Cartridge brass 70/30 C260

spore: profile
id: cartridge-brass
spore_version: 0.2
family: copper-alloys
name: Cartridge brass 70/30
abbreviation: C260
role: cold-working copper-zinc alloy
category: metals
type: copper-alloys
summary: |
  Cartridge brass 70/30 (UNS C26000, CuZn30, EN CW505L) is a copper-zinc alloy with 70 % copper and 30 % zinc, with lead held to 0.07 % maximum. It is the classic cold-forming brass: Aviva rates its capacity for being cold worked as excellent, and season cracking, named after the brass cartridges in which it was first found in the 1920s, is its classic failure mode. Its density is 8.53 g/cm3, its thermal conductivity is 121.2 W/(m·K) at 20 °C and its electrical conductivity is 28 %IACS at 68 °F. Its strength depends on temper: Aviva's typical 1 in values run from 324 MPa tensile in annealed OS050 to 524 MPa in hard H04, and Fisk's minimum round wire values are 540 MPa for H02 and 700 MPa for H04. The alloy is at risk from ammonia under residual stress, and a stress-relief anneal is the usual cure.
best_for: Cold-formed and deep-drawn parts such as cartridge cases, fasteners, pins and radiator parts, where good cold working and a ductile temper matter most
weakest_at: Season cracking in ammonia or amine atmospheres when residual stress from cold forming is left in the part
identity:
  formula: 'CuZn30, UNS C26000: copper 68.5 to 71.5 wt%, lead 0.07 wt% maximum, iron 0.05 wt% maximum, zinc remainder'
  source: aviva-c26000
  where: Chemical Composition table on the Aviva product page (Cu 68.5-71.5, Pb 0.07 max, Fe 0.05 max, Zn rem, nominal Cu 70 and Zn 30); the copper, zinc and lead limits also appear on the Fisk C260 page, and the iron limit on the Concast C26000 page.
  designations:
    - system: UNS
      code: C26000
      source: aviva-c26000
      where: 'Page title: C26000 Cartridge Brass "70/30"'
    - system: CDA
      code: C260
      source: fisk-c26000
      where: 'Page heading: C260 Cartridge Brass (CuZn30)'
    - system: EN name
      code: CuZn30
      source: aviva-c26000
      where: 'Line: EN equivalent for this alloy CuZn30'
    - system: EN name
      code: CW505L
      source: wieland-brass-alloys
      where: Brass alloys table, row M30 (M30/M34), EN No. column
    - system: JIS
      code: C2600
      source: wieland-brass-alloys
      where: Brass alloys table, row M30 (M30/M34), JIS-No. column
    - system: ASTM
      code: B36
      note: bar, sheet and plate, as listed on the Aviva page
      source: aviva-c26000
      where: Specifications list, ASTM B36 for bar, sheet and plate
    - system: Trade name
      code: Cartridge Brass
      source: fisk-c26000
      where: 'Page heading: C260 Cartridge Brass (CuZn30)'
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
    - electronics-and-chips
    - thermal-control
properties:
  - benchmark: density
    label: Density, C26000 (Aviva)
    value: 8.53
    unit: g/cm3
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temperature: 20 °C
      unit_in_source: 0.308 lb/in3 at 68 °F (US Customary column)
    method: Value printed in the metric column of a supplier's physical properties table; Concast prints the same 8.53 g/cm3
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Density row, metric column
  - benchmark: melting_point
    label: Solidus, C26000 (Aviva)
    value: 916
    unit: °C
    scope: material
    conditions:
      grade: C26000 (Aviva)
      unit_in_source: 1680 °F (US column)
      pressure: not stated
    method: Value printed in the metric column of a supplier's physical properties table; Concast prints 916 °C
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Melting Point Solid row, metric column
  - benchmark: melting_point
    label: Liquidus, C26000 (Aviva)
    value: 954
    unit: °C
    scope: material
    conditions:
      grade: C26000 (Aviva)
      unit_in_source: 1750 °F (US column)
      pressure: not stated
    method: Value printed in the metric column of a supplier's physical properties table; Concast prints 954 °C
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Melting Point Liquid row, metric column
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 20 °C, C26000 (Aviva)
    value: 121.2
    unit: W/(m·K)
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temperature: 20 °C
      temper: not stated; one value printed for the alloy
      unit_in_source: 70.0 Btu·ft/(hr·ft2·°F) at 68 °F (US column)
    method: Value printed in the metric column of a supplier's physical properties table; Concast prints 121.2 W/m K at 20 °C
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Thermal Conductivity row, metric column
  - benchmark: cte
    label: Coefficient of thermal expansion, 20 to 300 °C (Aviva)
    value: 20
    unit: ppm/K
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temperature: 20 to 300 °C
