Refractory Metal Zr 704-HW (Hot Worked / As-Forged)
Heat-treated state
UNS R60704 · ASTM B550/B551 Grade 704
Pick for heavy forged valve bodies and flanges where section size makes full annealing impractical.
Values for the HW condition
Other Zr 704 tempers and conditions
Zr 704 is listed in 4 conditions; see the grade overview at Zr 704.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault recrystallization annealed (mill standard for B550/B551/B523) | Default stocked condition for plate, sheet, bar and tube; best ductility and formability with guaranteed ASTM minimums. | 300 | 470 | 22 | 88 HRB | — |
As-welded deposit | Reference condition for design of welded Zr 704 vessels; strength close to base metal but ductility is reduced if shielding is imperfect. | 300 | 460 | 14 | 192 HB | 3.4 % IACS |
HWThis page Hot Worked / As-Forged | Pick for heavy forged valve bodies and flanges where section size makes full annealing impractical. | 320 | 480 | 18 | 185 HB | 3.4 % IACS |
Cold Worked and Stress Relieved | Choose for tubing, rod and fasteners needing higher strength and better dimensional stability than fully annealed material. | 480 | 600 | 14 | 20 HRC | 3.3 % IACS |
What is Zr 704-HW?
Zr 704-HW is Zr 704 heat treated to HW — pick for heavy forged valve bodies and flanges where section size makes full annealing impractical. Zr 704-HW has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 52% of refractory metal grades. Elongation at break is 18% and the elastic modulus is 99 GPa (14.4 Msi). Zr 704-HW has a density of 6.57 g/cm³ (0.237 lb/in³), lighter than 67% of refractory metal grades. It melts at 1,840°C (3,344 °F). Annealed is the default condition FabDigit quotes; HW is available on request or by drawing note.
Advantages
- Readily welded — 80/100, better than 92% of refractory metal grades
Limitations
- Poor heat conductor — 14.6 W/m·K (8.44 BTU/hr·ft·°F), worse than 84% of refractory metal grades
- Low stiffness — 99 GPa (14.4 Msi), worse than 79% of refractory metal grades
- High embodied carbon — 95 kg CO₂/kg, worse than 75% of refractory metal grades
Zr 704-HW properties
Typical room-temperature values for Zr 704-HW; 22 are specific to this condition. Other listed values are Zr 704 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
Zr 704-HW has a density of 6.57 g/cm³ (0.237 lb/in³), lighter than 67% of refractory metal grades. It melts at 1,840°C (3,344 °F).
Mechanical16
Zr 704-HW has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 52% of refractory metal grades. Elongation at break is 18% and the elastic modulus is 99 GPa (14.4 Msi).
Thermal6
Zr 704-HW is rated for continuous service to 400°C (752 °F). It conducts heat at 14.6 W/m·K (8.44 BTU/hr·ft·°F), worse than 84% of refractory metal grades. Thermal expansion is 6 µm/m·K (3.33 µin/in·°F).
Electrical3
Zr 704-HW conducts electricity at 3.4 % IACS, worse than 72% 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 704-HW takes about 1,400 MJ of energy and emits 95 kg of CO₂ — more than 67% of refractory metal grades. Typical recycled content is 20%.
Manufacturability8
Zr 704-HW's machinability is poor (32/100, better than 67% of refractory metal grades); weldability very good (80/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Zr 704-HW
Is Zr 704 easy to machine?
Use slow speeds, heavy positive-rake sharp carbide tooling and flood coolant; chips are pyrophoric — keep them wet and collect separately.
Can Zr 704 be welded?
GTAW/EBW with high-purity argon, trailing shield and back purge (<20 ppm O2/N2); a bright silver weld is acceptable, white or grey indicates contamination.
Can Zr 704 be formed, bent or molded?
Cold-form on generous radii (≥3–5t) with slow rams; warm forming at 200–400 °C improves bendability, and tools should be lubricated to avoid galling.
What surface finishes work on Zr 704?
Pickle in HNO3–HF to remove oxide and hydride skin after hot work; can be electropolished or anodized for colour, but avoid iron contamination from grinding media.
Zr 704 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 |
|---|---|---|
| Sn | 1 – 2 | 1.5 |
| Fe+Crcombined iron plus chromium | 0.2 – 0.4 | 0.3 |
| Hfhafnium is a natural companion of zirconium | ≤ 4.5 | 2 |
| O | ≤ 0.18 | 0.12 |
| C | ≤ 0.05 | 0.02 |
| N | ≤ 0.03 | 0.01 |
| H | ≤ 0.01 | 0 |
| Zr+Hfbalance zirconium plus hafnium | ≥ 97.5 (balance) | — |
Zr 704-HW — frequently asked
What is Zr 704-HW used for?
Zr 704-HW is typically used for process piping, heat exchanger tubing and chemical vessel components. In short: sn-strengthened zirconium; stronger than Zr 702; 400 °C acid-service grade.
What is the yield strength of Zr 704-HW?
Zr 704-HW has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 52% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is Zr 704-HW easy to machine?
Not especially — machinability is rated poor (32/100, better than 67% of refractory metal grades). Use slow speeds, heavy positive-rake sharp carbide tooling and flood coolant; chips are pyrophoric — keep them wet and collect separately.
Can Zr 704-HW be welded?
Yes — weldability is rated very good (80/100). GTAW/EBW with high-purity argon, trailing shield and back purge (<20 ppm O2/N2); a bright silver weld is acceptable, white or grey indicates contamination.
What surface finishes work on Zr 704-HW?
Pickle in HNO3–HF to remove oxide and hydride skin after hot work; can be electropolished or anodized for colour, but avoid iron contamination from grinding media.
Can Zr 704-HW be formed, bent or molded?
Cold-form on generous radii (≥3–5t) with slow rams; warm forming at 200–400 °C improves bendability, and tools should be lubricated to avoid galling.
What is the maximum service temperature of Zr 704-HW?
Zr 704-HW 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 704 Annealed and Zr 704 CW-SR?
Annealed is the default condition — default stocked condition for plate, sheet, bar and tube; best ductility and formability with guaranteed ASTM minimums. CW-SR: choose for tubing, rod and fasteners needing higher strength and better dimensional stability than fully annealed material. Yield strength is 300 MPa in Annealed versus 480 MPa in CW-SR.
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 and Welded Tube and Pipe — ASTM International (2022)
- Zirconium Alloys 702/704/705 technical data — ATI (Wah Chang) (2020)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
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.