Zirconium and Zircaloy Zr

spore: profile
id: zirconium
spore_version: 0.2
family: refractory-metals
name: Zirconium and Zircaloy
abbreviation: Zr
role: corrosion-resistant structural metal and nuclear cladding alloy
category: metals
type: refractory-metals
summary: |
  Zirconium is the element Zr, sold as commercially pure Zr 702, niobium-alloyed Zr 705, and as Zircaloy-4 for nuclear fuel cladding. Zr 702 (UNS R60702) has a density of 6.51 g/cm3, a melting point of 1852 °C and a thermal conductivity of 22 W/(m·K) at 300 to 800 K. Its typical room-temperature yield strength is 321.1 MPa, and it falls to 97.2 MPa at 316 °C. The metal resists hot nitric acid very well, with a corrosion rate of 0.0 mpy in 65 % nitric acid at 204 °C. Dry zirconium powder can ignite spontaneously, and the strength falls fast when hot.
best_for: 'Corrosion resistance in acids, especially hot nitric acid: 0.0 mpy for Zr 702 in 65 % nitric acid at 204 °C (ATI nitric acid sheet, Table 1)'
weakest_at: Dry powder fire risk, delayed hydride cracking of Zircaloy cladding, and loss of strength when hot (Zr 702 yield 97.2 MPa at 316 °C)
identity:
  formula: 'Zr (element, atomic number 40); commercial grades: Zr 702 (Zr plus Hf 99.2 % min, Hf 4.5 % max, O 0.16 % max), Zr 705 (Zr plus Hf 95.5 % min, Nb 2.0 to 3.0 %, O 0.18 % max), Zircaloy-4 (Sn 1.20 to 1.70, Fe 0.18 to 0.24, Cr 0.07 to 0.13 wt %; nominal Zr-1.5Sn-0.2Fe-0.1Cr)'
  cas: 7440-67-7
  source: pubchem-zr
  where: 'Names and Identifiers > Other Identifiers > CAS (PubChem compound CID 23995, zirconium element). Grade compositions: ATI Zircadyne Table 1 (Zr 702 and Zr 705) and the ATI zirconium alloys composition table (Zircaloy-4).'
  designations:
    - system: UNS
      code: R60702
      source: ati-702-705
      where: Table 1, row UNS Designation, Zr 702 column
    - system: UNS
      code: R60705
      source: ati-702-705
      where: Table 1, row UNS Designation, Zr 705 column
    - system: UNS
      code: R60804
      source: ati-nuclear-zircaloy
      where: Zirconium alloys text, Zircaloy-4 (Grade R60804); composition table, UNS Grade column
    - system: ASME
      code: SB 551
      note: plate, sheet and strip, grades 702 and 705
      source: ati-702-705
      where: Table 6A, row Plate, Sheet, Strip, specification SB 551
    - system: Trade name
      code: Zircadyne 702
      source: ati-702-705
      where: Title block and Table 1 heading
    - system: Trade name
      code: Zircadyne 705
      source: ati-702-705
      where: Title block and Table 1 heading
    - system: Trade name
      code: Zircaloy-4
      source: ati-nuclear-zircaloy
      where: Zirconium alloys text, Zircaloy-4 paragraph
tags:
  environments: []
  stresses:
    - corrosion
  applications:
    - structures
    - thermal-control
properties:
  - benchmark: density
    label: Density, Zr 702
    value: 6.51
    unit: g/cm3
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temperature: not stated
      unit_in_source: 6.51 (0.235) g/cm3 (lbs/in3)
      product: 'annealed mill product (ATI: mill products are supplied annealed unless specified otherwise)'
    method: Typical value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 4, Physical Properties, row Density, column Zr 702
  - benchmark: density
    label: Density, Zr 705
    value: 6.64
    unit: g/cm3
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temperature: not stated
      unit_in_source: 6.64 (0.240) g/cm3 (lbs/in3)
      product: annealed mill product
    method: Typical value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 4, Physical Properties, row Density, column Zr 705
  - benchmark: density
    label: Density, Zircaloy-4
    value: 6.55
    unit: g/cc
    scope: material
    conditions:
      grade: Zircaloy-4 (UNS R60804)
      temperature: not stated
      unit_in_source: 6.55 g/cc (0.237 lbs/cu.-in.)
    method: Value printed in ATI reactor-grade zirconium data sheet, Properties of Zircaloy-4 table
    status: ground
    source: ati-nuclear-zircaloy
    where: Properties of Zircaloy-4 table, row Density
  - benchmark: density
    label: Density, zirconium metal (element record)
    value: 6.51
    unit: g/cm3
    scope: material
    conditions:
      form: metal (element)
      temperature: not stated
      unit_in_source: 6.51 (Metal), printed without unit in the record as 6.51 (Metal) (NIOSH, 2024)
    method: Value listed under Density in the PubChem experimental properties, attributed to NIOSH (2024)
    status: ground
    source: pubchem-zr
    where: Chemical and Physical Properties > Experimental Properties > Density, entry 6.51 (Metal) (NIOSH, 2024)
  - benchmark: melting_point
    label: Melting point, Zr 702
    value: 1852
    unit: °C
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      pressure: not stated
    method: Value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 2, Thermal Properties, row Melting Point, column Zr 702
  - benchmark: melting_point
    label: Melting point, Zr 705
    value: 1840
    unit: °C
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      pressure: not stated
    method: Value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 2, Thermal Properties, row Melting Point, column Zr 705
  - benchmark: melting_point
    label: Melting point, Zircaloy-4
    value: 1850
    unit: °C
    scope: material
    conditions:
      grade: Zircaloy-4 (UNS R60804)
      unit_in_source: 1850 °C (3,362 °F)
    method: Value printed in ATI reactor-grade zirconium data sheet
    status: ground
    source: ati-nuclear-zircaloy
    where: Properties of Zircaloy-4 table, row Melting Point
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Zr 702
    value: 22
    unit: W/(m·K)
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temperature: 300 to 800 K
      unit_in_source: 22 (13) w/m-°K (BTU/hr-ft-°F)
    method: Value printed in ATI Zircadyne technical data sheet, averaged over the stated temperature range
    status: ground
    source: ati-702-705
    where: Table 2, Thermal Properties, row Thermal Conductivity 300-800K, column Zr 702
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Zr 705
    value: 17.1
    unit: W/(m·K)
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temperature: 300 to 800 K
      unit_in_source: 17.1 (10) w/m-°K (BTU/hr-ft-°F)
    method: Value printed in ATI Zircadyne technical data sheet, averaged over the stated temperature range
    status: ground
    note: The same table gives 22 W/(m·K) for Zr 702 over this range, so the 705 grade conducts less heat.
