Titanium C-23 Annealed
Temper
UNS R56407 · ASTM B367 Grade C-23
Use when only residual-stress relief and dimensional stability are needed and internal porosity is controlled by NDT acceptance.
Values for the Annealed condition
Other C-23 tempers and conditions
C-23 is listed in 5 conditions; see the grade overview at C-23.
- AS-CAST
- Annealed
- HIP+Annealed
- HIP
- STA
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
as-solidified, chem-milled, no HIP | Cheapest route for non-critical or low-stress castings where residual micro-porosity and lower fatigue life are acceptable. | 830 | 900 | 9 | 34 HRC | — |
AnnealedThis page vacuum annealed 730–845 °C, no HIP | Use when only residual-stress relief and dimensional stability are needed and internal porosity is controlled by NDT acceptance. | 840 | 910 | 11 | 33 HRC | — |
HIP + Anneal | Pick for maximum damage tolerance and dimensional stability in fracture-critical aerospace and implant castings. | 855 | 925 | 13 | 33 HRC | — |
HIPDefault Hot isostatic pressed | Standard supply condition for flight- and implant-critical castings: closes internal porosity and lifts fatigue and toughness toward wrought levels. | 860 | 930 | 12 | 34 HRC | — |
Solution treated and aged | Optional strengthening route (often after HIP) for thin-section castings needing higher yield strength, at the cost of toughness and ductility. | 920 | 1,010 | 8 | 36 HRC | — |
What is C-23 Annealed?
C-23 Annealed is C-23 in the Annealed temper — use when only residual-stress relief and dimensional stability are needed and internal porosity is controlled by NDT acceptance. C-23 Annealed has a yield strength of 840 MPa (122 ksi) and a tensile strength of 910 MPa (132 ksi) — stronger than 63% of titanium grades. Elongation at break is 11% and the elastic modulus is 112 GPa (16.2 Msi). C-23 Annealed has a density of 4.43 g/cm³ (0.16 lb/in³), lighter than 89% of titanium grades. It melts at 1,604°C (2,919 °F). HIP is the default condition FabDigit quotes; Annealed is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 80 MPa·√m (72.8 ksi·√in), better than 81% of titanium grades
- High service temperature — 400°C (752 °F), better than 78% of titanium grades
Limitations
- Poor heat conductor — 6.7 W/m·K (3.87 BTU/hr·ft·°F), worse than 92% of titanium grades
- Low electrical conductivity — 1 % IACS, worse than 89% of titanium grades
- Limited ductility — 11%, worse than 87% of titanium grades
- Limited formability — 20/100, worse than 83% of titanium grades
C-23 Annealed properties
Typical room-temperature values for C-23 Annealed; 10 are specific to this condition. Other listed values are C-23 reference data and may not represent this condition. Bars are the position among titanium grades.
Physical3
C-23 Annealed has a density of 4.43 g/cm³ (0.16 lb/in³), lighter than 89% of titanium grades. It melts at 1,604°C (2,919 °F).
Mechanical16
C-23 Annealed has a yield strength of 840 MPa (122 ksi) and a tensile strength of 910 MPa (132 ksi) — stronger than 63% of titanium grades. Elongation at break is 11% and the elastic modulus is 112 GPa (16.2 Msi).
Thermal6
C-23 Annealed is rated for continuous service to 400°C (752 °F). It conducts heat at 6.7 W/m·K (3.87 BTU/hr·ft·°F), worse than 92% of titanium grades. Thermal expansion is 8.8 µm/m·K (4.89 µin/in·°F).
Electrical3
C-23 Annealed conducts electricity at 1 % IACS, worse than 89% of titanium grades.
Chemical & Environmental3
Corrosion resistance is excellent (92/100), better than 53% of titanium grades.
Sustainability4
Producing a kilogram of C-23 Annealed takes about 700 MJ of energy and emits 45 kg of CO₂ — more than 74% of titanium grades. Typical recycled content is 25%.
Manufacturability8
C-23 Annealed's machinability is poor (20/100, worse than 68% of titanium grades); weldability very good (75/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C-23 Annealed
Is C-23 easy to machine?
