Refractory Metal R02002-SR (Stress relieved)
Heat-treated state
UNS R02002 · ASTM B776 Grade 2, B737 Grade 2
Compromise condition: keeps most cold-work strength while removing residual stress and distortion after machining.
Values for the SR condition
Other R02002 tempers and conditions
R02002 is listed in 4 conditions; see the grade overview at R02002.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Default stocked condition: maximum ductility for forming, welding and machining of plasma electrodes and chemical parts. | 240 | 450 | 25 | 165 HB | — |
Hot Worked | Economical heavy-section form for further machining or re-melt stock; surface carries oxide/alpha case and is normally conditioned. | 310 | 500 | 20 | 185 HB | 5 % IACS |
SRThis page Stress relieved | Compromise condition: keeps most cold-work strength while removing residual stress and distortion after machining. | 500 | 620 | 12 | 19 HRC | 5.1 % IACS |
Cold worked | Choose when higher strength, straightness and surface finish are needed and no severe forming follows. | 620 | 700 | 6 | 23 HRC | 5 % IACS |
What is R02002-SR?
R02002-SR is R02002 heat treated to SR — compromise condition: keeps most cold-work strength while removing residual stress and distortion after machining. R02002-SR has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 75% of refractory metal grades. Elongation at break is 12% and the elastic modulus is 138 GPa (20 Msi). R02002-SR has a density of 13.31 g/cm³ (0.481 lb/in³), heavier than 77% of refractory metal grades. It melts at 2,233°C (4,051 °F). ANN is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- High strength — 500 MPa (72.5 ksi), better than 75% of refractory metal grades
Limitations
- High embodied carbon — 130 kg CO₂/kg, worse than 83% of refractory metal grades
- Heavy — 13.31 g/cm³ (0.481 lb/in³), worse than 77% of refractory metal grades
R02002-SR properties
Typical room-temperature values for R02002-SR; 22 are specific to this condition. Other listed values are R02002 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
R02002-SR has a density of 13.31 g/cm³ (0.481 lb/in³), heavier than 77% of refractory metal grades. It melts at 2,233°C (4,051 °F).
Mechanical12
R02002-SR has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 75% of refractory metal grades. Elongation at break is 12% and the elastic modulus is 138 GPa (20 Msi).
Thermal6
R02002-SR is rated for continuous service to 400°C (752 °F). It conducts heat at 23 W/m·K (13.3 BTU/hr·ft·°F), worse than 61% of refractory metal grades. Thermal expansion is 5.9 µm/m·K (3.28 µin/in·°F).
Electrical3
R02002-SR conducts electricity at 5.1 % IACS, worse than 58% of refractory metal grades.
Chemical & Environmental2
Corrosion resistance is excellent (85/100), better than 52% of refractory metal grades.
Sustainability3
Producing a kilogram of R02002-SR takes about 2,000 MJ of energy and emits 130 kg of CO₂ — more than 83% of refractory metal grades. Typical recycled content is 20%.
Manufacturability8
R02002-SR's machinability is poor (33/100, better than 71% of refractory metal grades); weldability good (65/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with R02002-SR
Is R02002 easy to machine?
Machine like zirconium: slow speed, heavy positive-rake sharp carbide, deep cuts, flood coolant — never dry; collect chips wet, they are pyrophoric.
Can R02002 be welded?
GTAW/EB/laser only with full inert (Ar/He) chamber or trailing-shield coverage; keep O/N/H pickup low or the weld embrittles.
Can R02002 be formed, bent or molded?
Cold form annealed sheet with 3–5t bend radii and polished dies to avoid galling; warm form 200–400 °C for tighter radii, then stress relieve.
What surface finishes work on R02002?
Pickle in HNO3/HF to strip oxide and alpha case; passivates naturally in air, can be electropolished or anodized for colour; no plating normally required.
R02002 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 |
|---|---|---|
| ZrResidual zirconium; commercial grade may exceed reactor-grade practice — confirm with purchase order | ≤ 4.5 | 2.5 |
| OMain strengthening interstitial | ≤ 0.2 | 0.1 |
| C | ≤ 0.03 | 0.01 |
| N | ≤ 0.01 | 0 |
| H | ≤ 0.01 | 0 |
| Fe+Cr | ≤ 0.25 | 0.1 |
| Al | ≤ 0.01 | 0 |
| Ti | ≤ 0.05 | 0.01 |
| UNot restricted for commercial grade (restricted only in nuclear grade R02001) | — | — |
| HfHf + Zr reported together; Hf/Zr ratio not restricted for commercial grade | balance | — |
R02002-SR — frequently asked
What is R02002-SR used for?
R02002-SR is typically used for plasma cutting electrode tips, getter alloys, high-temperature coatings and cermets, superalloy additive and research and specialty tooling. In short: cheaper non-nuclear hafnium; unrestricted Hf/Zr ratio; plasma electrode grade.
What is the yield strength of R02002-SR?
R02002-SR has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 75% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is R02002-SR easy to machine?
Not especially — machinability is rated poor (33/100, better than 71% of refractory metal grades). Machine like zirconium: slow speed, heavy positive-rake sharp carbide, deep cuts, flood coolant — never dry; collect chips wet, they are pyrophoric.
Can R02002-SR be welded?
Yes — weldability is rated good (65/100). GTAW/EB/laser only with full inert (Ar/He) chamber or trailing-shield coverage; keep O/N/H pickup low or the weld embrittles.
What surface finishes work on R02002-SR?
Pickle in HNO3/HF to strip oxide and alpha case; passivates naturally in air, can be electropolished or anodized for colour; no plating normally required.
Can R02002-SR be formed, bent or molded?
Cold form annealed sheet with 3–5t bend radii and polished dies to avoid galling; warm form 200–400 °C for tighter radii, then stress relieve.
What is the maximum service temperature of R02002-SR?
R02002-SR 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 R02002-ANN and R02002-CW?
ANN is the default condition — default stocked condition: maximum ductility for forming, welding and machining of plasma electrodes and chemical parts. CW: choose when higher strength, straightness and surface finish are needed and no severe forming follows. Yield strength is 240 MPa in ANN versus 620 MPa in CW.
Sources
- ASTM B776 — Standard Specification for Hafnium and Hafnium Alloy Strip, Sheet, and Plate — ASTM International (2021)
- ASTM B737 — Standard Specification for Hafnium and Hafnium Alloy Bar, Rod, and Wire — ASTM International (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- CRC Handbook of Chemistry and Physics (hafnium physical constants) — CRC Press (2022)
- Hafnium metal mill products datasheet — ATI Wah Chang (2015)
- Mineral Commodity Summaries — Hafnium/Zirconium — USGS (2025)
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.