    source: ati-702-705
    where: Table 2, Thermal Properties, row Thermal Conductivity 300-800K, column Zr 705
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Zircaloy-4
    value: 21.5
    unit: W/(m·K)
    scope: material
    conditions:
      grade: Zircaloy-4 (UNS R60804)
      temperature: not stated
      unit_in_source: 21.5 Watts/m-K (149 BTU-in/hr-ft2-°F)
    method: Value printed in ATI reactor-grade zirconium data sheet, Properties of Zircaloy-4 table
    status: ground
    source: ati-nuclear-zircaloy
    where: Properties of Zircaloy-4 table, row Thermal Conductivity
  - benchmark: specific_heat
    label: Specific heat, Zr 702
    value: 0.2847
    unit: kJ/(kg·K)
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temperature: 0 to 100 °C
      unit_in_source: 0.2847 KJ/kg-K (0-100°C)
    method: Value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 2, Thermal Properties, row Specific Heat (0-100°C), column Zr 702
  - benchmark: specific_heat
    label: Specific heat, Zircaloy-4
    value: 0.285
    unit: J/(g·°C)
    scope: material
    conditions:
      grade: Zircaloy-4 (UNS R60804)
      temperature: not stated
    method: Value printed in ATI reactor-grade zirconium data sheet, Properties of Zircaloy-4 table
    status: ground
    source: ati-nuclear-zircaloy
    where: Properties of Zircaloy-4 table, row Heat Capacity
  - benchmark: cte
    label: Coefficient of thermal expansion, Zr 702 at 149 °C
    value: 6.3
    unit: 10-6/°C
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temperature: 149 °C (300 °F)
      unit_in_source: 6.3 (3.5) x 10-6/°C
    method: Value printed in ATI Zircadyne technical data sheet; the first CTE row has no temperature label, so only the labelled 149 °C row is used
    status: ground
    source: ati-702-705
    where: Table 2, Thermal Properties, row Coefficient of Thermal Expansion, 149°C (300°F) row, column Zr 702
  - benchmark: cte
    label: Coefficient of thermal expansion, Zr 705 at 149 °C
    value: 4.9
    unit: 10-6/°C
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temperature: 149 °C (300 °F)
      unit_in_source: 4.9 (2.7) x 10-6/°C
    method: Value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 2, Thermal Properties, row Coefficient of Thermal Expansion, 149°C (300°F) row, column Zr 705
  - benchmark: cte
    label: Coefficient of thermal expansion, Zircaloy-4 at 25 °C
    value: 6
    unit: µm/(m·°C)
    scope: material
    conditions:
      grade: Zircaloy-4 (UNS R60804)
      temperature: 25 °C
      unit_in_source: 6 µm/m °C (3.3 µin/in-°F)
    method: Value printed in ATI reactor-grade zirconium data sheet, Properties of Zircaloy-4 table
    status: ground
    source: ati-nuclear-zircaloy
    where: Properties of Zircaloy-4 table, row Coefficient of Thermal Expansion at 25ºC
  - benchmark: elastic_modulus
    label: Modulus of elasticity, Zr 702 at room temperature
    value: 99.2
    unit: GPa
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temperature: room temperature
      unit_in_source: 99.2 (14.4) GPa (psi x 10^6)
    method: Value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 4, Physical Properties, Modulus of Elasticity, Room Temperature row, column Zr 702
  - benchmark: elastic_modulus
    label: Modulus of elasticity, Zr 705 at room temperature
    value: 94.7
    unit: GPa
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temperature: room temperature
      unit_in_source: 94.7 (13.7) GPa (psi x 10^6)
    method: Value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 4, Physical Properties, Modulus of Elasticity, Room Temperature row, column Zr 705
  - benchmark: elastic_modulus
    label: Modulus of elasticity, Zircaloy-4
    value: 99.3
    unit: GPa
    scope: material
    conditions:
      grade: Zircaloy-4 (UNS R60804)
      temperature: not stated
      unit_in_source: 99.3 Gpa (14,402 ksi)
    method: Value printed in ATI reactor-grade zirconium data sheet, Properties of Zircaloy-4 table
    status: ground
    source: ati-nuclear-zircaloy
    where: Properties of Zircaloy-4 table, row Modulus of Elasticity
  - benchmark: shear_modulus
    label: Shear modulus, Zr 702 at room temperature
    value: 36.2
    unit: GPa
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temperature: room temperature
      unit_in_source: 36.2 (5.25) GPa (psi x 10^6)
    method: Value printed in ATI Zircadyne technical data sheet
    status: ground
    source: ati-702-705
    where: Table 4, Physical Properties, Shear Modulus of Elasticity, Room Temperature row, column Zr 702
  - benchmark: yield_strength
    label: Yield strength, Zr 702, typical at room temperature
    value: 321.1
    unit: MPa
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temper: 'annealed (ATI: data are for the annealed condition)'
      temperature: room temperature
      measure: 0.2 % offset
      unit_in_source: 321.1 MPa (46.6 ksi)
      direction: average of longitudinal and transverse values
    method: Typical value printed in ATI Zircadyne technical data sheet, Table 5 heading, Cold Worked and Annealed block
    status: ground
    note: The ASTM minimum for the same grade is 207 MPa, and the typical value is shown in the same table.
