Originally Posted by
sweeks
I don't know what grade bolts you are using but from my experience, titanium bolts used for bicycle parts are extremely easy to round out. I've had a number of bolts on seatpost clamps and stems from reputable manufacturers rounded out very easily...much more easily than equivalent steel and stainless fasteners. I've also been told by a machinist friend that titanium is soft but work hardens easily.
As to hardness, the Mohs scale is probably not the best scale to use. Bondhus allen wrenches have a Rockwell C hardness of about 80. Grade 5 (6AL-4V) titanium has a Rockwell C hardness of 36. The other grades range from Rockwell C 98 (Grade 2) to 23 (Grade 4). Most of the grades are softer than the Bondhus tool. Stainless steel bolts, which are what I typically use, have a Rockwell hardness of about 70. They are tougher in my experience.
Perhaps the manufacturers should be using a higher grade titanium fastener but my experience tells me to go easy on titanium bolts as they are easy to ruin.