Refractory Metal Zr 706
UNS R60706 · ASTM B550/B551 Grade 706
Zr 706 is the tighter-chemistry version of the niobium-bearing Zr 705, ordered to ASTM B550/B551 Grade 706 (UNS R60706) in annealed, cold-worked/stress-relieved, hot-worked or solution-treated-and-aged condition.
Reference datasheet — Zr 706 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 Annealed condition
Zr 706 tempers and conditions
Zr 706 is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
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 | — |
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?
Zr 706 is the tighter-chemistry version of the niobium-bearing Zr 705, ordered to ASTM B550/B551 Grade 706 (UNS R60706) in annealed, cold-worked/stress-relieved, hot-worked or solution-treated-and-aged condition. The restricted impurity and oxygen levels trade some strength — 400 MPa yield, 550 MPa tensile, 24% elongation, 180 HB (88 HRB) — for better formability (score 62) and weldability (75) than Zr 705, while holding about 400 °C service and a corrosion score of 88. Choose Zr 705 when maximum strength matters more than fabrication. Zr 706 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). Zr 706 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 63% of refractory metal grades. Elongation at break is 24% and the elastic modulus is 97 GPa (14.1 Msi).
What is Zr 706 used for?
- Critical chemical process components
- Corrosion-resistant reactor internals
- Specialty piping
Advantages
- Easy to machine — 40/100, better than 93% of refractory metal grades
- Readily welded — 75/100, better than 81% of refractory metal grades
Limitations
- Low stiffness — 97 GPa (14.1 Msi), worse than 91% 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 properties
Typical room-temperature values for Zr 706-Annealed; bars are the position among refractory metal grades.
Physical3
Zr 706 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 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 63% of refractory metal grades. Elongation at break is 24% and the elastic modulus is 97 GPa (14.1 Msi).
Thermal6
Zr 706 is rated for continuous service to 400°C (752 °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 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 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's machinability is fair (40/100, better than 93% of refractory metal grades); weldability very good (75/100); formability good (62/100).
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 refractory metal family
Yield strength against density for every refractory metal grade FabDigit runs. Zr 706 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Zr 706
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.
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) |
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.
Equivalent designations
Standards and trade names that resolve to Refractory Metal Zr 706 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R60706
- ASTM
- B550/B551 Grade 706
How much does Zr 706 cost?
Zr 706 is a high-cost refractory metal ($$$$), 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.
Zr 706 — frequently asked
What is Zr 706 used for?
Zr 706 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?
Zr 706 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 63% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is Zr 706 easy to machine?
Not especially — machinability is rated fair (40/100, better than 93% 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 be welded?
Yes — weldability is rated very good (75/100). 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?
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 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?
Zr 706 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 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.
How much does Zr 706 cost?
Zr 706 is a high-cost refractory metal ($$$$), 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 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; 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.