    source: ati-702-705
    where: Table 5, Zircadyne 702 (R60702) block, row Yield Strength, Room Temp. column
  - benchmark: yield_strength
    label: Yield strength, Zr 702, ASTM minimum
    value: 207
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temper: annealed
      unit_in_source: 207 MPa (30 ksi)
      basis: ASTM minimum value
    method: Minimum value printed in ATI Zircadyne technical data sheet, Table 5 ASTM Min Value column
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 702 (R60702) block, row Yield Strength, ASTM Min Value column
  - benchmark: yield_strength
    label: Yield strength, Zr 705, typical at room temperature
    value: 506.1
    unit: MPa
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temper: annealed
      temperature: room temperature
      measure: 0.2 % offset
      unit_in_source: 506.1 MPa (73.4 ksi)
    method: Typical value printed in ATI Zircadyne technical data sheet, Table 5
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 705 (R60705) block, row Yield Strength, Room Temp. column
  - benchmark: yield_strength
    label: Yield strength, Zr 705, ASTM minimum
    value: 379
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temper: annealed
      unit_in_source: 379.0 MPa (55 ksi)
      basis: ASTM minimum value
    method: Minimum value printed in ATI Zircadyne technical data sheet, Table 5 ASTM Min Value column
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 705 (R60705) block, row Yield Strength, ASTM Min Value column
  - benchmark: yield_strength
    label: Yield strength, Zr 702, typical at 316 °C
    value: 97.2
    unit: MPa
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temper: annealed
      temperature: 316 °C (600 °F)
      measure: 0.2 % offset
      unit_in_source: 97.2 MPa (14.1 ksi)
    method: Typical value printed in ATI Zircadyne technical data sheet, Table 5
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 702 (R60702) block, row Yield Strength, 316°C (600°F) column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Zr 702, typical at room temperature
    value: 468.1
    unit: MPa
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temper: annealed
      temperature: room temperature
      unit_in_source: 468.1 MPa (67.9 ksi)
    method: Typical value printed in ATI Zircadyne technical data sheet, Table 5
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 702 (R60702) block, row Ultimate Tensile Strength, Room Temp. column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Zr 702, ASTM minimum
    value: 379
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temper: annealed
      unit_in_source: 379 MPa (55 ksi)
      basis: ASTM minimum value
    method: Minimum value printed in ATI Zircadyne technical data sheet, Table 5 ASTM Min Value column
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 702 (R60702) block, row Ultimate Tensile Strength, ASTM Min Value column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Zr 705, typical at room temperature
    value: 615
    unit: MPa
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temper: annealed
      temperature: room temperature
      unit_in_source: 615.0 MPa (89.2 ksi)
    method: Typical value printed in ATI Zircadyne technical data sheet, Table 5
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 705 (R60705) block, row Ultimate Tensile Strength, Room Temp. column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Zr 705, ASTM minimum
    value: 552
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temper: annealed
      unit_in_source: 552.0 MPa (80 ksi)
      basis: ASTM minimum value
    method: Minimum value printed in ATI Zircadyne technical data sheet, Table 5 ASTM Min Value column
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 705 (R60705) block, row Ultimate Tensile Strength, ASTM Min Value column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Zircaloy-4, annealed 2 mm strip, longitudinal, room temperature
    value: 541
    unit: MPa
    scope: material
    conditions:
      grade: Zircaloy-4 (UNS R60804)
      temper: annealed 2 mm thick strip
      orientation: longitudinal
      temperature: room temperature
      unit_in_source: 541 MPa (78.4 ksi)
    method: Value printed in ATI reactor-grade zirconium data sheet, Mechanical properties of Zircaloy-4 annealed 2 mm thick strip table
    status: ground
    source: ati-nuclear-zircaloy
    where: Mechanical properties of Zircaloy-4 annealed 2 mm thick strip table, row Ultimate Tensile Strength, Longitudinal Room Temp column
  - benchmark: elongation
    label: Elongation, Zr 702, typical at room temperature
    value: 28.9
    unit: '%'
    scope: material
    conditions:
      grade: Zr 702 (UNS R60702)
      temper: annealed
      temperature: room temperature
      basis: as printed as 0.2 % offset row label
    method: Typical value printed in ATI Zircadyne technical data sheet, Table 5 (the printed row label reads Elongation, % (0.2% offset))
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 702 (R60702) block, row Elongation, Room Temp. column
  - benchmark: elongation
    label: Elongation, Zr 705, typical at room temperature
    value: 18.8
    unit: '%'
    scope: material
    conditions:
      grade: Zr 705 (UNS R60705)
      temper: annealed
      temperature: room temperature
    method: Typical value printed in ATI Zircadyne technical data sheet, Table 5
    status: ground
    source: ati-702-705
    where: Table 5, Zircadyne 705 (R60705) block, row Elongation, Room Temp. column
  - benchmark: thermal_neutron_cross_section
    label: Thermal neutron cross section, zirconium
    value: 0.18
    unit: barns
    scope: material
    conditions:
      form: zirconium element
      neutron: thermal
      unit_in_source: 0.18 barns
    method: Value printed in ATI reactor-grade zirconium data sheet, Thermal neutron cross sections table
    status: ground
    source: ati-nuclear-zircaloy
    where: Thermal neutron cross sections (barns) table, row Zirconium
  - benchmark: thermal_neutron_cross_section
    label: Thermal neutron cross section, Zircaloy-4
    value: 0.22
    unit: barns
    scope: material
    conditions:
      grade: Zircaloy-4 (UNS R60804)
      neutron: thermal
      unit_in_source: 0.22 barns
    method: Value printed in ATI reactor-grade zirconium data sheet, Thermal neutron cross sections table
    status: ground
    source: ati-nuclear-zircaloy
    where: Thermal neutron cross sections (barns) table, row Zircaloy-4
corrosion:
  - environment: Hydrochloric acid, 10 %, 30 °C
    headline: Dilute hot-ish hydrochloric acid is mild to zirconium, but stress corrosion cracking was seen.
