Refractory Metal C-129Y-SR (Stress relieved)
Heat-treated state
UNS R04360
Choose when higher room-temperature strength is wanted with usable ductility and dimensional stability after forming.
Values for the SR condition
Other C-129Y tempers and conditions
C-129Y is listed in 3 conditions; see the grade overview at C-129Y.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault recrystallization annealed sheet/plate (vacuum, ~1300–1500 °C) | Standard stocked condition for sheet and plate: best ductility and formability, baseline strength for hot-structure design. | 480 | 585 | 22 | 18 HRC | 3.6 % IACS |
SRThis page Stress relieved | Choose when higher room-temperature strength is wanted with usable ductility and dimensional stability after forming. | 620 | 700 | 12 | 24 HRC | 3.5 % IACS |
Cold worked | Maximum room-temperature strength for thin sheet, foil and wire where no high-temperature exposure will recrystallize the material. | 830 | 900 | 6 | 30 HRC | 3.4 % IACS |
What is C-129Y-SR?
C-129Y-SR is C-129Y heat treated to SR — choose when higher room-temperature strength is wanted with usable ductility and dimensional stability after forming. C-129Y-SR has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 84% of refractory metal grades. Elongation at break is 12% and the elastic modulus is 131 GPa (19 Msi). C-129Y-SR has a density of 9.46 g/cm³ (0.342 lb/in³), heavier than 59% of refractory metal grades. It melts at 2,450°C (4,442 °F). Annealed is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 72 MPa·√m (65.5 ksi·√in), better than 88% of refractory metal grades
- High strength — 620 MPa (89.9 ksi), better than 84% of refractory metal grades
- High service temperature — 1,300°C (2,372 °F), better than 76% of refractory metal grades
C-129Y-SR properties
Typical room-temperature values for C-129Y-SR; 23 are specific to this condition. Other listed values are C-129Y reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
C-129Y-SR has a density of 9.46 g/cm³ (0.342 lb/in³), heavier than 59% of refractory metal grades. It melts at 2,450°C (4,442 °F).
Mechanical17
C-129Y-SR has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 84% of refractory metal grades. Elongation at break is 12% and the elastic modulus is 131 GPa (19 Msi).
Thermal6
C-129Y-SR is rated for continuous service to 1,300°C (2,372 °F). It conducts heat at 31 W/m·K (17.9 BTU/hr·ft·°F), worse than 59% of refractory metal grades. Thermal expansion is 7.5 µm/m·K (4.17 µin/in·°F).
Electrical3
C-129Y-SR conducts electricity at 3.5 % IACS, worse than 70% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), worse than 63% of refractory metal grades.
Sustainability4
Producing a kilogram of C-129Y-SR takes about 620 MJ of energy and emits 42 kg of CO₂ — less than 67% of refractory metal grades. Typical recycled content is 25%.
Manufacturability7
C-129Y-SR's machinability is poor (22/100, worse than 73% of refractory metal grades); weldability good (65/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C-129Y-SR
Is C-129Y easy to machine?
Machine slow with sharp, positive-rake carbide or HSS-Co tooling, heavy rigid setups and flood coolant; it work-hardens and galls, so avoid dwell and take positive chip loads.
Can C-129Y be welded?
GTAW or EB weld in vacuum or high-purity argon with full backside shielding — oxygen/nitrogen pickup embrittles the weld; clean and degrease thoroughly and post-weld vacuum anneal where possible.
Can C-129Y be formed, bent or molded?
Sheet forms readily cold in the annealed condition with generous bend radii; heavy sections are worked warm (600–1000 °C) and vacuum annealed between passes.
What surface finishes work on C-129Y?
Chemically clean (HNO₃-HF pickle) then apply a fused silicide coating such as R512E for oxidation protection; decorative anodizing is possible but has no service value.
C-129Y 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 |
|---|---|---|
| Wsolid-solution strengthener | 9 – 11 | 10 |
| Hfcarbide/oxide strengthening, coating adherence | 9 – 11 | 10 |
| Yinterstitial scavenger | 0.05 – 0.15 | 0.1 |
| Zrresidual from Hf | ≤ 0.5 | — |
| Taresidual | ≤ 0.5 | — |
| C | ≤ 0.03 | 0.01 |
| O | ≤ 0.02 | 0.01 |
| N | ≤ 0.01 | 0.01 |
| H | ≤ 0 | — |
| Fe | ≤ 0.05 | — |
| Nb | balance | — |
C-129Y-SR — frequently asked
What is C-129Y-SR used for?
C-129Y-SR is typically used for rocket nozzle extensions, high-temperature structural panels and re-entry vehicle components. In short: stronger creep than C-103; yttrium-doped Nb-W-Hf sheet; needs silicide coating in air.
What is the yield strength of C-129Y-SR?
C-129Y-SR has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 84% of refractory metal grades. Strength varies by condition: see the 3 listed tempers.
Is C-129Y-SR easy to machine?
Not especially — machinability is rated poor (22/100, worse than 73% of refractory metal grades). Machine slow with sharp, positive-rake carbide or HSS-Co tooling, heavy rigid setups and flood coolant; it work-hardens and galls, so avoid dwell and take positive chip loads.
Can C-129Y-SR be welded?
Yes — weldability is rated good (65/100). GTAW or EB weld in vacuum or high-purity argon with full backside shielding — oxygen/nitrogen pickup embrittles the weld; clean and degrease thoroughly and post-weld vacuum anneal where possible.
What surface finishes work on C-129Y-SR?
Chemically clean (HNO₃-HF pickle) then apply a fused silicide coating such as R512E for oxidation protection; decorative anodizing is possible but has no service value.
Can C-129Y-SR be formed, bent or molded?
Sheet forms readily cold in the annealed condition with generous bend radii; heavy sections are worked warm (600–1000 °C) and vacuum annealed between passes.
What is the maximum service temperature of C-129Y-SR?
C-129Y-SR is rated for continuous use to about 1,300°C (2,372 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C-129Y Annealed and C-129Y-CW?
Annealed is the default condition — standard stocked condition for sheet and plate: best ductility and formability, baseline strength for hot-structure design. CW: maximum room-temperature strength for thin sheet, foil and wire where no high-temperature exposure will recrystallize the material. Yield strength is 480 MPa in Annealed versus 830 MPa in CW.
Sources
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, refractory metals section — ASM International (1990)
- Aerospace Structural Metals Handbook — niobium (columbium) alloys — CINDAS/Purdue (1999)
- ASTM B652/B654 — Niobium-alloy bar, rod, sheet, strip and foil — ASTM International (2019)
- Refractory metal alloy datasheets (Nb-10W-10Hf-0.1Y, C-103, Cb-752) — specialty refractory metal producers (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.