Titanium Grade C-6
ASTM B367 Grade C-6
Grade C-6 is an alpha-alloy titanium casting grade in the ASTM B367 family, providing stable strength from cryogenic temperatures up to about 480 °C along with good weldability.
Reference datasheet — Grade C-6 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+ANN condition
Grade C-6 tempers and conditions
Grade C-6 is supplied in 5 conditions, soft to hard. HIP+ANN 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 |
|---|---|---|---|---|---|---|
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?
Grade C-6 is an alpha-alloy titanium casting grade in the ASTM B367 family, providing stable strength from cryogenic temperatures up to about 480 °C along with good weldability. Supplied as investment or rammed-graphite castings, it delivers 800 MPa yield, 860 MPa tensile, 12 % elongation and 295 HB (31 HRC), which suits cryogenic tank fittings and hot ducting where the beta-stabilized C-5 alloy is not required. Ductility is limited, machinability is low (score 22), and casting porosity normally has to be closed by HIP; C-5 remains the higher-strength alternative and C-2 the more ductile one. Grade C-6 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). Grade C-6 has a yield strength of 800 MPa (116 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 57% of titanium grades. Elongation at break is 12% and the elastic modulus is 110 GPa (16 Msi).
What is Grade C-6 used for?
- cryogenic tankage fittings
- aerospace ducting castings
- pressure vessel components
Advantages
- 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 — 15/100, worse than 93% of titanium grades
- Limited ductility — 12%, worse than 78% of titanium grades
Grade C-6 properties
Typical room-temperature values for Grade C-6-HIP+ANN; bars are the position among titanium grades.
Physical3
Grade C-6 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 has a yield strength of 800 MPa (116 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 57% of titanium grades. Elongation at break is 12% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
Grade C-6 is rated for continuous service to 480°C (896 °F). It conducts heat at 7.8 W/m·K (4.51 BTU/hr·ft·°F), worse than 53% of titanium grades. Thermal expansion is 9.4 µm/m·K (5.22 µin/in·°F).
Electrical3
Grade C-6 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 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's machinability is poor (22/100, worse than 55% of titanium grades); weldability very good (80/100); formability poor (15/100).
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. Grade C-6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Grade C-6
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.
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 |
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.
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 Grade C-6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- B367 Grade C-6
How much does Grade C-6 cost?
Grade C-6 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.
Grade C-6 — frequently asked
What is Grade C-6 used for?
Grade C-6 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?
Grade C-6 has a typical yield strength of 800 MPa (116 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 57% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is Grade C-6 easy to machine?
Not especially — machinability is rated poor (22/100, worse than 55% 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 be welded?
Yes — weldability is rated very good (80/100). 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?
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 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?
Grade C-6 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.
How much does Grade C-6 cost?
Grade C-6 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 — 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; 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.