      temper: not stated
      unit_in_source: 20.0 per °C (20-300 °C)
    method: Printed as per °C; this is 10^-6 per kelvin, the same unit as ppm/K, so the number is copied without conversion
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Coefficient of Thermal Expansion row, metric column
  - benchmark: electrical_conductivity
    label: Electrical conductivity, C26000 (Aviva)
    value: 28
    unit: '%IACS'
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: not stated
      temperature: 68 °F (20 °C)
      unit_in_source: 28 %IACS at 68 °F (US column)
    method: Value printed in the US column of a supplier's physical properties table; the metric column for the same row (0.164 MegaSiemens/cm at 20 °C) is not converted here
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Electrical Conductivity row, US column
  - benchmark: electrical_resistivity
    label: Electrical resistivity, annealed C26000 (Aviva)
    value: 6.15
    unit: µΩ·cm
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: not stated in the Aviva row
      temperature: 20 °C
      unit_in_source: 37.0 ohms·cmil/ft at 68 °F (US column)
    method: Value printed in the metric column of a supplier's physical properties table
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Electrical Resistivity row, metric column
  - benchmark: elastic_modulus
    label: Modulus of elasticity in tension, C26000 (Aviva)
    value: 110000
    unit: MPa
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: not stated
      unit_in_source: 16000 ksi (US column)
    method: Value printed in the metric column of a supplier's physical properties table; the Fisk page prints 110 MPa for the same row, which is a units error and is not used
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Modulus of Elasticity in Tension row, metric column
  - benchmark: shear_modulus
    label: Modulus of rigidity, C26000 (Aviva)
    value: 41370
    unit: MPa
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: not stated
      unit_in_source: 6000 ksi (US column)
    method: Value printed in the metric column of a supplier's physical properties table
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Modulus of Rigidity row, metric column
  - benchmark: specific_heat
    label: Specific heat capacity, C26000 (Aviva)
    value: 377.1
    unit: J/(kg·K)
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temperature: 293 K (20 °C)
      unit_in_source: 0.09 Btu/lb/°F at 68 °F (US column)
    method: Value printed in the metric column of a supplier's physical properties table
    status: ground
    source: aviva-c26000
    where: Physical Properties table, Specific Heat Capacity row, metric column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, annealed OS050 flat product, 1 in rows (typical)
    value: 324
    unit: MPa
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: OS050, annealed
      product_form: flat product (sheet, strip and plate), 1 in rows
      basis: typical value, 20 °C
      unit_in_source: 47 ksi at 0.04 in rows (US column)
    method: Typical value (TYP) printed in a supplier's mechanical properties table by temper, metric 1 in row; not a minimum
    status: ground
    source: aviva-c26000
    where: Mechanical Properties by Temper table, flat products, row OS050, column Tensile 1 in (MPa)
  - benchmark: yield_strength
    label: Yield strength 0.05 % under load, annealed OS050 flat product, 1 in rows (typical)
    value: 103
    unit: MPa
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: OS050, annealed
      product_form: flat product (sheet, strip and plate), 1 in rows
      basis: typical value, 20 °C
      measure: 0.05 % under load
    method: Typical value (TYP) printed in a supplier's mechanical properties table, metric 1 in row; the yield definition is 0.05 % under load, not 0.2 % offset
    status: ground
    source: aviva-c26000
    where: Mechanical Properties by Temper table, flat products, row OS050, column YS 0.05% UL 1 in (MPa)
  - benchmark: elongation
    label: Elongation, annealed OS050 flat product, 1 in rows (typical)
    value: 62
    unit: '%'
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: OS050, annealed
      product_form: flat product (sheet, strip and plate), 1 in rows
      gauge_length: 1 in
      basis: typical value, 20 °C
    method: Typical value (TYP) printed in a supplier's mechanical properties table, metric 1 in row
    status: ground
    source: aviva-c26000
    where: Mechanical Properties by Temper table, flat products, row OS050, column Elong. 1 in (%)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, half-hard H02 flat product, 1 in rows (typical)
    value: 427
    unit: MPa
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: H02, half hard
