Titanium Grade C-6-ELI
Grade
ASTM B367 Grade C-6
ELI = extra-low-interstitial casting variant (O ≤ 0.12 %), HIP + annealed
Specified for liquid-hydrogen/oxygen and other cryogenic hardware where toughness down to −253 °C matters more than room-temperature strength.
Values for the ELI condition
Other Grade C-6 tempers and conditions
Grade C-6 is listed in 5 conditions; see the grade overview at Grade C-6.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ELIThis page Extra-low-interstitial casting variant (O ≤ 0.12 %), HIP + annealed | Specified for liquid-hydrogen/oxygen and other cryogenic hardware where toughness down to −253 °C matters more than room-temperature strength. | 720 | 790 | 14 | 27 HRC | 1.1 % IACS |
As fabricated | Baseline condition for non-critical castings where porosity from solidification is acceptable. | 790 | 850 | 8 | 31 HRC | — |
Annealed | Pick when residual casting/welding stresses must be removed and ductility made uniform. | 795 | 855 | 10 | 30 HRC | 1.1 % IACS |
HIP+ANNDefault HIP + Annealed | Standard aerospace/cryogenic casting delivery condition: densified, stress-free and dimensionally stable. | 800 | 860 | 12 | 31 HRC | — |
Hot isostatic pressed | Choose for fatigue- or fracture-critical castings; HIP closes internal shrinkage porosity. | 805 | 870 | 12 | 31 HRC | 1.1 % IACS |
What is Grade C-6-ELI?
Grade C-6-ELI is Grade C-6 in the ELI grade — specified for liquid-hydrogen/oxygen and other cryogenic hardware where toughness down to −253 °C matters more than room-temperature strength. Grade C-6-ELI has a yield strength of 720 MPa (104 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 53% of titanium grades. Elongation at break is 14% and the elastic modulus is 107 GPa (15.5 Msi). Grade C-6-ELI has a density of 4.48 g/cm³ (0.162 lb/in³), lighter than 71% of titanium grades. It melts at 1,540°C (2,804 °F). HIP+ANN is the default condition FabDigit quotes; ELI is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 90 MPa·√m (81.9 ksi·√in), better than 97% of titanium grades
- High service temperature — 480°C (896 °F), better than 90% of titanium grades
Limitations
- Hard to polish — 60/100, worse than 97% of titanium grades
- Limited formability — 20/100, worse than 83% of titanium grades
Grade C-6-ELI properties
Typical room-temperature values for Grade C-6-ELI; 23 are specific to this condition. Other listed values are Grade C-6 reference data and may not represent this condition. Bars are the position among titanium grades.
Physical3
Grade C-6-ELI has a density of 4.48 g/cm³ (0.162 lb/in³), lighter than 71% of titanium grades. It melts at 1,540°C (2,804 °F).
Mechanical16
Grade C-6-ELI has a yield strength of 720 MPa (104 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 53% of titanium grades. Elongation at break is 14% and the elastic modulus is 107 GPa (15.5 Msi).
Thermal6
Grade C-6-ELI is rated for continuous service to 480°C (896 °F). It conducts heat at 8 W/m·K (4.62 BTU/hr·ft·°F), better than 51% of titanium grades. Thermal expansion is 9.4 µm/m·K (5.22 µin/in·°F).
Electrical3
Grade C-6-ELI conducts electricity at 1.1 % IACS, worse than 67% of titanium grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), worse than 77% of titanium grades.
Sustainability4
Producing a kilogram of Grade C-6-ELI takes about 680 MJ of energy and emits 45 kg of CO₂ — more than 51% of titanium grades. Typical recycled content is 25%.
Manufacturability8
Grade C-6-ELI's machinability is poor (25/100, better than 53% of titanium grades); weldability excellent (85/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Grade C-6-ELI
Is Grade C-6 easy to machine?