    effect: Both grades corrode at under 1 mpy in 10 % HCl at 30 °C, but the table remark reads SCC observed. Stress corrosion cracking can occur even when the uniform rate is low.
    rating: moderate
    conditions:
      medium: hydrochloric acid, 10 %
      temperature: 30 °C
      unit_in_source: mpy
    source: ati-corrosion-tables
    where: Table 6, row Hydrochloric Acid 10 %, 30 °C, remarks column SCC observed
  - environment: Ferric chloride, 0 to 50 %, room temperature to 100 °C
    headline: Ferric chloride attacks both zirconium grades at more than 50 mpy.
    effect: The table shows a corrosion rate above 50 mpy for Zr 702 and Zr 705 over the whole printed range.
    rating: severe
    conditions:
      medium: ferric chloride, 0 to 50 %
      temperature: room temperature to 100 °C
      unit_in_source: mpy
    source: ati-corrosion-tables
    where: Table 5, row Ferric Chloride, columns Zr 702 and Zr 705
  - environment: Cupric chloride, 5 to 20 %, 35 to 100 °C
    headline: Cupric chloride is another strong attacker of zirconium.
    effect: Both grades show above 50 mpy in cupric chloride at 5, 10 and 20 % from 35 to 100 °C.
    rating: severe
    conditions:
      medium: cupric chloride, 5, 10 and 20 %
      temperature: 35 to 100 °C
      unit_in_source: mpy
    source: ati-corrosion-tables
    where: Table 5, row Cupric Chloride, columns Zr 702 and Zr 705
  - environment: Hydrofluoric acid, all concentrations, room temperature
    headline: Hydrofluoric acid is the clearest case where zirconium is not protected.
    effect: Zr 702 corrodes at more than 50 mpy in hydrofluoric acid at all concentrations at room temperature. No Zr 705 value is printed.
    rating: severe
    conditions:
      medium: hydrofluoric acid, all concentrations
      temperature: room temperature
      unit_in_source: mpy
    source: ati-corrosion-tables
    where: Table 8, row Hydrofluoric Acid, Zr 702 column
  - environment: Nitric acid, 20 %, 103 °C
    headline: Zirconium is nearly immune to nitric acid at this strength.
    effect: Both grades corrode at under 1 mpy in 20 % nitric acid at 103 °C.
    rating: low
    conditions:
      medium: nitric acid, 20 %
      temperature: 103 °C
      unit_in_source: mpy
    source: ati-corrosion-tables
    where: Table 9, row Nitric Acid 20 %, 103 °C, columns Zr 702 and Zr 705
  - environment: Nitric acid, 65 %, 121 to 204 °C
    headline: Zr 702 shows no measured attack in boiling 65 % nitric acid up to 204 °C, while stainless steel 310 corrodes fast.
    effect: ATI prints 0.0 mpy for Zr 702 and for welded Zr 702 at 121, 149 and 204 °C. The same table gives 1064 mpy for stainless steel 310 at 204 °C and 86 mpy at 149 °C.
    rating: none
    conditions:
      medium: nitric acid, 65 %
      temperature: 121, 149 and 204 °C
      unit_in_source: mpy (mm/yr)
    source: ati-nitric-acid
    where: Table 1, Corrosion of Zircadyne 702 vs. other alloys in 65% Nitric Acid, rows Zircadyne 702 and Stainless Steel 310
  - environment: Sulfuric acid, 70 %, 150 °C (Zircaloy-4)
    headline: Zircaloy-4 stays under 0.13 mm/a in hot sulfuric acid.
    effect: The ATI corrosion table prints under 0.13 mm/a (under 5 mpy) for Zircaloy-4 in 70 % sulfuric acid at 150 °C.
    rating: low
    conditions:
      medium: sulfuric acid, 70 %
      temperature: 150 °C
      unit_in_source: mm/a (mpy)
    source: ati-nuclear-zircaloy
    where: Corrosion rate data for Zircaloy-4 table, row H2 SO4, 70 %, 150 °C
  - environment: Hydrochloric acid, 70 %, 160 °C (Zircaloy-4)
    headline: Strong hot hydrochloric acid attacks Zircaloy-4 at a measurable rate.
    effect: The Zircaloy-4 corrosion table prints 0.36 mm/a (14 mpy) in 70 % HCl at 160 °C.
