A knife that flexes and stays bent is simply too soft. Flexibility is a function of geometry; under the same amount of stress, a thinner blade will flex more than a thicker one, regardless of hardness. (No one wants to believe that part until you show them a nice thin filet/boning knife made of stainless at 60Rc+ that flexes well without breaking, and springs back to true when the pressure is released).
 
james terrio said:
How come no ever complains about the fact that crowbars and wrenches and screwdrivers and pliers and hammers don't cut worth a hoot? :rolleyes: :D

No need to over-complicate things... If you're don't want to break a knife's tip, stop prying stuff and turning screws with it. Buy a handy pocket-pry-bar and/or keep a cheap screwdriver or a good multi-tool handy.

Strength is resistance to deformation (edges wearing flat or rolling over). Toughness is resistance to breaking (chips in the edge or busting off a tip). They are not necessarily mutually exclusive.

Bend or break? Neither. A knife that flexes and stays bent is simply too soft. Flexibility is a function of geometry; under the same amount of stress, a thinner blade will flex more than a thicker one, regardless of hardness. (No one wants to believe that part until you show them a nice thin filet/boning knife made of stainless at 60Rc+ that flexes well without breaking, and springs back to true when the pressure is released).
Click to expand...

Mine cuts just fine James.
 
james terrio said:
No need to over-complicate things... If you're don't want to break a knife's tip, stop prying stuff and turning screws with it. Buy a handy pocket-pry-bar and/or keep a cheap screwdriver or a good multi-tool handy.
Click to expand...

I tend to agree with that. I'm OK with random light prying using a knife, but to get out a screw, I'll use my Skeletool that I keep clipped to my LFP. Handly little thing!
 
james terrio said:
Flexibility is a function of geometry; under the same amount of stress, a thinner blade will flex more than a thicker one, regardless of hardness. (No one wants to believe that part until you show them a nice thin filet/boning knife made of stainless at 60Rc+ that flexes well without breaking, and springs back to true when the pressure is released).
Click to expand...


The stiffness of steel, or any elastic material, is represented by a property called the "modulus of elasticity", or "Young's modulus". This property is mostly unaffected by slight alloying of steel or different strengths or different hardness or different heat treats. This is the science behind what you are saying and why what you are saying is true.
 
This only reminds me how much I like the pry handles on my DPx HEST fixed blades. I'm sure that little pry bar has saved my tips many times. One of the finest things designed into a knife I have ever seen. Very useful.
 
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