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(noob question) confusion of titanium


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almost everyone treats titanium as the strongest metal ever but from what i understand its 2 to 4 times stronger then steel wheras mertenste is about 5 times stronger. (or maybe just harder) im just curious why no one has tryed to use it more for blades if it is that strong untreated.

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Strong and hard are two different properties. Carbon fiber is much stronger than steel, by weight, and in certain ways. However, it's less stiff for a given cross section and it won't hold an edge. The same is true of Ti. It's lighter than steel, for a given amount of material, but it's not as hard, or not hard in the same ways as steel, It also doesn't have the abrasion resistance of blade steels.

 

A knife blade needs certain properties. Hardness, toughness, abrasion resistance, shear strength, torsional strength, impact resistance, compressive resistance, and I'm betting that there are other properties I haven't thought about. Ti has some of these, and others to boot, but not all of them. The same with carbon fiber, the same with ceramics.

 

We may invent some super material in the future ( and don't think that the materials science boys aren't diligently looking for that stuff) but for the last 2500 years steel is and has been the "super-unobtainium" that we are all looking for.

 

What I want is that carbon fiber sword with the mono-molecular spun diamond edge a micron thick bonded to it. Or a light saber, yah, that's the ticket.

 

:lol:;)

 

Geoff

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Titanium is actually a soft metal that is right around the same strength as mild steel. Its just a little shy in both yield and ultimate tensile strength compared to basic structural steel i.e. something like A36.

Alloys of titanium can achieve much higher spec 4-5 times that of mild steel. When comparing it to tool steels However you have to understand that being stronger does not equate to being more abrasion resistant. Martensitic steels have high abrasion resistance, But Titanium is a hexagonal Close pack Crystal and its method of hardening is by strain or strain induced by precipitation (as with the Ti Alloys) You can have a tough strong metal, but it is still relatively soft in terms of a abrasion resistance. So it dulls easily. You can make blades that behave like a nice spring steel, but they won't keep an edge nearly as well.

Other Draw back are the ten fold increase in cost of materials and the increased difficulty in working with the material. For something that does not hold an edge worth a damn, it is very difficult to grind, because of its tough gummy nature. So costs go up in every aspect of production, for no more gain than the marketing word "Titanium".

It does have its strengths. The impact strength and fatigue life on some of the alloys are incredible. Its almost ideal for Armour and Armor with the added benefit of 40 percent reduction in weight compared to steel.

Its corrosion resistance is awesome as well. The mechanism that makes that possible also makes Titanium nearly impossible to solder and it has to be welded in an inert environment.

Heattreatments are a PITA. 45min to 2 hours at temp to normalize or anneal it properly. Precipitation hardening of the alloy is also a PITA and most Blacksmiths are not set up to it properly.

 

Out of time the dishes are calling me...

Patrick :)

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I understand that it doesn't work well as a moving contact surface either, no matter if you call it a bearing surface or anything else. Read up on tribology a bit to learn more. On the plus side, however, the oxide layer on the Ti is electrically conductive and can be brushplated- a form of electroplating.

Brian

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  • 10 months later...

Like a volcano, if my experience is any clue. Just one safety warning, Ti is pretty toxic when breathed or in cuts and abrasions. A friend of mine inhaled a bunch several years ago and has never completely recovered.

 

Take care,

 

Geoff

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I recently fed my grinder some Titanium, Anyone curious as to how it sparks?

 

It makes a very white hot spark. And when you add that to oxidized steel dust cuttings from blades you get a mini thermite reaction. It's not an explosion it's a very hot fast burning fire. If there are not a lot of cuttings then it won't do much. I had a few of them and on a small scale it's interesting to watch but it could be a fire hazard if you had a lot of steel dust/cuttings. It's like several things in our craft that could go wrong.

 

And considering forum dynamics that doesn't mean that if you grind it the world will come to a cataclysmic end. I use titanium all the time, it's an amazing metal and an incredible challenge to work with.

 

If you grind it just keep the steel cuttings around your grinder to a minimum. If you do get a little reaction just disperse it with something that won't burn. It's a codependent reaction. It burns fast but if you separate it it goes out fast also.

 

I hope everyone plays with some and possibly uses it on some knives. It's almost as strong as steel and almost as light as aluminum. It doesn't corrode and can be anodized to many different colors.

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It makes a very white hot spark. And when you add that to oxidized steel dust cuttings from blades you get a mini thermite reaction. It's not an explosion it's a very hot fast burning fire. If there are not a lot of cuttings then it won't do much. I had a few of them and on a small scale it's interesting to watch but it could be a fire hazard if you had a lot of steel dust/cuttings. It's like several things in our craft that could go wrong.

 

And considering forum dynamics that doesn't mean that if you grind it the world will come to a cataclysmic end. I use titanium all the time, it's an amazing metal and an incredible challenge to work with.

 

If you grind it just keep the steel cuttings around your grinder to a minimum. If you do get a little reaction just disperse it with something that won't burn. It's a codependent reaction. It burns fast but if you separate it it goes out fast also.

 

I hope everyone plays with some and possibly uses it on some knives. It's almost as strong as steel and almost as light as aluminum. It doesn't corrode and can be anodized to many different colors.

 

Yea, I did a cold hammer test, it started to split, looks like its going to be very hot work for Ti.

I have a water bucket that lives under my grinder, and with the angle of my most common grinding, the metal bits just go right into the bucket, its a nice rust colored water, definitely tetinus prone. I empty it everytime it starts looking grody.

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