Don't understand Titanium-Help Please

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I don't really understand Titanium. If it's lighter than aluminum but stronger than steel then why isn't it used for blades. I've also seen somewhere that there is a knife with a Titanium blade (I think) but then I've read where it's too soft. I don't understand. Why are handles made of Titanium? Would steel be stronger but heavier but just heavier or is Titanium really stronger? I'm sure someone can explain it and I thank you in advance. Dave
 
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Dave,

Mission is well known for their Titanium knives. I should note that I am a Mission dealer so, factor in any bias you care to.

First, Titanium is not as heavy as steel so, it is not the best chopper in the world.

Second, Titanium may withstand structural forces that would cause a steel to break, it still is softer then most steels so the edge will wear faster.

Third, it will not rust. Period. No dulling of the edge to corrosion either.

Fourth, it has special properities that appeal to the EOD crowd. I'll leave that topic to someone more qualified then I.

The things I like best about Titanium (whether in knives or eye glass frames) are the "memory", the corrosion resistance and, the absolute strength against out right breakage.

I tend to view Titanium knives as a specialized knife, similar to ceramic knives such those offered by Mad Dog and Boker. Becuase of their special properities they have a strong appeal in certain specialized applications and, will find good service in other more main stream uses as well even though cheaper alternatives are available that will give the same level of performance. You also have the gadget/neato/Rambo factor with a Titanium knife that is much harder to get with a plain old carbon steel knife
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Stay Sharp,
Sid


[This message has been edited by Sid Post (edited 11-07-2000).]
 
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Thank you Sid. That helps but are handles made of Titanium actually stronger than ones made of steel given that all dimensions would be same? Thanks, Dave
 
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Titanium is not stronger than steel. Its strength to weight ratio is higher than steel which is part of what makes it a desirable material for linerlocks and frame locks. Its very wear resistant under most circumstances, won't rust, and is non magnetic.It has good memory in terms of retaining its shape, and is rather springy.
The reason its not used for general purpose blades is it doesn't hold an edge or take to good of one. It can't be hardened enough to make it hold an edge like steel can. I think RC testing will yield in the 40's usually. And it doesn't have any carbide matrix or cobalt particles in it like talonite to provide wear resistance. Some companies have taken to adding tungsten carbide and other things to the alloy that improve its edge holding in their knives, but it still won't perform like steel.
It has has a high friction coefficient with steel which means that a titanium locking liner against a steel blade will be less likely to slip than a steel liner against a steel blade.
It also resists denting. Its pretty much impossible to forge titanium, its not malleable at all. It holds its shape until you beat on it so hard that it crumbles. So folder parts made out of titanium don't get dented or flattened out. A locking liner won't get its end smashed in by the tang and cause blade play.
This is all from memory of threads I read about Ti here on BF. If I got anything wrong please correct me. Otherwise I hope that helps answer your question.

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Aluminum is lighter than titanium.

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Carlos

[This message has been edited by Carlos (edited 11-07-2000).]
 

Cliff Stamp

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Matt :

it doesn't hold an edge or take to good of one

There are people who can get Missions Ti sharp enough to easily shave and/or do any other cutting chore. It however is not steel and you need to handle the sharpening differently. Will Kwan would be one to ask if you are having problems.

In regards to edge retention, if you are cutting something where blunting is due to rolling then Ti will blunt quite quickly compared to steel which is much stronger. However not all blunting is caused by rolling and the higher ductility of Ti and impact toughness could easily give it better edge holding in many materials.

For example, in cutting carpet the CPM-420V blade I have from Phil Wilson at 59 RC takes edge damage by chipping whereas my INFI Battle Mistress at 58-60 RC resists fracture. After a session of cutting the BM can be steeled back to 100%, the 420V blade needs the chips hones out. The BM easily has the better edge retention even though 420V is stronger and more wear resistant.

-Cliff
 

Bronco

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Walt,
Thanks for the link to that Swordforums article. I've had it bookmarked for awhile now, and like to refer to it from time to time as it's an excellent overview of the general properties of titanium. I think it's safe to say that, although certain titanium blades do fill a particular niche quite well, it's going to be a long time before steel is in any danger of being completely replaced by Ti. I do have a problem with this article, however, in that only one paragraph of the 23 total paragraphs makes any meaningful reference to beta alloy titanium (the only type of titanium truly suitable for serious use cutlery).

The authors didn't bother to waste anybody's time evaluating 4140 as a blade steel, yet all of their conclusions regarding the suitability of titanium as a blade material are drawn from an analysis of the properties of alpha alloy titanium (which is essentially the titanium equivalent of 4140 steel). I'm not trying to split hairs here, but I really believe we'd be better served if the authors were to promote a similar discussion focusing instead on the properties of beta titanium (cost and availability issues notwithstanding).
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-Bill
 
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I guess maybe I didn't pose my question properly. What I was really concerned with the the use of titanium as a handle material. In this particular use, is it as strong or stronger than steel? I'm concerned with how well it will hold up when stressed. Sorry for the confusion, Dave

BTW- I'm speaking in reference to folders.

[This message has been edited by Dave Costin (edited 11-08-2000).]
 
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Dave,

I'm pretty sure that on a well built Ti handle knife, the pivot pin and/or the stop find will shear before the Ti. handle slabs. One shining example of a Ti. handled knife is the Sebenza. I'm pretty sure that a human could not break the handles under normal use. If you were planning on planting a small explosive between the slabs, they might not survive
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Not a very scientific answer, but I think I answered your question.

~Mitch


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Bronco

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Dave,
To put it in the simplest terms, if you have two otherwise identical liner lock folders, one with .010" thick titanium liners and one with .010" thick steel liners, the one with the steel liners will be stronger. For equal volumes of material, steel is stronger than Ti.

What will happen quite often, however, is that the manufacturer will take advantage of the lightweight characteristics of Ti and produce a liner thicker than what would be practical with steel. This illustrates the fact that Ti has a greater strength to weight ratio than steel.

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Semper Fi

-Bill
 
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OK, That helps. Thank you. Dave

BTW, I think there are a lot of advertisements that are misleading. Can't recall where I've seen it but I know I've read that Titanium is stronger than steel. I had a hard time believing it which is why I asked. I knew I get a correct answer here!

Thanks again, Dave
 
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Theres other factors involved to. Ti has a good memory in terms of shape without being heat treated, which makes it ideal for springs. It won't weaken over time. It also won't dent, you'll be less likely to deform the end of the liner under heavy use. Actually I'd say you couldn't, its probably not that big of a deal with steel either, but less likely with the ti.
And if you were realy going to give the handle on a liner lock hell, the titanium won't get bent. It may flex, but it should spring back to its normal shape once the stress is removed whereas a steel liner or handle could stay bent.
Because its lighter, thicker peices can be used. So in the case of a liner lock, ti allows for thicker liner which is stiffer than liner made out of thin steel.

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It'll feel better when it stops hurting.
 
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