Thanks for the intel--very good to know. Naturally there's only so much that gets communicated to me as an external designer rather than being involved in direct communication with the manufacturer, and little details like that are helpful when it comes to making optimization tweaks and adjustments!
For our viewing audience here, one thing I want to stress (no pun intended) is the work-hardening effect for something like this hatchet. Work-hardening doesn't even capture it, so I used to call it "seasoning." Ti alloys, especially alpha-beta alloys, are sado-masochistic and love to get slapped around impacted. The more it gets used, the better it will get. This effect isn't subtle, you will notice it by the third sharpening when it seems like it never needs a fourth. It will "awaken" as it's used, and literally get stronger.
My heat treatment techniques reduce this effect by a lot, by drastically changing the crystalline matrix, but it really only works on a Beta or near-Beta alloy, by converting a large part of the matrix from Beta into Alpha Prime, or even Alpha Double Prime, which is also called "titanium martensite." This is a very internally-stressed form.
This isn't a thing in titanium industrial use. Normally the properties of each alloy are altered through alloying alone, with or without the intent of solution treating and aging, which is to increase strength, refine grain, reduce stress, equalize, etc, not to harden. Whatever Rockwell hardness results is simply a side effect and has little to no bearing on expected mechanical properties. In fact an HRC test on titanium can be like 5 points above or below the average number on a single sample, and is not considered a useful metric in titanium engineering.
The hatchet's performance will not be determined by a Rockwell test number, but that number will go up with use. For blades there is still a correlation.
Edit to add, for use as a blade titanium will naturally be "harder," but it isn't like a 'What Rockwell you run that at?' kind of thing. I just use the term "harden" because that's the word typically used to describe the effect. Alpha Prime is significantly harder than an Alpha-Beta matrix as a matter of course, but the hardness number isn't the goal. The goal is to put the titanium into a form where is can NOT gall, take a set, smoosh, roll, etc. If it is impacted beyond its yield strength, it will instead chip or break a little piece off of the edge, but this takes something crazy like swinging and hitting a rock. Even in this form, it isn't very abrasion-resistant but is incredibly stable and strong, even for a fine thin edge, and is flexible but quite stiff.