      product_form: flat product (sheet, strip and plate), 1 in rows
      basis: typical value, 20 °C
      unit_in_source: 62 ksi at 0.04 in rows (US column)
    method: Typical value (TYP) printed in a supplier's mechanical properties table, metric 1 in row; not a minimum
    status: ground
    source: aviva-c26000
    where: Mechanical Properties by Temper table, flat products, row H02, column Tensile 1 in (MPa)
  - benchmark: yield_strength
    label: Yield strength 0.05 % under load, half-hard H02 flat product, 1 in rows (typical)
    value: 359
    unit: MPa
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: H02, half hard
      product_form: flat product (sheet, strip and plate), 1 in rows
      basis: typical value, 20 °C
      measure: 0.05 % under load
    method: Typical value (TYP) printed in a supplier's mechanical properties table, metric 1 in row
    status: ground
    source: aviva-c26000
    where: Mechanical Properties by Temper table, flat products, row H02, column YS 0.05% UL 1 in (MPa)
  - benchmark: elongation
    label: Elongation, half-hard H02 flat product, 1 in rows (typical)
    value: 25
    unit: '%'
    scope: material
    conditions:
      grade: C26000 (Aviva)
      temper: H02, half hard
      product_form: flat product (sheet, strip and plate), 1 in rows
      gauge_length: 1 in
      basis: typical value, 20 °C
    method: Typical value (TYP) printed in a supplier's mechanical properties table, metric 1 in row
    status: ground
    source: aviva-c26000
    where: Mechanical Properties by Temper table, flat products, row H02, column Elong. 1 in (%)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, half-hard H02 round wire (minimum)
    value: 540
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: C26000 (Fisk C260)
      temper: H02, 1/2 hard
      product_form: round wire, mill limits 0.0254 to 3.264 mm
      measure: minimum
      unit_in_source: 79.0 ksi (English column)
    method: Minimum value printed in a supplier's round wire temper table, metric column; wire, not rod, so not comparable with the flat-product rows
    status: ground
    source: fisk-c26000
    where: Round Wire table, metric block, row 1/2 Hard H02, column Tensile Strength Min (MPa)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, hard H04 round wire (minimum)
    value: 700
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: C26000 (Fisk C260)
      temper: H04, hard
      product_form: round wire, mill limits 0.0254 to 3.264 mm
      measure: minimum
      unit_in_source: 102 ksi (English column)
    method: Minimum value printed in a supplier's round wire temper table, metric column; wire, not rod
    status: ground
    source: fisk-c26000
    where: Round Wire table, metric block, row Hard H04, column Tensile Strength Min (MPa)
  - benchmark: machinability_rating
    label: Machinability rating, C26000 bar (supplier index)
    value: 30
    unit: '%'
    scope: material
    conditions:
      grade: C26000
      temper: not stated
      basis: relative index; the base (100 = reference alloy) is not printed on this page
    method: Index printed in the Fabrication table of the supplier's page; a relative rating, not a measured property
    status: ground
    source: aviva-c26000
    where: Fabrication table, Machinability rating row
corrosion:
  - environment: Ammonia or amine atmospheres with tensile stress (season cracking)
    headline: Season cracking was first found in brass cartridges in the 1920s, where cold-formed cases stored in ammonia-rich stables cracked.
    effect: The Hendrix Group says stress corrosion cracking needs both a high tensile stress and a specific corrosive environment, which for brasses is usually ammonia or amines, and that cold working such as pressing, spinning, drawing and bending leaves internal stresses that can cause cracking unless they are removed by stress relief. Wikipedia says the problem was resolved by annealing the cases and storing the cartridges elsewhere.
    rating: moderate
    conditions:
      basis: qualitative description for brasses in general; no threshold stress or time to crack for C26000 is printed in the sources
      test_example: 'Accelerated test cited by the Hendrix Group: air containing 10 % ammonia and 3.7 % water vapour at 35 °C (a test condition, not a service limit)'
    source: hgh-scc
    where: Sections on the environment, cold working and stress relief; Wikipedia Brass article, season cracking section
risks:
  hazards:
    - text: 'Lead: C26000 contains 0.07 wt% lead at most (Aviva and Fisk limits). The ATSDR ToxFAQ says lead can affect almost every organ and system, and that the U.S. Department of Health and Human Services has determined that lead and lead compounds are reasonably anticipated to be human carcinogens. No GHS code for the alloy was read.'
