What Is Grade 9 Titanium
Grade 9 titanium, UNS R56320, is an alpha-beta alloy containing aluminum 2.5 to 3.5 percent and vanadium 2.0 to 3.0 percent. It was developed as a compromise between the high strength of Ti-6Al-4V and the formability of commercially pure titanium. The result is an alloy with about two-thirds of the strength of Grade 5 that can be welded, bent and flared without the difficulties of higher-alloy material.
Composition and Properties
The alloy limits iron to 0.25 percent and oxygen to 0.15 percent maximum, which keeps the material ductile in thin sections. Minimum mechanical properties in wrought form are 620 MPa tensile strength, 483 MPa yield strength and 15 percent elongation. Density is 4.48 g per cubic centimetre, and the alloy is supplied annealed or cold-worked to the ordered strength level.
The Advantage over Grade 5
Ti-6Al-4V is difficult to weld in thin sections because the weld zone hardens and loses ductility. Grade 9 welds reliably with argon shielding and matching filler wire, and its formed tubes accept flaring and swaging without cracking. These characteristics make Grade 9 the practical choice for thin-wall tubing and formed parts where Grade 5 would be marginal.
Standards and Product Forms
Grade 9 is covered by ASTM B861 for pipe, ASTM B338 for heat exchanger tubing and ASTM B348 for bar, with AMS 4945 for aerospace hydraulic tubing. The alloy is available as tube, pipe, bar, wire and sheet. Aerospace supply adds the tighter dimensional and testing controls of the AMS specification.
Main Applications
Aircraft hydraulic and pneumatic tubing.
Bicycle frames and motorsport components.
High-pressure gas sampling lines.
Marine and offshore instrument tubing.
Chemical plant piping needing moderate alloy strength.
Fabrication Notes
Grade 9 is welded with argon shielding and cleaned surfaces, and thin-wall tube is formed with standard aerospace tooling. Bending, flaring and swaging are performed at room temperature with proper mandrels, and the finished part is cleaned and passivated. The alloy's good fatigue strength suits components that see vibration and pressure cycling.
Frequently Asked Questions
Q: What is Grade 9 titanium?
A: It is the alpha-beta alloy Ti-3Al-2.5V, UNS R56320, developed as a weldable, formable alternative to Ti-6Al-4V.
Q: How strong is Grade 9?
A: Minimum tensile strength of 620 MPa and yield strength of 483 MPa with 15 percent elongation.
Q: Why choose Grade 9 instead of Grade 5?
A: Grade 9 welds and forms far better in thin sections while keeping about two-thirds of the strength.
Q: Which specification covers aerospace tubing?
A: AMS 4945 covers seamless Ti-3Al-2.5V hydraulic tubing.
Q: What are the main applications?
A: Aircraft hydraulic lines, bicycle frames, gas sampling lines and marine instrument tubing.
Q: Is Grade 9 weldable?
A> Yes, it welds reliably with argon shielding and matching filler wire.