Machine like other alpha titanium: rigid setup, sharp uncoated-carbide or PVD tools, 25–45 m/min, heavy flood coolant, positive rake and no dwell — alpha case from casting must be removed by chem-mill/grinding before finish cuts.
Can Grade C-6 be welded?
Readily GTAW/EBW/laser welded with matching filler under full argon or vacuum trailing/backing shielding; keep O+N pickup low, weld colour must be bright silver, and post-weld stress relieve 540–650 °C.
Can Grade C-6 be formed, bent or molded?
Supplied as investment or rammed-graphite castings from vacuum-arc skull or induction melting; allow generous shrink (~1.5 %), HIP to close shrinkage porosity — cold forming of the casting is not practical.
What surface finishes work on Grade C-6?
Chemical mill or grit blast plus pickle to remove shell and alpha case, then anodise (Type II colour / AMS 2488 Type III), chemical convert or dry-film lubricate; avoid chloride-bearing marking inks before elevated-temperature service.
Grade C-6 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 |
|---|---|---|
| Alalpha stabiliser | 4 – 6 | 5 |
| Sn | 2 – 3 | 2.5 |
| Fe | ≤ 0.5 | 0.25 |
| OELI variant ≤ 0.12 % | ≤ 0.2 | 0.15 |
| C | ≤ 0.1 | 0.03 |
| N | ≤ 0.05 | 0.02 |
| H0.0150 % max on castings | ≤ 0.02 | 0.01 |
| Residuals (each)total 0.40 max | ≤ 0.1 | — |
| Ti | balance | — |
Grade C-6-ELI — frequently asked
What is Grade C-6-ELI used for?
Grade C-6-ELI is typically used for cryogenic tankage fittings, aerospace ducting castings and pressure vessel components. In short: alpha alloy, weldable; cryogenic to 480 °C; alternative to cast C-5.
What is the yield strength of Grade C-6-ELI?
Grade C-6-ELI has a typical yield strength of 720 MPa (104 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 53% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is Grade C-6-ELI easy to machine?
Not especially — machinability is rated poor (25/100, better than 53% of titanium grades). Machine like other alpha titanium: rigid setup, sharp uncoated-carbide or PVD tools, 25–45 m/min, heavy flood coolant, positive rake and no dwell — alpha case from casting must be removed by chem-mill/grinding before finish cuts.
Can Grade C-6-ELI be welded?
Yes — weldability is rated excellent (85/100). Readily GTAW/EBW/laser welded with matching filler under full argon or vacuum trailing/backing shielding; keep O+N pickup low, weld colour must be bright silver, and post-weld stress relieve 540–650 °C.
What surface finishes work on Grade C-6-ELI?
Chemical mill or grit blast plus pickle to remove shell and alpha case, then anodise (Type II colour / AMS 2488 Type III), chemical convert or dry-film lubricate; avoid chloride-bearing marking inks before elevated-temperature service.
Can Grade C-6-ELI be formed, bent or molded?
Supplied as investment or rammed-graphite castings from vacuum-arc skull or induction melting; allow generous shrink (~1.5 %), HIP to close shrinkage porosity — cold forming of the casting is not practical.
What is the maximum service temperature of Grade C-6-ELI?
Grade C-6-ELI is rated for continuous use to about 480°C (896 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Grade C-6 HIP+ANN and Grade C-6-ELI?
HIP+ANN is the default condition — standard aerospace/cryogenic casting delivery condition: densified, stress-free and dimensionally stable. ELI: specified for liquid-hydrogen/oxygen and other cryogenic hardware where toughness down to −253 °C matters more than room-temperature strength. Yield strength is 800 MPa in HIP+ANN versus 720 MPa in ELI.
Sources
- ASTM B367 — Titanium and Titanium Alloy Castings — ASTM International (2022)
- ASTM B265 — Titanium and Titanium Alloy Strip, Sheet and Plate (Grade 6) — ASTM International (2020)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Materials Properties Handbook: Titanium Alloys — ASM International (1994)
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.