      ghs: []
      source: atsdr-lead
      where: ToxFAQs sections on health effects and cancer
  failure_risks:
    - mode: Season cracking in ammonia
      trigger: Tensile stress from cold forming (pressing, spinning, drawing, bending) together with an ammonia or amine atmosphere
      consequence: Cracking, which the Hendrix Group says is liable to occur longitudinally in drawn tube that has not been stress-relieved
      severity: moderate
      source: hgh-scc
      where: Cold working and stress relief sections
    - mode: Poor stress relaxation in spring service
      trigger: Use as a spring
      consequence: Fisk says the alloy has poor stress relaxation characteristics and does not make a particularly good spring material
      severity: low
      source: fisk-c26000
      where: Alloy description paragraph on the Fisk C260 page
  side_effects:
    - text: Concast lists C26000 under its lead-free products, while the same alloy carries up to 0.07 % lead
      affects: Potable-water plumbing (Concast lists plumbing among the uses of C26000)
      source: concast-c26000
      where: Lead-free products list and Plumbing row of the Concast C26000 page
  handling:
    - text: 'Specify the temper: Aviva''s typical 1 in flat values run from 324 MPa tensile in annealed OS050 to 524 MPa in hard H04, and Fisk''s round wire minimum runs from 540 MPa (H02) to 700 MPa (H04).'
      source: aviva-c26000
      where: Mechanical Properties by Temper table; Fisk Round Wire table
    - text: Stress-relieve parts after cold forming. The Hendrix Group says the optimum stress relief depends on the alloy and lies within one half to one hour at 250 to 300 °C for brasses.
      source: hgh-scc
      where: Stress relief paragraph
    - text: Keep parts out of ammonia and amine atmospheres in service.
      source: hgh-scc
      where: Environment section
    - text: Avoid exposure to sources of lead. The ATSDR advice applies to machining chips and dust from the alloy, which contain lead (this is our inference from the advice, not a statement in the source).
      source: atsdr-lead
      where: How can I protect my family from lead exposure
  mitigations:
    - text: The Hendrix Group says the higher the copper content, the better the resistance to stress corrosion cracking; C26000 is a 70 % copper alloy.
      source: hgh-scc
      where: Effect of composition section
    - text: Anneal the cases to remove the residual stress from cold forming and store the cartridges elsewhere, as was done after the 1920s British Indian Army failures (Wikipedia).
      source: wiki-brass
      where: Season cracking section
uses:
  - application: mechanisms
    device: Fasteners, pins, rivets and eyelets
    example: Concast lists eyelets, fasteners, grommets, pins, rivets and screws among the applications of C26000. Aviva lists springs, chain and bead chain as typical uses.
    source: concast-c26000
    where: Fasteners row of the Concast C26000 page; Typical Uses list on the Aviva page
  - application: electronics-and-chips
    device: Electrical terminals, lamp fixtures and flashlight shells
    example: Concast lists flashlight shells, lamp fixtures, reflectors, screw shells and terminal connectors under electrical uses. These are terrestrial uses; no source names a space system.
    source: concast-c26000
    where: Electrical row of the Concast C26000 page
  - application: thermal-control
    device: Radiator cores, radiator tanks and heat exchangers
    example: Concast lists radiator cores, radiator tanks and heater cores under automotive uses. Aviva lists heat exchangers among its typical uses. These are terrestrial uses; no source names a space system.
    source: concast-c26000
    where: Automotive row of the Concast C26000 page; Industrial row
supply:
  - subject: Copper (mine production, copper content, 2025e), about 70 % of the alloy
    producers:
      - country: Chile
        share_percent: 23
        year: 2025
      - country: Congo (Kinshasa)
        share_percent: 13.9
        year: 2025
      - country: Peru
        share_percent: 11.7
        year: 2025
      - country: China
        share_percent: 7.8
        year: 2025
      - country: Russia
        share_percent: 5.7
        year: 2025
    critical_lists:
      - list: U.S. Final 2025 List of Critical Minerals (copper added, per the USGS copper summary)
        listed: true
    recycling: 'USGS: brass and wire-rod mills accounted for approximately 80 % of the total copper recovered from scrap. Copper recovered from scrap contributed about 30 % of the U.S. copper supply.'
