Titanium C-23
UNS R56407 · ASTM B367 Grade C-23
C-23 is extra-low-interstitial cast Ti-6Al-4V to ASTM B367 (Grade C-23, UNS R56407), offering improved fracture toughness and fatigue performance over standard C-5.
Reference datasheet — C-23 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the HIP condition
C-23 tempers and conditions
C-23 is supplied in 5 conditions, soft to hard. HIP is the default FabDigit quotes; the values on this page are for it.
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 | — |
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?
C-23 is extra-low-interstitial cast Ti-6Al-4V to ASTM B367 (Grade C-23, UNS R56407), offering improved fracture toughness and fatigue performance over standard C-5. It is specified for fracture-critical aerospace and biomedical castings at 860 MPa yield, 930 MPa tensile, 12 % elongation and 330 HB / 34 HRC, with service to about 400 °C, in as-cast, annealed, HIP, HIP + annealed or STA condition. Machinability is poor (score 20), alpha case of 0.1–0.5 mm must be removed, and vacuum melting plus HIP makes it costlier than C-5, which remains the choice for non-critical castings. C-23 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). C-23 has a yield strength of 860 MPa (125 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 71% of titanium grades. Elongation at break is 12% and the elastic modulus is 112 GPa (16.2 Msi).
What is C-23 used for?
- aerospace structural castings
- surgical implant housings
- cryogenic fittings
- fracture-critical brackets
Advantages
- Tough — resists crack growth — 85 MPa·√m (77.4 ksi·√in), better than 91% 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 formability — 20/100, worse than 83% of titanium grades
- Limited ductility — 12%, worse than 78% of titanium grades
C-23 properties
Typical room-temperature values for C-23-HIP; bars are the position among titanium grades.
Physical3
C-23 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 has a yield strength of 860 MPa (125 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 71% of titanium grades. Elongation at break is 12% and the elastic modulus is 112 GPa (16.2 Msi).
Thermal6
C-23 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 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 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's machinability is poor (20/100, worse than 68% of titanium grades); weldability very good (75/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the titanium family
Yield strength against density for every titanium grade FabDigit runs. C-23 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C-23
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.
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 |
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.
Surface treatments FabDigit runs on titanium parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Titanium C-23 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R56407
- ASTM
- B367 Grade C-23
- Also called
- Ti-6Al-4V ELI Casting
How much does C-23 cost?
C-23 is a high-cost titanium ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C-23 — frequently asked
What is C-23 used for?
C-23 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?
C-23 has a typical yield strength of 860 MPa (125 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 71% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is C-23 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 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?
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 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?
C-23 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.
How much does C-23 cost?
C-23 is a high-cost titanium ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.