Refractory Metal Zr 706 CWSR
Heat-treated state
UNS R60706 · ASTM B550/B551 Grade 706
CWSR = cold worked and stress relieved
Pick for tube and bar needing higher strength and stiffness-limited sections; ductility and formability are reduced.
Values for the CWSR condition
Other Zr 706 tempers and conditions
Zr 706 is listed in 4 conditions; see the grade overview at Zr 706.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot worked / as-forged | Economical condition for heavy forged bar, flanges and valve bodies where a full anneal is not specified. | 390 | 545 | 21 | 176 HB | 3.1 % IACS |
AnnealedDefault recrystallization annealed (ASTM B550/B551/B523 standard condition) | Default stocked condition for plate, sheet, bar and tube; best ductility and formability with full corrosion resistance. | 400 | 550 | 24 | 180 HB | — |
CWSRThis page Cold worked and stress relieved | Pick for tube and bar needing higher strength and stiffness-limited sections; ductility and formability are reduced. | 550 | 660 | 14 | 96 HRB | — |
Solution treated and aged | Special-order high-strength condition for fasteners and small structural parts; corrosion resistance and toughness drop and it is rarely used for pressure vessels. | 750 | 900 | 10 | 32 HRC | — |
What is Zr 706 CWSR?
Zr 706 CWSR is Zr 706 heat treated to CWSR — pick for tube and bar needing higher strength and stiffness-limited sections; ductility and formability are reduced. Zr 706 CWSR has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 76% of refractory metal grades. Elongation at break is 14% and the elastic modulus is 97 GPa (14.1 Msi). Zr 706 CWSR has a density of 6.64 g/cm³ (0.24 lb/in³), lighter than 63% of refractory metal grades. It melts at 1,840°C (3,344 °F). Annealed is the default condition FabDigit quotes; CWSR is available on request or by drawing note.
Advantages
- Easy to machine — 45/100, better than 99% of refractory metal grades
- High strength — 550 MPa (79.8 ksi), better than 76% of refractory metal grades
Limitations
- Low stiffness — 97 GPa (14.1 Msi), worse than 91% of refractory metal grades
- Limited service temperature — 350°C (662 °F), worse than 89% of refractory metal grades
- Low electrical conductivity — 3.1 % IACS, worse than 78% of refractory metal grades
- Poor heat conductor — 17.1 W/m·K (9.88 BTU/hr·ft·°F), worse than 76% of refractory metal grades
Zr 706 CWSR properties
Typical room-temperature values for Zr 706 CWSR; 11 are specific to this condition. Other listed values are Zr 706 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
Zr 706 CWSR has a density of 6.64 g/cm³ (0.24 lb/in³), lighter than 63% of refractory metal grades. It melts at 1,840°C (3,344 °F).
Mechanical16
Zr 706 CWSR has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 76% of refractory metal grades. Elongation at break is 14% and the elastic modulus is 97 GPa (14.1 Msi).
Thermal6
Zr 706 CWSR is rated for continuous service to 350°C (662 °F). It conducts heat at 17.1 W/m·K (9.88 BTU/hr·ft·°F), worse than 76% of refractory metal grades. Thermal expansion is 6 µm/m·K (3.33 µin/in·°F).
Electrical3
Zr 706 CWSR conducts electricity at 3.1 % IACS, worse than 78% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 64% of refractory metal grades.
Sustainability4
Producing a kilogram of Zr 706 CWSR takes about 1,300 MJ of energy and emits 78 kg of CO₂ — more than 57% of refractory metal grades. Typical recycled content is 20%.
Manufacturability8
Zr 706 CWSR's machinability is fair (45/100, better than 99% of refractory metal grades); weldability very good (70/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Zr 706 CWSR
Is Zr 706 easy to machine?
Machine like a gummy austenitic stainless — sharp carbide tools, heavy positive rake, slow speed with high feed and flood coolant; never let fine chips accumulate dry (pyrophoric).
