Solution Treat + Age (Ti)
Solution treat & age · Precipitation hardening
Solution Treat + Age (Ti) is a precipitation-hardening condition for Ti-6Al-4V and Ti-6Al-6V-2Sn and Ti-10V-2Fe-3Al.
Ti STA at a glance
Four scores, each 0–100 against every heat treatment in this catalog. Hardness is derived from the HRC target (20 HRC = 0, 70 HRC = 100) — treatments without a hardness target (anneals, stress relief, HIP, cryo) are not rated. Toughness, dimensional stability and cost are FabDigit's engineering assessment.
What is Ti STA?
Solution Treat + Age (Ti) is a precipitation-hardening condition for Ti-6Al-4V and Ti-6Al-6V-2Sn and Ti-10V-2Fe-3Al. It develops strength by solution treatment followed by controlled aging; the final condition, material specification, and acceptance test belong on the drawing.
How it works
Solution treatment dissolves strengthening constituents and establishes a controlled starting microstructure. Cooling retains a supersaturated or otherwise metastable matrix. During the prescribed age, diffusion forms a fine dispersion of strengthening precipitates that obstruct dislocation motion. Temperature and time control precipitate size, spacing, coherency, and grain-boundary chemistry: lower or shorter cycles generally favor peak strength, while overaging trades some strength for toughness, conductivity, or stress-corrosion resistance. The complete route, including the incoming material condition and cooling practice, is therefore part of the engineering definition.
Why specify it
- Produces 36–44 HRC across the stated grade set
- Provides 1100 MPa or greater tensile capability where the cited product condition defines it
- Adds strength through precipitation rather than a carbon-steel temper
- Can be applied after near-net machining with less movement than a severe steel quench
Where it falls short
- Properties depend on alloy, product form, section size, and incoming condition
- Overaging or underaging can miss both strength and corrosion targets
- Solution treatment or quenching may distort thin and asymmetric parts
- A condition name does not replace material heat-lot traceability
The Ti STA cycle
Typical furnace parameters from the governing specifications and shop practice; the heat treater sets the exact recipe from the alloy, section size and required result.
| Temperature | 900–970 °C (1,652–1,778 °F) — Primary solution or age temperature window represented by the stages; use the alloy-specific specification. |
|---|---|
| Soak | 0.5–2 h — At-temperature time; load and section corrections may apply. |
| Cooling | Water quench |
| Atmosphere | Vacuum / argon |
| Door to door | 8–16 h — Typical furnace cycle excluding queue and laboratory testing. |
Stages
- 1Solution treat below or above beta transus as required by alloy and property target
- 2Quench using the approved medium and transfer time
- 3Age typically 480–595 °C for 4–8 h, then air cool
What Ti STA does to the part
| Hardness | 36–44 HRC (340–410 HB) — Condition and product-form range; Brinell is commonly reported as 340–410 HB. |
|---|---|
| Section affected | The whole section transforms. |
| Tensile strength | 1,100–1,275 MPa — Ti-6Al-4V STA is commonly specified at 1,100 MPa minimum tensile strength; exact requirements depend on product form. |
| Toughness | Strength rises above annealed Ti-6Al-4V, while ductility and fracture toughness decrease and depend strongly on solution temperature. |
| Distortion | Medium risk. Rapid quenching can move thin asymmetric sections; aging is low distortion. |
| Surface after treatment | Vacuum or inert processing limits alpha case; air exposure can create brittle oxygen-enriched scale. |
| Machining sequence | Machine before STA where possible; remove alpha case and finish critical fatigue surfaces afterward. |
Specifications for Ti STA
The documents a drawing cites to define this treatment. Each links to a page explaining the standard, its classes and the tests it invokes.
| Standard | Role | Classes used | Status |
|---|---|---|---|
Heat Treatment of Titanium Alloy Parts | Governing | — | Active |
Test and related methods: ASTM E18 (Standard Test Methods for Rockwell Hardness of Metallic Materials), ASTM F3055 (Standard Specification for Additive Manufacturing Nickel Alloy (UNS N07718) with Powder Bed Fusion), ASTM F3301 (Standard for Additive Manufacturing—Post Processing Methods—Standard Specification for Thermal Post-Processing Metal Parts Made Via Powder Bed Fusion).
Drawing call-out
TI-6AL-4V SOLUTION TREAT AND AGE PER AMS 2801; UTS 1100 MPa MIN; HARDNESS 36–44 HRC PER ASTM E18; NO VISIBLE ALPHA CASEWhich alloys take Ti STA?
Verdict per material family, with the grades that behave differently. Each family links to its datasheets in the material library. Typical grades: Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-10V-2Fe-3Al.
| Material family | Verdict | Notes |
|---|---|---|
| Yes | Applicable to alpha-beta and selected beta titanium alloys with an approved STA schedule.
| |
| With care | Common for qualified Ti-6Al-4V AM parts after stress relief or HIP.
| |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. | |
| No | This alloy category does not use the titanium STA cycle. |
Design rules for Ti STA
What to decide on the drawing before the part goes to the heat treater.
- Remove alpha case produced by air exposure where fatigue surfaces require it.The precipitation response depends on the material condition entering the age cycle.
- Use vacuum or inert gas and clean fixtures to prevent oxygen pickup.Uniform temperature and controlled transfer reduce property variation and distortion.
- State the alloy, product specification, final condition, and hardness-test method on the drawing.A condition name alone does not define material pedigree or acceptance sampling.
- Protect finished dimensions and verify critical fits after treatment.Precipitation aging is low-distortion but can still produce measurable contraction or growth.
Ti STA versus the alternatives
Treatments engineers weigh against Ti STA, and when each wins.
| Treatment | Hardness | Toughness | Stability | Cost | Choose it when |
|---|---|---|---|---|---|
Ti STA this page | 40 | 58 | 60 | $$$$ | — |
| — | 90 | 55 | $$$ | when ductility and fracture toughness are more important than peak strength | |
| — | 75 | 65 | $$$$ | when AM internal porosity must be reduced before final heat treatment |
Cost, lead time and applications
Relative cost
Solution Treat + Age (Ti) is a high-cost treatment ($$$$) relative to the other heat treatments in this catalog.
Heat treatment is priced per lot with a furnace minimum. The exact figure appears on the instant quote once the part is uploaded.
Lead time
| Added lead time | 3–10 working days |
|---|---|
| Furnace time | 8–16 h |
What Ti STA is used for
- Aerospace structural hardware
- Precision shafts, fittings, and actuators
- High-strength tooling and fixtures
- Corrosion-resistant mechanical components
Ti STA — frequently asked
What does Ti STA mean?
Ti STA identifies a controlled solution-treatment and precipitation-aging condition, not a generic furnace temper. The drawing should also identify the alloy specification and acceptance hardness or tensile requirement.
Is this a quench-and-temper treatment?
No in the metallurgical sense. Strength comes primarily from fine precipitates formed during aging rather than tempering quenched carbon-steel martensite.
Will the part distort?
The expected risk is medium. Aging is normally more stable than a hard steel quench, but residual stress, section changes, fixtures, and prior solution treatment still matter.
How should hardness be verified?
Use ASTM E18 for Rockwell hardness on a suitable flat section. The expected catalog range is 36–44 HRC; thin sections may require ASTM E384 microindentation and an approved conversion.
Can the condition be assigned after machining?
Usually yes when the starting material and process route are compatible. The purchase order must preserve traceability to the governing product specification and the heat treater must certify the complete cycle.