    substitutes: []
    source: usgs-mcs2026-copper
    where: World Mine and Refinery Production and Reserves table, mine production 2025e (world total 23,000 thousand t; shares calculated by Space Mushroom from the printed values 5,300, 3,200, 2,700, 1,800 and 1,300 thousand t); Critical minerals paragraph; Recycling paragraph
  - subject: Zinc (mine production, zinc content, 2025e), about 30 % of the alloy
    producers:
      - country: China
        share_percent: 31.5
        year: 2025
      - country: Peru
        share_percent: 11.5
        year: 2025
      - country: Australia
        share_percent: 8.5
        year: 2025
      - country: India
        share_percent: 6.7
        year: 2025
      - country: Mexico
        share_percent: 6
        year: 2025
    critical_lists: []
    recycling: 'USGS: refined zinc produced in the United States was recovered from secondary materials at both primary and secondary smelters, including galvanizing residues and crude zinc oxide from electric arc furnace dust.'
    substitutes:
      - 'USGS: aluminum and plastics substitute for galvanized sheet in automobiles; many elements are substitutes for zinc in chemical, electronic and pigment uses. The summary names no substitute for zinc in brass.'
    source: usgs-mcs2026-zinc
    where: World Mine Production and Reserves table, 2025e (world total 13,000 thousand t; shares calculated by Space Mushroom from the printed values 4,100, 1,500, 1,100, 870 and 780 thousand t); Recycling; Substitutes
documents:
  - title: 'Aviva Metals: C26000 Cartridge Brass "70/30" product page, chemical composition, physical properties, mechanical properties by temper, machinability'
    type: datasheet
    url: https://www.avivametals.com/collections/brass-alloys/yellow-brass/c26000-cartridge-brass-70-30
  - title: 'Fisk Alloy: C260 Cartridge Brass (CuZn30) product page, physical properties, round wire temper table, alloy description'
    type: datasheet
    url: https://fiskalloy.com/product/c26000/
  - title: 'Concast (Wieland): C26000 spec sheet, applications, composition, physical and mechanical properties'
    type: datasheet
    url: https://www.concast.com/c26000.php
  - title: 'Wieland: brass alloys table, row M30 (CuZn30, CW505L, C26000, C2600)'
    type: datasheet
    url: https://www.wieland.com/products/brass-alloys
  - title: 'Wikipedia: Brass (cartridge brass C260 row, season cracking, lead content)'
    type: database
    url: https://en.wikipedia.org/wiki/Brass
    year: 2026
  - title: 'The Hendrix Group archive: stress corrosion cracking (season cracking) of brasses'
    type: report
    url: https://hghouston.com/archive/material-property-data/copper-and-copper-alloys/brasses/sc-cracking
  - title: 'ATSDR ToxFAQs: Lead'
    type: report
    url: https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=93&toxid=22
  - title: 'USGS Mineral Commodity Summaries 2026: Copper'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Zinc'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.pdf
    year: 2026
gaps:
  - No dezincification statement or depth data for C26000 was read. The Aviva C26000 page has no dezincification note, and the Wikipedia passages read cover dezincification-resistant alloys, not this one.
  - The Hendrix test (10 % ammonia, 3.7 % water vapour, 35 °C) is an accelerated indicative test, not a service limit. No time to crack or threshold stress for C26000 was printed in the sources.
  - The Fisk C260 page prints a metric density of 8.94 g/cm3, which conflicts with its own 0.308 lb/in3 (8.53 g/cm3) and with Aviva and Concast. It also prints a melting range of 954 to 1,049 °C, which conflicts with Aviva and Concast (916 to 954 °C). Neither Fisk value is used.
  - The Fisk page prints an elastic modulus of 110 MPa, a units error. Aviva prints 110000 MPa, which is used.
  - Strength values are typical values from Aviva's flat-product and 1 in rod rows, and minimum values from Fisk's round wire table. No minimum for strip, sheet or rod against the ASTM B36 text was read, and the ASTM B36 text itself was not opened.
