Everything You Wanted To Know About Titanium
If steel and titanium are both equal in strength, then aluminum is half the strength. When you get into the 7000 series of aluminum they get to about two thirds the strength of titanium. The problem is that the ductility of aluminum is less than steel. This is what comes into play when designing parts, especially the axles and some bolts, like cylinder head bolts, the stretchiness becomes an issue with titanium. And the technical term for that is modulus of elasticity. That's why a when looking at a titanium spring, it has less coils in it. With the modulus number of titanium being half of steel it's going to flex twice as much for the same amount of load.
So let's give an example. Let's say it's a steel bolt and you give it 1,000 pounds of force on the bolt, the bolt is going to stretch a certain amount. A titanium bolt with that same 1000 pounds of force is going to stretch twice as much. Because of stretching it will still carry the load as long as you are within the elastic limit. That's why people say they have a problem with the bolt stretching, but they both stretch until they come up to the clamp load that holds the assembly together. In motorcycle terms we see this in the triple clamps. There have only been a few riders we know that have the ability to tell the difference between steel bolts and titanium bolts. That same rider can tell the difference between 15 foot-pounds and 18 foot-pounds of torque. There are only a few riders that are that sensitive to tell the tiny differences in the triple clamps. Across the board right now we pretty much have everybody running titanium triple clamp bolts and titanium front axle pinch bolts.
The precursor to it, everyone talks about the factory teams having the advantages. Back in the ‘60s and ‘70s, with the titanium coming out of the aerospace industry, a lot of the factory teams had access and the budget to be able to build titanium fasteners. Back in the ‘70s, going into the early eighties, the machining of titanium was quite tricky. The CNC machines and the quality of the cutting tools to cut the material were still relatively expensive and hard to handle. If you talk to anyone that has been around motocross for a long time like Roger DeCoster, back in the ‘70s he had bikes totally decked out with titanium fasteners with the factory programs. But for privateers it was really hard to get their hands on it. Then CNC machines were more available, but this is where a lot of the bad wrap started with titanium axles and fasteners. CNC machines were coming along and people could take titanium bar and machine it and make a fastener by just purely machining it out of bar stock. The problem with that is if you want to make an aircraft quality fastener, it needs to be hot forged, meaning it needs a forged head to get the proper grain structure, followed by the proper heat treating and then you need to have a rolled thread.
When it comes time for assembly, we recommend to use anti-seize of some type. It can be an aluminum or copper anti-seize, but better than that, we like to use moly assembly paste. So the same moly paste that you'd put on your cam lobes. Look for one with a 40 percent moly content. The molybdenum gets ground into the surface and prevents any galling between the titanium and aluminum, or ti on titanium nut. With axles, a thin layer of grease is recommended so the bearing isn't beating on the dry axle. Then, when you're doing your normal maintenance pull them out and drop them in 409 or Simple Green to soak them overnight or if you have an ultrasonic cleaner they'll come out super bright and clean again. In some places you need to use Loctite like on rear sprockets, you can use blue Loctite on it and it actually also keeps the bolts from galling.
Titanium screw(Most of titanium alloy screws are titanium Gr.5, Ti-6al4v) have high specific strength, tensile strength up to 100-140kgf/mm2, and density is only 60% of steel.
Anode materials develop and become various under a variety of anode working conditions. MMO titanium anode that using titanium as substrate and high catalytic activity of platinum group metal oxide as the coating with good electrical conductivity, small output resistance and good formability without corrosion applied widely in seawater, fresh water and soil environments. The protected metal connecting metal with smaller negative potential to form anode and the protected metal in the electrolyte solution to form a big source, this is called sacrificial anode protection, current flows through anode, electrolyte solution and then goes to the metal equipment to make metal equipment cathodic polarization protection.
Not only is standard-size grade 2 titanium pipe and tube available from inventory or quick production runs, larger sizes also can be produced by independent fabricators. Many of them also can design and produce complete piping systems, heat exchangers, and pressure vessels. This geographically diverse fabrication base has more than 25 years of engineering and design experience.
When considering the design of a stud or Gr5 titanium bolt used for cyclically loaded fastener, it is important to consider both the fastener stiffness and the stiffness of the parts being clamped. A simple formula involving these quantities dictates how the service load is shared between the unloading of the joint, and the extra load borne by the fastener. This relationship has been covered in one of the early RET Monitor articles on fasteners and in a past article in Race Engine Technology magazine*.
About titanium bolts
Bicycle titanium bolt come closest to steel in terms of strength but Ti is 47% lighter.
Note, although Ti bolts can be as strong as mild steel bolts,they are no substitute for high tensile steel bolts. Syntace sell some high quality Ti bolts and here is what they say about high-tensile bolt replacement.
Why titanium’s the best option
There are a few materials approved by the Association of Professional Piercers (APP), but implant-grade titanium is the one most piercers recommend for initial piercings.
It’s nickel-free. Nickel is the most common contact allergen in the world, according to the European Centre for Allergy Research Foundation. It’s regularly found in jewelry for piercings. Titanium doesn’t contain any nickel, which makes it safe for people with sensitive skin or a nickel allergy.
It has a high strength-to-density ratio. In other words, titanium is considerably less dense than stainless steel and other metals, but just as strong (if not more so). This makes it durable and less likely to bend or break.
It’s lightweight. That low density we just talked about is what makes titanium studs lighter than those made with other metals.