    rating: moderate
    conditions:
      medium: hydrochloric acid, 70 %
      temperature: 160 °C
      unit_in_source: mm/a (MPY)
    source: ati-nuclear-zircaloy
    where: Corrosion rate data for Zircaloy-4 table, row HCl, 70 %, 160 °C
risks:
  hazards:
    - text: Dry zirconium powder can catch fire spontaneously in air. PubChem's ECHA C&L aggregate (422 company reports, 14 notifications) gives H250 catches fire spontaneously if exposed to air (43.8 %), H251 self-heating, may catch fire (42.2 %), and H260 in contact with water releases flammable gases (43.6 %). Signal word Danger. The record notes that the class depends on form and impurities.
      ghs:
        - H250
        - H251
        - H260
      source: pubchem-zr
      where: Safety and Hazards > GHS Classification, ECHA C&L Notifications Summary
    - text: The main hazard in powder form is flammability, while the solid form is much less prone to ignition, according to Wikipedia. Wetted powder with at least 25 % water is a regulated shipping item, UN 1358.
      ghs: []
      source: wikipedia-zr
      where: Lead and Characteristics sections; PubChem Transport Information row UN 1358
    - text: Mechanical irritation of the eyes from the metal, and OSHA permissible exposure limit of 5 mg/m3 over an 8-hour day for zirconium, per Wikipedia's safety section.
      ghs: []
      source: wikipedia-zr
      where: Safety section; PubChem Skin, Eye and Respiratory Irritations row
  failure_risks:
    - mode: Delayed hydride cracking of Zircaloy cladding
      trigger: Hydrogen uptake and stress raisers such as notches and cracks, during reactor cycles or spent-fuel storage of high-burnup fuel rods
      consequence: Hydride precipitation makes Zircaloy susceptible to embrittlement, and delayed hydride cracking threatens the safety and structural integrity of fuel cladding. The paper gives no rate.
      severity: high
      source: arxiv-zircaloy4
      where: Section 1, Introduction, paragraph 1
    - mode: Stress corrosion cracking in dilute hydrochloric acid
      trigger: 10 % HCl at 30 °C, where the table remark reads SCC observed
      consequence: Cracking can occur even when the uniform corrosion rate is under 1 mpy for both grades.
      severity: moderate
      source: ati-corrosion-tables
      where: Table 6, row Hydrochloric Acid 10 %, 30 °C, remarks column
    - mode: Rapid corrosion in ferric and cupric chlorides
      trigger: Ferric chloride 0 to 50 % at room temperature to 100 °C, or cupric chloride 5 to 20 % at 35 to 100 °C
      consequence: Corrosion rates above 50 mpy for both grades in the printed tables.
      severity: high
      source: ati-corrosion-tables
      where: Table 5, rows Ferric Chloride and Cupric Chloride
    - mode: Strength loss when hot
      trigger: Zr 702 held at 316 °C
      consequence: Typical yield strength falls from 321.1 MPa at room temperature to 97.2 MPa at 316 °C.
      severity: moderate
      source: ati-702-705
      where: Table 5, Zircadyne 702 (R60702) block, row Yield Strength
    - mode: Welded Zr 705 left unrelieved
      trigger: Welding Zr 705 parts without a stress relief
      consequence: The sheet says Zr 705 requires a stress relief heat treatment within 14 days after welding. It does not print the failure outcome if this is skipped.
      severity: moderate
      source: ati-702-705
      where: Mechanical properties text, ASME allowable stress paragraph
  side_effects:
    - text: 'Hafnium traces: reactor-grade zirconium limits hafnium to 0.010 % maximum, because hafnium has a thermal neutron cross section of 104 barns against 0.18 barns for zirconium.'
      affects: Neutron economy in reactor cores
      source: ati-nuclear-zircaloy
      where: Zirconium alloys text, Reactor grade paragraph; Thermal neutron cross sections table
  handling:
    - text: 'Stress relieve after fabrication: ATI gives 565 °C (1050 °F plus or minus 50 °F) for 1/2 to 1 hour to relieve residual stresses.'
      source: ati-702-705
      where: Mechanical properties text, stress relief paragraph
    - text: 'Keep dry powder away from air and moisture: the PubChem record says dry powder may ignite spontaneously and burn with explosive violence.'
      source: pubchem-zr
      where: Physical Description, Zirconium powder, dry
    - text: 'Expect rapid work hardening: ATI says Zircadyne alloys work harden rapidly.'
      source: ati-702-705
      where: Mechanical properties text, paragraph after Table 5
  mitigations: []
uses:
  - application: structures
    device: ASME pressure vessels and process equipment
    example: ATI states that both Zircadyne alloys are approved for pressure vessels under the ASME Boiler and Pressure Vessel Code, and prints allowable stress tables for plate, sheet, strip, tube and forgings (SB 551 and related specifications).
    source: ati-702-705
    where: ASME allowable stress text and Tables 6A and 6B
  - application: thermal-control
    device: Heat exchangers and condensers
    example: ATI says Zircadyne alloys have a thermal conductivity more than 30 % higher than stainless steel alloys, which makes them suited to heat exchangers. A nitric acid sheet calls zirconium the preferred material for cooler condensers at 204 °C in monopressure nitric acid plants.
    source: ati-702-705
    where: Thermal properties text, paragraph before Table 2; see also ati-nitric-acid introduction
  - application: structures
    device: Nuclear fuel cladding
    example: Zircaloy-4 is typically used as fuel cladding in pressurized water reactors and CANDU reactors. Nuclear fuel cladding takes about 1 % of the world zirconium supply, per Wikipedia.
    source: ati-nuclear-zircaloy
    where: Zirconium alloys introduction, Zircaloy-4 paragraph
  - application: structures
    device: Chemical plant equipment in nitric acid service
    example: In 65 % nitric acid at 204 °C, Zr 702 shows 0.0 mpy against 1064 mpy for stainless steel 310, so zirconium is used for nitric acid process equipment.
