Refractory Metal Zr 702-HW (Hot worked)
Heat-treated state
UNS R60702 · ASTM B550/B551 Grade 702
Economical condition for heavy forged sections and thick plate before final annealing; slightly higher strength, coarser structure than annealed.
Values for the HW condition
Other Zr 702 tempers and conditions
Zr 702 is listed in 5 conditions; see the grade overview at Zr 702.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As-welded deposit | Property basis for fabricated vessels and pipe joints welded with full inert shielding; coarse weld-metal grain lowers ductility slightly, strength matches base metal. | 280 | 450 | 18 | 165 HB | 4.3 % IACS |
AnnealedDefault recrystallization annealed (ASTM B550/B551/B523/B658 standard condition) | Default stocked condition for plate, sheet, bar, pipe and tube in chemical-process service; best ductility, formability and corrosion behaviour. | 290 | 450 | 30 | 150 HB | — |
HWThis page Hot worked | Economical condition for heavy forged sections and thick plate before final annealing; slightly higher strength, coarser structure than annealed. | 330 | 480 | 25 | 165 HB | 4.3 % IACS |
Cold worked and stress relieved | Pick for cold-drawn tubing and pipe where higher strength and tight dimensional control are needed while retaining useful ductility. | 450 | 550 | 18 | 95 HRB | — |
Cold worked | Highest strength condition of Zr 702; used for fasteners, springs, wire and machined parts where ductility demands are modest. | 550 | 620 | 12 | 100 HRB | — |
What is Zr 702-HW?
Zr 702-HW is Zr 702 heat treated to HW — economical condition for heavy forged sections and thick plate before final annealing; slightly higher strength, coarser structure than annealed. Zr 702-HW has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 50% of refractory metal grades. Elongation at break is 25% and the elastic modulus is 99 GPa (14.4 Msi). Zr 702-HW has a density of 6.51 g/cm³ (0.235 lb/in³), lighter than 84% of refractory metal grades. It melts at 1,852°C (3,366 °F). Annealed is the default condition FabDigit quotes; HW is available on request or by drawing note.
Advantages
- Readily welded — 78/100, better than 86% of refractory metal grades
- Lightweight — 6.51 g/cm³ (0.235 lb/in³), better than 84% of refractory metal grades
- Tough — resists crack growth — 62 MPa·√m (56.4 ksi·√in), better than 80% of refractory metal grades
Limitations
- Limited service temperature — 371°C (700 °F), worse than 87% of refractory metal grades
- Low stiffness — 99 GPa (14.4 Msi), worse than 79% of refractory metal grades
Zr 702-HW properties
Typical room-temperature values for Zr 702-HW; 22 are specific to this condition. Other listed values are Zr 702 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
Zr 702-HW has a density of 6.51 g/cm³ (0.235 lb/in³), lighter than 84% of refractory metal grades. It melts at 1,852°C (3,366 °F).
Mechanical16
Zr 702-HW has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 50% of refractory metal grades. Elongation at break is 25% and the elastic modulus is 99 GPa (14.4 Msi).
Thermal6
Zr 702-HW is rated for continuous service to 371°C (700 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 66% of refractory metal grades. Thermal expansion is 5.9 µm/m·K (3.28 µin/in·°F).
Electrical3
Zr 702-HW conducts electricity at 4.3 % IACS, worse than 62% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (92/100), better than 86% of refractory metal grades.
Sustainability4
Producing a kilogram of Zr 702-HW takes about 1,250 MJ of energy and emits 85 kg of CO₂ — more than 52% of refractory metal grades. Typical recycled content is 15%.
Manufacturability8
Zr 702-HW's machinability is poor (34/100, better than 73% of refractory metal grades); weldability very good (78/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Zr 702-HW
Is Zr 702 easy to machine?
Machine like a gummy austenitic stainless — sharp uncoated carbide, slow speeds, heavy positive rake, generous flood coolant; collect chips wet, fine turnings and grinding dust are pyrophoric.
Can Zr 702 be welded?
GTAW (or EB/plasma) with high-purity argon plus trailing shield and back purge; keep the weld and HAZ bright-silver — straw/blue/grey tint means oxygen pickup and must be removed.
Can Zr 702 be formed, bent or molded?
Cold forms readily at 3–5t bend radii but springs back strongly; warm forming at 200–350 °C is used for tight bends and heads, and hydrogen/oxygen pickup must be avoided in any heating.
What surface finishes work on Zr 702?
Pickle in HNO3–HF to remove oxide/contaminated layers, then descale-free passivation; can be electropolished or anodized to coloured oxide, avoid iron contamination from steel tooling.
Zr 702 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 |
|---|---|---|
| Hfmax per ASTM B550/B551 | ≤ 4.5 | 2 |
| Fe+Cr | ≤ 0.2 | 0.1 |
| Oprincipal strengthening interstitial | ≤ 0.16 | 0.1 |
| C | ≤ 0.05 | 0.02 |
| N | ≤ 0.03 | 0.01 |
| Hhydrogen embrittlement control | ≤ 0.01 | 0 |
| Zr+HfHf is not removed in commercial grade | ≥ 99.2 (balance) | — |
Zr 702-HW — frequently asked
What is Zr 702-HW used for?
Zr 702-HW is typically used for acid plant piping, heat exchangers, chemical reactor vessels and nuclear-adjacent process equipment. In short: default corrosion-service zirconium; handles hot acids and alkalis; weldable and cold formable.
What is the yield strength of Zr 702-HW?
Zr 702-HW has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 50% of refractory metal grades. Strength varies by condition: see the 5 listed tempers.
Is Zr 702-HW easy to machine?
Not especially — machinability is rated poor (34/100, better than 73% of refractory metal grades). Machine like a gummy austenitic stainless — sharp uncoated carbide, slow speeds, heavy positive rake, generous flood coolant; collect chips wet, fine turnings and grinding dust are pyrophoric.
Can Zr 702-HW be welded?
Yes — weldability is rated very good (78/100). GTAW (or EB/plasma) with high-purity argon plus trailing shield and back purge; keep the weld and HAZ bright-silver — straw/blue/grey tint means oxygen pickup and must be removed.
What surface finishes work on Zr 702-HW?
Pickle in HNO3–HF to remove oxide/contaminated layers, then descale-free passivation; can be electropolished or anodized to coloured oxide, avoid iron contamination from steel tooling.
Can Zr 702-HW be formed, bent or molded?
Cold forms readily at 3–5t bend radii but springs back strongly; warm forming at 200–350 °C is used for tight bends and heads, and hydrogen/oxygen pickup must be avoided in any heating.
What is the maximum service temperature of Zr 702-HW?
Zr 702-HW is rated for continuous use to about 371°C (700 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Zr 702 Annealed and Zr 702-CW?
Annealed is the default condition — default stocked condition for plate, sheet, bar, pipe and tube in chemical-process service; best ductility, formability and corrosion behaviour. CW: highest strength condition of Zr 702; used for fasteners, springs, wire and machined parts where ductility demands are modest. Yield strength is 290 MPa in Annealed versus 550 MPa in CW.
Sources
- ASTM B551/B551M — Zirconium and Zirconium Alloy Strip, Sheet, and Plate — ASTM International (2019)
- ASTM B550/B550M — Zirconium and Zirconium Alloy Bar and Wire — ASTM International (2020)
- ASTM B523 / B658 — Zirconium alloy seamless tube and pipe — ASTM International (2020)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (Zirconium and Hafnium) — ASM International (1990)
- Zirconium 702 alloy data and corrosion tables — ATI (Wah Chang) (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.