MachIVshooter
Member
It's not that tough to work with if you know what you're doing and have appropriate tooling. Deep drilling and tapping is always a bit of a chore if you don't have high pressure coolant, though.
The strength & durability of Ti is subjective. Ti alloys can be the strongest out there proportionate to weight, but it can never match high carbon steel alloys and high strength martensitic stainless alloys for shear or yield strength. It also doesn't do well with friction; it will gall badly. Ti barrels have been tried and the rifling stripped out of them in short order.
I wouldn't call a metal that won't fatigue substantially until >900°F "extremely heat sensitive". Ti has a higher melting point than steel alloys. The issue is that it can oxidize at temperatures over 1,000°F. That's not necessarily a problem, though, and Ti is used in high performance IC engine valves, which easily exceed that temperature. And no, Ti doesn't harden from heating alone. It does work harden, though, if you don't keep your feed up or if you try to take cuts too light or with a cutter that isn't sharp enough.
The upside to Ti, particularly 6/4, is that it is very strong in the annealed state, 130,000 PSI yeild strength. It doesn't gain all that much from tempering, nothing like 7000 series aluminums or carbon steels. Full hard temper 6/4 will have a TYS of 160,000-165,000 PSI and won't be appreciably harder than annealed material. I find annealed 6/4 and full temper AMS 4965 behave about the same in terms of machining.
Ti is definitely suitable for some firearm parts, and it will absolutely save you weight. But it's not acceptable for barrels, hammers, sears, bolts in semi-auto firearms or other high friction applications. I've built one firearm with a fully titanium receiver & barrel block, and used the material for many other parts in other builds, including the bolt & barrel extension in my ultralight pack rifle.
The barrel latch, mag catch and safety selector of my 9mm folding pack rifle are also 6/4 Ti. 7075-T651 receiver
And, of course, I use the snot out of it for suppressors. Nearly all of mine have 3/2.5 tubes, and I have made whole monocores out of 6/4, as well as taper mount and integral brakes
That said, unless you want the exclusivity of it and have a lot of experience working with the metal, I wouldn't go Ti for a 1911 frame. There are some pretty tricky cuts that are further complicated by the material, and you're talking a $200+ piece of stock even if you buy a drop.
If I were going to blue it, I'd use 4140/4142 or 4340 in the pre-hardened condition. If I wanted stainless, I'd opt for 17-4 H1150 and then heat treat it to H900. If light weight were the goal, anodized 7075-T6 frame and carbon or stainless steel slide.
416 stainless would also be a good option if you want easy machining, but it would need to be heat treated, and does distort a bit, so you'd need to leave enough meat for final fitting & finishing post-temper. Same thing if you use annealed chromoly and harden it later (you don't want to do that, annealed CRMO machines like crap)
You can also use 4000 series CRMO for fire control parts, stuff can be tempered to pretty high hardness with good strength. Many tool steels or knife steels are also suitable, but a bit more critical on the temper to avoid temper embrittlement. Stainless can be used, but will not harden like CRMO or especially tool steels, so it's not my first choice. I've used lots of 4140, A-2, D-2, S-7 and 0-1 for fire control parts. I've also made a fair amount of small parts by cutting up chisels, punches and other tools that were already hardened.
On barrel, I'd recommend just buying one. Rifling is no easy task, and you'll spend more on the chamber reamer than you would a halfway decent finished barrel.