  - The hardness values on the Aviva table (Rockwell B 70 for H02, B 82 for H04) are not recorded; the hardness names are not in the property canon.
  - The machinability index of 30 is a supplier's relative rating. The base of the scale is not printed on the Aviva page.
  - 'Conflict on springs: Aviva lists springs among typical uses, while Fisk says the alloy does not make a particularly good spring material. Both are recorded in the file.'
  - 'Conflict on soldering: the Fisk and Aviva fabrication tables rate soldering as excellent. A Fisk sentence says the solderability is severely impaired by the high zinc content. The fabrication rating is not used and the sentence is not used.'
  - Lead is held to 0.07 % at most. No lead supply profile was written because lead is a trace element here, and the USGS lead summary was not used for this alloy.
  - Refined zinc net import reliance was not used because the column headers of the USGS table were not read.
  - No GHS classification or exposure limit for lead was read. The ATSDR ToxFAQ gives the health effects only.
  - No CAS number was read; the alloy is identified by its UNS number.
  - 'No space-environment data for C26000 were read: no outgassing, atomic-oxygen, cold-welding or radiation result. The tags.environments list is empty for this reason, and the applications listed are terrestrial uses.'
  - The National Bronze C26000 pages returned 404 and the PDF was not readable, so no National Bronze value is used.
  - 'Designations: BS, DIN and AFNOR codes were not read. The JIS code C2600 is from the Wieland table, which is a cross-reference table, not a JIS standard text.'
  - 'Media: no image was fetched or checked for this profile.'
sources:
  aviva-c26000:
    title: 'Aviva Metals, C26000 Cartridge Brass "70/30" product page: chemical composition, physical properties, mechanical properties by temper, fabrication ratings, typical uses'
    url: https://www.avivametals.com/collections/brass-alloys/yellow-brass/c26000-cartridge-brass-70-30
    kind: datasheet
    license: Supplier web page (cited, not reproduced)
  fisk-c26000:
    title: 'Fisk Alloy, C260 Cartridge Brass (CuZn30) product page: composition, physical properties, round wire temper table, alloy description'
    url: https://fiskalloy.com/product/c26000/
    kind: datasheet
    license: Supplier web page (cited, not reproduced)
  concast-c26000:
    title: 'Concast (Wieland), C26000 spec sheet: composition, physical and mechanical properties, applications, lead-free products list'
    url: https://www.concast.com/c26000.php
    kind: datasheet
    license: Manufacturer web page (cited, not reproduced)
  wieland-brass-alloys:
    title: 'Wieland: brass alloys table, row M30 (EN designation CuZn30, EN No. CW505L, ASTM UNS-No. C26000, JIS-No. C2600)'
    url: https://www.wieland.com/products/brass-alloys
    kind: datasheet
    license: Manufacturer web page (cited, not reproduced)
  wiki-brass:
    title: 'Brass (Wikipedia): cartridge brass C260 row, season cracking history, lead content'
    url: https://en.wikipedia.org/wiki/Brass
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  hgh-scc:
    title: 'The Hendrix Group, Material Property Data: copper and copper alloys, brasses, stress corrosion cracking'
    url: https://hghouston.com/archive/material-property-data/copper-and-copper-alloys/brasses/sc-cracking
    kind: web
    license: Technical archive page (cited, not reproduced)
  atsdr-lead:
    title: 'ATSDR ToxFAQs: Lead (Agency for Toxic Substances and Disease Registry, U.S. CDC)'
    url: https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=93&toxid=22
    kind: report
    license: U.S. government public domain (cited, not reproduced)
  usgs-mcs2026-copper:
    title: 'Mineral Commodity Summaries 2026: Copper'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-zinc:
    title: 'Mineral Commodity Summaries 2026: Zinc'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 19
  unreachable: 2
  caveats: 4
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable or unusable: National Bronze C26000 page (HTTP 404) and its PDF (not readable as text). Caveats: strength values are typical values from one supplier''s flat-product table and minimum values from one supplier''s round wire table, not from the ASTM B36 text; the Fisk metric density and melting range conflict with Aviva and Concast and were not used; the Fisk elastic modulus has a units error and was not used; the season-cracking test is accelerated and qualitative.'
story:
  risk_groups:
    - title: For people
      lead: The lead in C26000 is the main health concern in these sources. They give the health effects of lead but no exposure limit for brass dust.
      level: 2
      verdict: Low-lead alloy
      points:
        - label: Lead in the alloy
          line: C26000 has 0.07 % lead at most (Aviva and Fisk). The ATSDR says lead can affect almost every organ and system, and the U.S. Department of Health and Human Services considers lead and lead compounds reasonably anticipated to be human carcinogens.