Can Zr 706 be welded?
GTAW/plasma or EB with high-purity argon/helium plus trailing shields or a chamber; keep the weld and HAZ below ~200 ppm oxygen pickup and expect bright silver, not straw or blue, welds.
Can Zr 706 be formed, bent or molded?
The low-oxygen 706 chemistry cold-bends and dishes well with generous radii (≥3t) and slow ram speeds; hot form 700–800 °C in inert conditions and pickle scale in HNO3-HF afterwards.
What surface finishes work on Zr 706?
Mechanically polish or abrasive-blast then pickle/passivate for a stable oxide; anodic colouring is possible, and avoid embedding iron from steel tooling to prevent rust staining and localized attack.
Zr 706 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 |
|---|---|---|
| Nbcolumbium (niobium) | 2 – 3 | 2.5 |
| Hfhafnium not removed (industrial, non-nuclear grade) | ≤ 4.5 | 2 |
| Fe+Cr | ≤ 0.2 | 0.1 |
| Otighter than Zr 705 (0.18 max) — source of the higher ductility | ≤ 0.16 | 0.11 |
| C | ≤ 0.05 | 0.02 |
| N | ≤ 0.03 | 0.01 |
| H | ≤ 0.01 | 0 |
| Zr+HfZr+Hf minimum per ASTM B550/B551 | ≥ 95.5 (balance) | — |
Zr 706 CWSR — frequently asked
What is Zr 706 CWSR used for?
Zr 706 CWSR is typically used for critical chemical process components, corrosion-resistant reactor internals and specialty piping. In short: formable Nb zirconium; tighter-chemistry Zr 705; weldable high-strength Zr.
What is the yield strength of Zr 706 CWSR?
Zr 706 CWSR has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 76% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is Zr 706 CWSR easy to machine?
Reasonably — machinability is rated fair (45/100, better than 99% of refractory metal grades). Machine like a gummy austenitic stainless — sharp carbide tools, heavy positive rake, slow speed with high feed and flood coolant; never let fine chips accumulate dry (pyrophoric).
Can Zr 706 CWSR be welded?
Yes — weldability is rated very good (70/100). GTAW/plasma or EB with high-purity argon/helium plus trailing shields or a chamber; keep the weld and HAZ below ~200 ppm oxygen pickup and expect bright silver, not straw or blue, welds.
What surface finishes work on Zr 706 CWSR?
Mechanically polish or abrasive-blast then pickle/passivate for a stable oxide; anodic colouring is possible, and avoid embedding iron from steel tooling to prevent rust staining and localized attack.
Can Zr 706 CWSR be formed, bent or molded?
The low-oxygen 706 chemistry cold-bends and dishes well with generous radii (≥3t) and slow ram speeds; hot form 700–800 °C in inert conditions and pickle scale in HNO3-HF afterwards.
What is the maximum service temperature of Zr 706 CWSR?
Zr 706 CWSR is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Zr 706 Annealed and Zr 706-STA?
Annealed is the default condition — default stocked condition for plate, sheet, bar and tube; best ductility and formability with full corrosion resistance. STA: special-order high-strength condition for fasteners and small structural parts; corrosion resistance and toughness drop and it is rarely used for pressure vessels. Yield strength is 400 MPa in Annealed versus 750 MPa in STA.
Sources
- ASTM B550/B550M — Zirconium and Zirconium Alloy Bar and Wire — ASTM International (2020)
- ASTM B551/B551M — Zirconium and Zirconium Alloy Strip, Sheet and Plate — ASTM International (2019)
- ASTM B523/B658 — Zirconium and Zirconium Alloy Seamless and Welded Tube/Pipe — ASTM International (2020)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (Zirconium and Hafnium) — ASM International (1990)
- Zirconium alloy 702/705 industrial grade property sheets — ATI / Wah Chang (2015)
- Corrosion of Zirconium and Zirconium Alloys (ASM Corrosion Handbook Vol. 13B) — ASM International (2005)
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.