Titanium C-12-SR (Stress relieved)
Heat-treated state
ASTM B367 Grade C-12
Pick when casting is heavily weld-repaired or machined and residual stress/distortion must be controlled without full anneal.
Values for the SR condition
Other C-12 tempers and conditions
C-12 is listed in 5 conditions; see the grade overview at C-12.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Lowest-cost condition for non-critical, low-stress corrosion hardware where internal porosity is acceptable. | 450 | 550 | 10 | 215 HB | 3.3 % IACS |
SRThis page Stress relieved | Pick when casting is heavily weld-repaired or machined and residual stress/distortion must be controlled without full anneal. | 450 | 555 | 11 | 210 HB | 3.3 % IACS |
ADefault Solution annealed | Standard supply condition for ASTM B367 C-12 castings: stable microstructure, best ductility-to-strength balance for chemical plant service. | 455 | 560 | 12 | 210 HB | 3.3 % IACS |
Hot isostatically pressed and annealed | Highest-integrity condition: HIP densification followed by anneal to relieve HIP-cycle stresses and stabilise properties. | 455 | 565 | 17 | 205 HB | 3.3 % IACS |
Hot isostatic pressed | Choose for pressure-boundary or fatigue-loaded castings: closes internal porosity and lifts ductility and fatigue life. | 460 | 570 | 16 | 210 HB | 3.3 % IACS |
What is C-12-SR?
C-12-SR is C-12 heat treated to SR — pick when casting is heavily weld-repaired or machined and residual stress/distortion must be controlled without full anneal. C-12-SR has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 555 MPa (80.5 ksi) — weaker than 65% of titanium grades. Elongation at break is 11% and the elastic modulus is 103 GPa (14.9 Msi). C-12-SR has a density of 4.51 g/cm³ (0.163 lb/in³), heavier than 57% of titanium grades. It melts at 1,650°C (3,002 °F). A is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Conducts heat well — 19 W/m·K (11 BTU/hr·ft·°F), better than 93% of titanium grades
- High electrical conductivity — 3.3 % IACS, better than 92% of titanium grades
Limitations
- Limited ductility — 11%, worse than 87% of titanium grades
C-12-SR properties
Typical room-temperature values for C-12-SR; 22 are specific to this condition. Other listed values are C-12 reference data and may not represent this condition. Bars are the position among titanium grades.
Physical3
C-12-SR has a density of 4.51 g/cm³ (0.163 lb/in³), heavier than 57% of titanium grades. It melts at 1,650°C (3,002 °F).
Mechanical16
C-12-SR has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 555 MPa (80.5 ksi) — weaker than 65% of titanium grades. Elongation at break is 11% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
C-12-SR is rated for continuous service to 315°C (599 °F). It conducts heat at 19 W/m·K (11 BTU/hr·ft·°F), better than 93% of titanium grades. Thermal expansion is 9.5 µm/m·K (5.28 µin/in·°F).
Electrical3
C-12-SR conducts electricity at 3.3 % IACS, better than 92% of titanium grades.
Chemical & Environmental3
Corrosion resistance is excellent (93/100), better than 72% of titanium grades.
Sustainability4
Producing a kilogram of C-12-SR takes about 700 MJ of energy and emits 42 kg of CO₂ — more than 74% of titanium grades. Typical recycled content is 25%.
Manufacturability8
C-12-SR's machinability is poor (28/100, better than 59% of titanium grades); weldability excellent (85/100); formability poor (27/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C-12-SR
Is C-12 easy to machine?
Machine like CP Ti but slightly harder: low surface speed (25–45 m/min carbide), heavy positive rake, rigid setup, flood coolant and never dwell — chips are pyrophoric and work-hardening/galling is the main failure mode.
Can C-12 be welded?
Excellent GTAW/EBW weldability with matching Gr12 filler; requires full argon/helium shielding of pool, root and trailing HAZ, cleanliness to avoid O/N/H pickup, and interpass temperature below ~200 °C; weld repair of castings is routine and re-HIP is common after major repair.
Can C-12 be formed, bent or molded?
Supplied as vacuum-melted (VAR/skull) castings poured into rammed-graphite or investment moulds under vacuum/argon; allow generous machining stock for the alpha-case layer and specify HIP for pressure-containing parts.
What surface finishes work on C-12?
Remove alpha case by chemical milling (HNO3/HF) or grit blast + pickle before service; anodizing (colour or Type III) and passivation are effective, and surfaces polish well although casting porosity can show.
C-12 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 |
|---|---|---|
| Mo | 0.2 – 0.4 | 0.3 |
| Ni | 0.6 – 0.9 | 0.8 |
| Fe | ≤ 0.3 | 0.15 |
| O | ≤ 0.25 | 0.18 |
| C | ≤ 0.08 | 0.03 |
| N | ≤ 0.03 | 0.02 |
| Hmax (castings) | ≤ 0.02 | 0.01 |
| Residuals, eachmax each | ≤ 0.1 | — |
| Residuals, totalmax total | ≤ 0.4 | — |
| Ti | balance | — |
C-12-SR — frequently asked
What is C-12-SR used for?
C-12-SR is typically used for seawater piping components, heat-exchanger castings and chemical process housings. In short: low-cost crevice-corrosion cast titanium; excellent weldability; alternative to Grade 7.
What is the yield strength of C-12-SR?
C-12-SR has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 555 MPa (80.5 ksi) — weaker than 65% of titanium grades. Strength varies by condition: see the 5 listed tempers.
Is C-12-SR easy to machine?
Not especially — machinability is rated poor (28/100, better than 59% of titanium grades). Machine like CP Ti but slightly harder: low surface speed (25–45 m/min carbide), heavy positive rake, rigid setup, flood coolant and never dwell — chips are pyrophoric and work-hardening/galling is the main failure mode.
Can C-12-SR be welded?
Yes — weldability is rated excellent (85/100). Excellent GTAW/EBW weldability with matching Gr12 filler; requires full argon/helium shielding of pool, root and trailing HAZ, cleanliness to avoid O/N/H pickup, and interpass temperature below ~200 °C; weld repair of castings is routine and re-HIP is common after major repair.
What surface finishes work on C-12-SR?
Remove alpha case by chemical milling (HNO3/HF) or grit blast + pickle before service; anodizing (colour or Type III) and passivation are effective, and surfaces polish well although casting porosity can show.
Can C-12-SR be formed, bent or molded?
Supplied as vacuum-melted (VAR/skull) castings poured into rammed-graphite or investment moulds under vacuum/argon; allow generous machining stock for the alpha-case layer and specify HIP for pressure-containing parts.
What is the maximum service temperature of C-12-SR?
C-12-SR is rated for continuous use to about 315°C (599 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C-12-A and C-12-F?
A is the default condition — standard supply condition for ASTM B367 C-12 castings: stable microstructure, best ductility-to-strength balance for chemical plant service. F: lowest-cost condition for non-critical, low-stress corrosion hardware where internal porosity is acceptable. Yield strength is 455 MPa in A versus 450 MPa in F.
Sources
- ASTM B367 Standard Specification for Titanium and Titanium Alloy Castings — ASTM International (2022)
- ASTM B265 / B348 Titanium Grade 12 (wrought reference) — ASTM International (2020)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Materials Properties Handbook: Titanium Alloys — ASM International (1994)
- TIMETAL Code 12 (Ti-0.3Mo-0.8Ni) corrosion and property data — TIMET (2018)
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.