    source: ati-nitric-acid
    where: Table 1, Corrosion of Zircadyne 702 vs. other alloys in 65% Nitric Acid
supply:
  - subject: Zirconium mineral concentrates (zircon), 2025 mine production
    producers:
      - country: Australia
        share_percent: 33.3
        year: 2025
      - country: South Africa
        share_percent: 22.5
        year: 2025
      - country: Mozambique
        share_percent: 13.3
        year: 2025
      - country: China
        share_percent: 8.3
        year: 2025
      - country: United States
        share_percent: 8.3
        year: 2025
    critical_lists: []
    recycling: Companies in Oregon and Utah recycle zirconium from new scrap generated in metal production and fabrication, and from old scrap. Zircon foundry mold cores and spent zirconia refractories are often recycled but cannot be quantified. Hafnium metal recycling is minimal.
    substitutes:
      - 'USGS: chromite and olivine can substitute for zircon in some foundry uses; dolomite and spinel refractories in some high-temperature uses; niobium, stainless steel and tantalum in some nuclear uses; boron or cadmium-silver-indium alloys for hafnium in control rods.'
    source: usgs-mcs2026-zirconium
    where: 'World Mine Production and Reserves table, zirconium mineral concentrates, 2025 column: Australia 400, South Africa 270, Mozambique 160, China 100, United States 100, world total 1,200 thousand t gross weight (rounded). Shares are calculated by Space Mushroom as country value divided by the printed world total. Substitutes and Recycling sections.'
  - subject: Zirconium reserves, ZrO2 content, 2025
    producers:
      - country: Australia
        year: 2025
      - country: South Africa
        year: 2025
    critical_lists: []
    recycling: No recycling figure is printed in the USGS summary.
    substitutes: []
    source: usgs-mcs2026-zirconium
    where: 'World Mine Production and Reserves table, Zirconium reserves column: Australia 55,000 and South Africa 5,900 thousand t ZrO2 content; world more than 70,000 thousand t.'
  - subject: Unwrought zirconium and powder, import sources 2021 to 2024
    producers:
      - country: China
        share_percent: 55
        year: 2024
      - country: Germany
        share_percent: 15
        year: 2024
      - country: Canada
        share_percent: 12
        year: 2024
      - country: France
        share_percent: 7
        year: 2024
    critical_lists: []
    recycling: See the zirconium mineral supply entry above; the USGS summary does not quantify scrap recycling of zirconium metal.
    substitutes: []
    source: usgs-mcs2026-zirconium
    where: 'Import Sources (2021-24), Zirconium unwrought: China 55 %, Germany 15 %, Canada 12 %, France 7 %, other 11 %. The year in this entry is the end of the 2021 to 2024 window.'
documents:
  - title: ATI Zircadyne 702 and 705 technical data sheet (UNS R60702 and R60705), version 1, 2012
    type: datasheet
    url: https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/zircadyne_702_705_1_v1.pdf
    year: 2012
  - title: ATI Zirconium Alloys technical data sheet, reactor grade zirconium (Zircaloy-2, Zircaloy-4, Zr-2.5Nb), version 1, 2015
    type: datasheet
    url: https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/Zr_nuke_waste_disposal_v1.pdf
    year: 2015
  - title: ATI Zircadyne Zirconium Corrosion Data technical data sheet, version 1, 2011
    type: datasheet
    url: https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/zirconium-corrosion-data-tables.pdf
    year: 2011
  - title: ATI Zircadyne 702/705 in Nitric Acid technical data sheet, version 1, 2014
    type: datasheet
    url: https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/zircadyne_702_705_in_nitric_acid_v1.pdf
    year: 2014
  - title: 'USGS Mineral Commodity Summaries 2026: Zirconium and Hafnium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zirconium-hafnium.pdf
    year: 2026
  - title: 'Wikipedia: Zirconium (characteristics, Kroll process, nuclear applications, safety)'
    type: database
    url: https://en.wikipedia.org/wiki/Zirconium
    year: 2026
  - title: PubChem compound record for zirconium (CID 23995), including ECHA C&L classification, NIOSH density and melting point, DOT shipping information
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Zirconium
    year: 2026
  - title: Liu et al., Characterisation of microstructural creep, strain rate and temperature sensitivity and computational crystal plasticity in Zircaloy-4, arXiv:2109.05333
    type: paper
    url: https://arxiv.org/pdf/2109.05333
    year: 2021
gaps:
  - The EN material numbers for Zr 702 and Zr 705 (3.7025 and 3.7035 from memory) were not printed in any page read in this run, so they are left out. EN, DIN and JIS designations are not listed.
  - The Rolled Alloys zirconium datasheet was not reachable (HTTP 404 on the URL tried, and no Rolled Alloys page came up in search), so its figures are not used.
  - The USGS 2026 summary read here does not state whether zirconium is on the U.S. critical minerals list, so critical_lists is empty.
  - Electrical resistivity and electrical conductivity of zirconium grades were not found in any page read in this run.
  - Hydrogen embrittlement limits and the claimed better hydrogen resistance of Zr 705 were not found in a fetched source; only search snippets mentioned them.
  - 'Zircaloy-4 yield strength: the same ATI table prints 80 MPa for the longitudinal direction and 468 MPa for the transverse direction at room temperature. The 80 MPa value looks anomalous and is not used; only the ultimate tensile strength is recorded.'
  - The arXiv paper (Liu et al.) gives room-temperature and 623 K yield values only from a crystal-plasticity model fit (Table 2), so none of them are recorded as property values.
  - Thermal neutron cross section is recorded under the non-canonical name thermal_neutron_cross_section, because no canonical name exists for it in spores/property-canon.yaml.
