Alloy Identity and Standard Basis
TB10 is a metastable beta titanium alloy in the GB designation system, covered by GB/T 3620.1, with a composition based on molybdenum, vanadium, chromium and aluminium additions that stabilise the beta phase and allow a high strength to be developed by solution treatment followed by aging. It is supplied as bar, wire and forging stock to GB/T 2965 and is used for high strength structural components, fasteners and airframe hardware where a combination of strength above 1000 MPa, low density and good corrosion resistance is required.
The alloy is prepared for two reasons. First, metastable beta alloys respond to heat treatment, so the same chemistry can be supplied in a soft condition for forming and then strengthened at the point of use. Second, the beta structure has good through-hardening behaviour, so large sections can be strengthened uniformly rather than only at the surface.
Melting and Ingot Preparation
Production starts with selection of raw materials and careful charge preparation, because the purity and ratio of the input materials govern everything downstream. Sponge titanium of controlled grade is blended with master alloys of the beta stabilisers and with aluminium, then compacted into electrodes. Melting is carried out in a vacuum consumable arc furnace, usually with two or three successive melts to improve chemical homogeneity. The vacuum environment removes volatile impurities and dissolved gases, and repeated melting reduces segregation of the heavier alloying elements, which is the main risk in a beta rich composition.
After melting the ingot is conditioned by machining or grinding to remove surface defects and the oxygen enriched layer, and the chemistry is verified at top, middle and bottom to confirm that no macro-segregation remains.
Forging and Thermomechanical Processing
Forging improves the cast microstructure and converts it into a worked structure with better mechanical properties. The route for TB10 normally includes open die forging, three direction upsetting and drawing, and two direction upsetting and drawing, with intermediate reheating. Temperature and reduction ratio are controlled closely during each pass for two reasons: overheating above the beta transus produces coarse beta grains that cannot be refined later, and burning at the surface creates brittle cracks that propagate during subsequent working.
| Process stage | Control point | Purpose |
|---|---|---|
| Open die forging | Temperature below beta transus, moderate reduction | Break up the cast structure |
| Multi-directional upsetting and drawing | Alternating strain direction, controlled reheat | Refine and homogenise grain structure |
| Final forging | Finish temperature and reduction ratio recorded | Set the structure for heat treatment response |
| Post forge cooling | Controlled cooling rate | Avoid residual stress and cracking |
Solution Treatment and Aging
After forging the material is solution treated and aged. Solution treatment is carried out at high temperature, above the beta transus or in the upper alpha-beta field depending on the property balance required, and followed by rapid cooling so that the alloying elements stay in solution and a metastable beta structure is retained. Aging is then performed at a lower temperature, typically in the 480 to 560 °C range, to precipitate fine secondary phase particles throughout the matrix. The precipitates are what raise the strength: without aging the alloy stays soft and formable, and after aging it reaches strength levels in the 1100 MPa class or above.
Both temperature and time must be recorded for each batch, because aging at too low a temperature leaves the alloy under-aged and below the property target, while over-aging coarsens the precipitates and lowers strength while increasing ductility. Cooling rate from solution treatment is equally important: slow cooling allows precipitation to begin prematurely and reduces the response to the subsequent aging treatment.
Machining, Inspection and Delivery
Titanium alloys machine poorly because of low thermal conductivity and a strong tendency to gall the cutting edge. TB10 is normally machined with coated carbide or hard wearing tooling, sharp edges, low cutting speed, generous feed and flood coolant, with rigid setups to suppress chatter. Grinding is used for finishing where dimensional control is critical, and a stress relief treatment may be applied to machined parts before final aging.
Delivery inspection for TB10 bar and forgings covers chemical composition, tensile properties in the specified heat treatment condition, hardness, microstructure evaluation of the beta grain size and the forged structure, and ultrasonic inspection for internal defects. Records are supplied as a mill test certificate to EN 10204 3.1 with the heat number traceable through melting, forging and heat treatment, so the customer can confirm that the properties were developed by the route recorded on the certificate rather than by re-testing a different lot.
Frequently Asked Questions
Q: What kind of alloy is TB10?
A: It is a metastable beta titanium alloy designated under GB/T 3620.1, developed for high strength structural and fastener applications and strengthened by solution treatment and aging.
Q: Why is vacuum arc melting used for titanium alloys?
A: The vacuum environment removes dissolved gases and volatile impurities, and multiple melting passes reduce segregation of heavy alloying elements, giving a chemically homogeneous ingot.
Q: Why does forging temperature matter so much?
A: Working above the beta transus creates coarse beta grains that cannot be refined afterwards, while overheating locally can burn the surface and initiate cracks during subsequent passes.
Q: What does aging do to TB10?
A: It precipitates fine secondary phase particles within the metastable beta matrix, raising strength to the 1100 MPa class while retaining usable ductility and toughness.
Q: How is TB10 bar inspected before delivery?
A: Chemical analysis, tensile testing in the specified condition, hardness and microstructure evaluation, dimensional checks and ultrasonic inspection for internal defects, reported on a certificate to EN 10204 3.1.