Machine with sharp uncoated/fine-grain carbide, low surface speed (25–50 m/min), heavy positive feed and flood coolant; remove the α-case (0.1–0.5 mm) by chem-mill or grinding before finish cuts, and avoid dwell to prevent work hardening and fire risk with fine chips.
Can C-23 be welded?
GTAW/EBW/laser welds readily in vacuum or fully inert-shielded chambers with matching ELI filler; keep interstitials, moisture and grease out, back-purge, and stress relieve after weld repair per AWS D17.1.
Can C-23 be formed, bent or molded?
Vacuum-melted (VAR/skull) and poured into rammed graphite or ceramic investment molds; allow ~1.5–2 % shrink, expect coarse prior-β grain, and specify HIP to close shrinkage porosity.
What surface finishes work on C-23?
Chem-mill or grit blast + pickle to strip α-case, then anodize per AMS 2488, passivate for implant use (ASTM F86), or plasma-spray HA; avoid chlorinated cleaners and cadmium/mercury contact.
C-23 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Al | 5.5 – 6.75 | 6 |
| V | 3.5 – 4.5 | 4 |
| FeELI limit | ≤ 0.25 | 0.15 |
| Oextra-low interstitial oxygen | ≤ 0.13 | 0.1 |
| C | ≤ 0.08 | 0.03 |
| N | ≤ 0.05 | 0.02 |
| Hcastings, vacuum annealed | ≤ 0.02 | 0.01 |
| Yyttrium limit for cast product | ≤ 0.01 | — |
| Other, eachresidual elements | ≤ 0.1 | — |
| Other, totalresidual elements | ≤ 0.4 | — |
| Ti | balance | — |
C-23 Annealed — frequently asked
What is C-23 Annealed used for?
C-23 Annealed is typically used for aerospace structural castings, surgical implant housings, cryogenic fittings and fracture-critical brackets. In short: highest-toughness cast Ti-6Al-4V; ELI implant-grade castings; fracture-critical aerospace parts.
What is the yield strength of C-23 Annealed?
C-23 Annealed has a typical yield strength of 840 MPa (122 ksi) and a tensile strength of 910 MPa (132 ksi) — stronger than 63% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is C-23 Annealed easy to machine?
Not especially — machinability is rated poor (20/100, worse than 68% of titanium grades). Machine with sharp uncoated/fine-grain carbide, low surface speed (25–50 m/min), heavy positive feed and flood coolant; remove the α-case (0.1–0.5 mm) by chem-mill or grinding before finish cuts, and avoid dwell to prevent work hardening and fire risk with fine chips.
Can C-23 Annealed be welded?
Yes — weldability is rated very good (75/100). GTAW/EBW/laser welds readily in vacuum or fully inert-shielded chambers with matching ELI filler; keep interstitials, moisture and grease out, back-purge, and stress relieve after weld repair per AWS D17.1.
What surface finishes work on C-23 Annealed?
Chem-mill or grit blast + pickle to strip α-case, then anodize per AMS 2488, passivate for implant use (ASTM F86), or plasma-spray HA; avoid chlorinated cleaners and cadmium/mercury contact.
Can C-23 Annealed be formed, bent or molded?
Vacuum-melted (VAR/skull) and poured into rammed graphite or ceramic investment molds; allow ~1.5–2 % shrink, expect coarse prior-β grain, and specify HIP to close shrinkage porosity.
What is the maximum service temperature of C-23 Annealed?
C-23 Annealed is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C-23-HIP and C-23-STA?
HIP is the default condition — standard supply condition for flight- and implant-critical castings: closes internal porosity and lifts fatigue and toughness toward wrought levels. STA: optional strengthening route (often after HIP) for thin-section castings needing higher yield strength, at the cost of toughness and ductility. Yield strength is 860 MPa in HIP versus 920 MPa in STA.
Sources
- ASTM B367 Standard Specification for Titanium and Titanium Alloy Castings — ASTM International (2022)
- ASTM F1108 Ti-6Al-4V Alloy Castings for Surgical Implants — ASTM International (2021)
- ASTM F136 Wrought Ti-6Al-4V ELI for Surgical Implants — ASTM International (2022)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 19 — Fatigue and Fracture — ASM International (1996)
- Materials Properties Handbook: Titanium Alloys — ASM International (1994)
- MMPDS Ti-6Al-4V design allowables (reference data) — Battelle/FAA (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.