  - Outgassing, total mass loss, cold welding and atomic oxygen erosion for zirconium were not searched in a fetched source.
  - Radiation damage (displacement and total dose) for zirconium alloys was not looked up.
  - Crustal abundance of zirconium and its share in lunar or Martian regolith were not looked up.
  - The melting point differs by a few degrees between sources (Wikipedia 1852 and 1855 °C; PubChem 1854 and 1857 °C; ATI 1852 °C). Only the ATI grade values are recorded.
  - PubChem lists the element density as 6.51 g/cm3 (NIOSH) but also gives 6.52 g/cm3 at 25 °C; only the NIOSH entry is recorded.
sources:
  ati-702-705:
    title: Zircadyne 702 and 705 Zirconium Alloys (UNS R60702 and UNS R60705), ATI Technical Data Sheet, version 1, 2012
    id: UNS R60702, UNS R60705; ASME SB 551 (plate, sheet, strip), SB 523 (tubing), SB 493 (forgings), SB 550 (bar), SB 658 (pipe)
    url: https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/zircadyne_702_705_1_v1.pdf
    year: 2012
    kind: datasheet
    license: Manufacturer datasheet, typical data, not for specification (cited, not reproduced)
  ati-nuclear-zircaloy:
    title: 'Zirconium Alloys: Reactor Grade Zirconium, ATI Technical Data Sheet, version 1, 2015'
    id: UNS R60802 (Zircaloy-2), R60804 (Zircaloy-4), R60904 (Zr-2.5Nb)
    url: https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/Zr_nuke_waste_disposal_v1.pdf
    year: 2015
    kind: datasheet
    license: Manufacturer datasheet, typical data (cited, not reproduced)
  ati-corrosion-tables:
    title: Zircadyne Zirconium Corrosion Data, ATI Technical Data Sheet, version 1, 2011
    url: https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/zirconium-corrosion-data-tables.pdf
    year: 2011
    kind: datasheet
    license: Manufacturer datasheet, typical data (cited, not reproduced)
  ati-nitric-acid:
    title: Zircadyne 702/705 in Nitric Acid, ATI Technical Data Sheet, version 1, 2014
    id: UNS R60702
    url: https://www.atimaterials.com/Products/Documents/datasheets/zirconium/alloy/zircadyne_702_705_in_nitric_acid_v1.pdf
    year: 2014
    kind: datasheet
    license: Manufacturer datasheet, typical data (cited, not reproduced)
  usgs-mcs2026-zirconium:
    title: 'Mineral Commodity Summaries 2026: Zirconium and Hafnium (Shelby N. Johnston, U.S. Geological Survey)'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zirconium-hafnium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  wikipedia-zr:
    title: Zirconium, Wikipedia (characteristics, production, nuclear applications, safety)
    url: https://en.wikipedia.org/wiki/Zirconium
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  pubchem-zr:
    title: 'PubChem compound record: Zirconium (CID 23995), including ECHA C&L Inventory classification and NIOSH and DOE property entries'
    id: CAS 7440-67-7
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23995/JSON/
    year: 2026
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA, NIOSH and others
  arxiv-zircaloy4:
    title: Characterisation of microstructural creep, strain rate and temperature sensitivity and computational crystal plasticity in Zircaloy-4 (Liu, Wan, El Chamaa, Wenman, Davies, Dunne), arXiv:2109.05333
    id: arXiv:2109.05333
    url: https://arxiv.org/pdf/2109.05333
    year: 2021
    kind: paper
    license: arXiv preprint (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-25'
review:
  status: draft
  method: assistant
  checked_values: 33
  unreachable: 1
  caveats: 6
  note: 'Values were read by an AI assistant on 2026-10-25 from the pages and PDFs named in each entry (ATI PDFs and PubChem and USGS text extracted from the documents). Unreachable: Rolled Alloys datasheet (404). Caveats: all strength and thermal values are typical or minimum values from manufacturer datasheets, not ASTM or NRC specification values; the Zircaloy-4 yield value is not used because the printed longitudinal value looks anomalous; the element density and melting point are from the PubChem record and differ slightly between sources; supply shares for zircon mine production are calculated from the printed world total; no EN or DIN designation was verified.'
story:
  risk_groups:
    - title: For people
      lead: The main human hazard is dry powder, which can burn. Solid metal is much less prone to ignition.
      level: 1
      verdict: Powder is the hazard
      points:
        - label: Dry powder
          line: PubChem's ECHA aggregate gives H250, catches fire spontaneously if exposed to air (43.8 %), and H260, releases flammable gases in water (43.6 %). The record says dry powder may ignite spontaneously and burn with explosive violence.
        - label: Solid metal
          line: Wikipedia says the solid form is much less prone to ignition. Eye irritation is the main effect of short exposure, and the OSHA limit for zirconium is 5 mg/m3 over 8 hours.
    - title: If it fails
      lead: These are failure routes in the sources. The reactor cladding route is a published failure mode, the chloride routes are printed table results.
      points:
        - label: Hydride cracking in cladding
          line: A Zircaloy-4 paper says hydrides embrittle the alloy and delayed hydride cracking threatens the integrity of fuel cladding, especially near notches and cracks.
        - label: Chlorides and HF
          line: Ferric and cupric chlorides run above 50 mpy for both grades, and hydrofluoric acid runs above 50 mpy for Zr 702. Dilute HCl at 30 °C shows SCC in the table remark.
        - label: Hot strength
          line: Zr 702 yield falls from 321.1 MPa at room temperature to 97.2 MPa at 316 °C in the typical data.
