So I know Titanium is light and strong and all that, super, but except
for titanium carbie I've not heard anything about hardness or wear
resistance principles. I was thinking of getting a titanium crowbar and
that got me thinking, also I've heard of titanium bladed knives. So
anyway, my question is this, what is Titanium like on the Rockwell C
scale, any help would be appreciated and thanks in advance! :-)
For the very common Ti-6Al-4V alloy, expect about 30-36 HRC, depending
on microstructure. It is possible to get into the low 40's with work
hardened beta alloys like 38-6-4-4. Yet as the knowledgeable Michael
Dahms notes, the wear resistance is poor. The edge holding ability is
also poor, so I believe that titanium alloys are just wrong for knives.
Great corrosion resistance, of course, and it's sufficiently expensive
with an impressive reputation for strength to weight ratio so as to
make it marketable as exotic.
If you do make Ti alloy knives, look into coatings for the edge. I'd
recommend either a PVD coating like TiN or some varient of that type,
OR a nitriding process like Nobleizing, which we have done at Flowserve
Who makes those ? I've seen hammers, but not a crowbar. Could be useful
- you don't need much of an edge on it.
Only for saltwater diving, and they're not even very good at that.
Titanium knives are, by and large, a bit of a let down.
Depends on the alloy, and it's all going to be pretty low. 6/4 alloy is
the hardest you'll get - Google or Machinery's Handbook for the magic
The one time I've ever heard comment about Ti hardness (and that not
positive) is in bike frames. Frames are made of several alloys, cp
(pure), 3/2.5 (strongest alloy you can get seamless tubes in) and 6/4
(strongest, but the tubes have to be welded). The 6/4 frames are known
for having rear dropouts so stiff and with such surface hardness that
you can't get a nut and bolt to grip. Unless you use a fitting done up
with a tool, the typical hand-tightened bike wheel locating skewer is
prone to slipping out of the dropout if you hit a bump!
Those are only the alloys that are the most common.
"3/2.5 (strongest alloy you can get seamless tubes in)" Not true. I use
seamless Ti 6-4 in thin wall seamless at 1.5 " OD and 0.032" W.T
"6/4 alloy is the hardest you'll get." Not true. I know of alloys that
exceed 200ksi. Higher strength should be possible." I have a piece of Ti
15-3-3-3 seamless tubing 1"od x 0.028 wt that I use for a hiking staff. It
has a strength of 186ksi.
"stiff and with such surface hardness..." Not true. The stiffness of Ti is
roughly half way between steel and aluminum. You may be confusing stiffness
(Young's Modulus, a material property.) with moment of inertia, (a section
property.) Hardness is most commonly measured as a resistance to penetration
under standardized conditions. That means it varies with strength. The
loosening problem you reference can be from a wide variety of issues, not
just titanium. Airplanes use millions of titanium fasteners and have for
decades. We do not have problems with titanium bolts loosening.