    - title: Handling and storage
      points:
        - label: Stress relief
          line: Relieve residual stress at 565 °C for 1/2 to 1 hour, and do it within 14 days after welding Zr 705.
        - label: Powder
          line: Keep powder wetted with at least 25 % water, the shipping form UN 1358, and do not let dry powder sit in air.
  why: Zirconium resists corrosion very well, and its thermal neutron cross section is low (0.18 barns for the element, 0.22 barns for Zircaloy-4). Zr 702 is commercially pure, while Zr 705 adds 2.0 to 3.0 % niobium for strength, and Zircaloy-4 adds tin, iron and chromium for nuclear cladding. Zr 702 has a density of 6.51 g/cm3 and a melting point of 1852 °C. Its thermal conductivity is 22 W/(m·K) at 300 to 800 K. In hot nitric acid it shows no measured attack, at 0.0 mpy at 204 °C.
  uses:
    - where: Pressure vessels
      line: ATI says both Zircadyne alloys are approved for ASME pressure vessels, and prints allowable stress tables for plate, sheet, strip and forgings under SB 551 and related specifications.
    - where: Heat exchangers
      line: ATI says Zircadyne alloys conduct heat more than 30 % better than stainless steel alloys, which suits heat exchangers and condensers.
    - where: Nuclear fuel cladding
      line: Zircaloy-4 is the usual fuel cladding in pressurized water reactors, and cladding takes about 1 % of the zirconium supply.
  can_do:
    - label: Resist acid
      value: 0.0 mpy
      line: Zr 702 shows 0.0 mpy in 65 % nitric acid at 121, 149 and 204 °C in the ATI table, against 1064 mpy for stainless steel 310 at 204 °C.
    - label: Carry heat
      value: 22 W/(m·K)
      benchmark: thermal_conductivity
      line: Zr 702 conducts at 22 W/(m·K) over 300 to 800 K, and Zr 705 at 17.1 W/(m·K).
    - label: Weight
      value: 6.51 g/cm3
      benchmark: density
      line: Zr 702 has a density of 6.51 g/cm3 and Zr 705 has 6.64 g/cm3. Zircaloy-4 is 6.55 g/cc.
    - label: Melting
      value: 1852 °C
      benchmark: melting_point
      line: Zr 702 melts at 1852 °C, Zr 705 at 1840 °C, and Zircaloy-4 at 1850 °C.
    - label: Strength when annealed
      value: 321.1 MPa yield
      line: Zr 702 typical yield strength is 321.1 MPa at room temperature, with an ASTM minimum of 207 MPa. Zr 705 is 506.1 MPa typical with a minimum of 379 MPa.
    - label: Strength when hot
      value: 97.2 MPa yield
      line: At 316 °C the typical yield strength of Zr 702 falls to 97.2 MPa.
  compare: The ATI data put Zr 702 at 22 W/(m·K) and 6.51 g/cm3, and Zr 705 at 17.1 W/(m·K) and 6.64 g/cm3. Zircaloy-4 has a density of 6.55 g/cc and conducts at 21.5 W/(m·K). Zr 702 has the higher conductivity, and Zr 705 is stronger at room temperature, with a typical tensile strength of 615.0 MPa against 468.1 MPa for Zr 702. Read the rows as grades of one metal, not as a ranking across all alloys.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Thermal expansion
      benchmark: cte
  handling:
    - Specify the grade (702, 705 or Zircaloy-4), since strength and conductivity differ between them.
    - Stress relieve after fabrication at 565 °C for 1/2 to 1 hour, and within 14 days after welding Zr 705.
    - Keep dry powder away from air. Wet it to at least 25 % water for storage and shipping.
  good_for:
    - 'Corrosion in hot nitric acid: 0.0 mpy for Zr 702 at 204 °C in 65 % nitric acid.'
    - 'Pressure equipment: approved under the ASME code, with allowable stress tables.'
    - 'Nuclear fuel cladding: Zircaloy-4 has a thermal neutron cross section of 0.22 barns.'
  watch_out:
    - Ferric and cupric chlorides and hydrofluoric acid attack both grades at more than 50 mpy.
    - Hydride cracking can embrittle Zircaloy cladding in reactor service.
    - 'Strength falls quickly when hot: 97.2 MPa yield at 316 °C for Zr 702.'
    - Dry powder can ignite spontaneously.
  verdict: Zirconium is the corrosion-resistant metal of choice for hot nitric acid and nuclear cladding, with Zr 702 and Zr 705 as the commercial grades. Dry powder is a fire hazard, the strength falls when hot, and chlorides and hydrofluoric acid attack it. The profile has no outgassing, cold-welding, or electrical resistivity values.
  recipe:
    line: Zirconium metal is made mainly by reducing zirconium(IV) chloride with magnesium, ZrCl4 + 2 Mg to Zr + 2 MgCl2 (Kroll process, Wikipedia). Zircaloy-4 is then made by adding tin, iron and chromium to zirconium (ATI, arXiv).
    parts:
      - name: Zirconium
        symbol: Zr
        atoms: 1
        atomic_weight: 91.22
        role: Base metal in Zr 702, Zr 705 and Zircaloy-4. Zr 702 is at least 99.2 % Zr plus Hf.
      - name: Tin
        symbol: Sn
        share_percent: 1.2
        share_high: 1.7
        role: Zircaloy-4 alloying element for corrosion resistance and strength (ATI composition table).
      - name: Iron
        symbol: Fe
        share_percent: 0.18
        share_high: 0.24
        role: Zircaloy-4 alloying element (ATI composition table).
      - name: Chromium
        symbol: Cr
        share_percent: 0.07
        share_high: 0.13
        role: Zircaloy-4 alloying element (ATI composition table).