        - label: Lead-free listing
          line: Concast lists C26000 under its lead-free products. The source does not give the lead-free limit it uses.
    - title: If it fails
      lead: The failure route in these sources is chemical (ammonia) and it is driven by residual stress from cold forming.
      points:
        - label: Season cracking
          line: Cold forming leaves stress, and in an ammonia or amine atmosphere the alloy can crack. The Hendrix Group describes the cracking, and Wikipedia records the 1920s cartridge failures.
        - label: Stiff springs
          line: Fisk says the alloy has poor stress relaxation and does not make a particularly good spring material, although Aviva lists springs among its uses.
    - title: Handling and storage
      points:
        - label: Pick the temper
          line: Annealed OS050 flat product has 324 MPa typical tensile strength and 62 % elongation. Half-hard H02 has 427 MPa and 25 %. Hard H04 has 524 MPa and 8 %.
        - label: Stress relief
          line: Stress-relieve parts after cold forming, as the Hendrix Group advises, and keep them out of ammonia and amine atmospheres.
  why: Cartridge brass is chosen for cold working. Aviva rates its capacity for being cold worked as excellent, and Fisk rates cold working as excellent too. It conducts heat at 121.2 W/(m·K) at 20 °C (Aviva) and electricity at 28 %IACS. Its density is 8.53 g/cm3. The lead content is at most 0.07 %, and the alloy's main weakness is season cracking in ammonia.
  uses:
    - where: Fasteners, pins and rivets
      line: Concast lists eyelets, fasteners, grommets, pins, rivets and screws among the applications of C26000. Aviva lists springs, chain and bead chain as typical uses.
    - where: Electrical parts and lamp fixtures
      line: Concast lists flashlight shells, lamp fixtures, reflectors, screw shells and terminal connectors. These are terrestrial uses; no source names a space system.
    - where: Radiator and heat-exchanger parts
      line: Concast lists radiator cores, radiator tanks and heater cores. Aviva lists heat exchangers among its typical uses.
  can_do:
    - label: Form cold
      value: Excellent cold-working rating
      line: Aviva and Fisk both rate the capacity for being cold worked as excellent, and Aviva's flat product reaches 62 % elongation in the annealed OS050 temper.
    - label: Carry heat
      value: 121.2 W/(m·K)
      benchmark: thermal_conductivity
      line: Thermal conductivity is 121.2 W/(m·K) at 20 °C (Aviva, metric column).
    - label: Carry current
      value: 28 %IACS
      line: Electrical conductivity is 28 %IACS at 68 °F (Aviva, US column).
    - label: Strength by temper
      value: 324 to 524 MPa typical
      line: Aviva's typical tensile strength for flat product runs from 324 MPa annealed (OS050) to 524 MPa in H04. Fisk's minimum round wire values are 540 MPa for H02 and 700 MPa for H04.
    - label: Weight
      value: 8.53 g/cm3
      benchmark: density
      line: Density is 8.53 g/cm3 at 20 °C (Aviva, metric column).
    - label: Melting
      value: 916 to 954 °C
      line: The solidus is 916 °C and the liquidus is 954 °C (Aviva, metric column).
    - label: Expansion
      value: 20.0 ppm/K
      benchmark: cte
      line: The coefficient of thermal expansion is 20.0 ppm/K over 20 to 300 °C (Aviva, printed as per °C).
  compare: The [copper profile](/profiles/copper/) covers the pure metal. The free-cutting brass profile in this set is the machinability reference among the brasses; C26000 has a supplier machinability rating of 30, and it is the better choice where cold forming matters more than machining.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Thermal expansion
      benchmark: cte
  handling:
    - 'Specify the temper: strength runs from 324 MPa typical in annealed OS050 flat product to 524 MPa in hard H04 flat product.'
    - Stress-relieve after cold forming (pressing, spinning, drawing, bending), and keep parts out of ammonia and amine atmospheres.
    - The alloy contains lead at 0.07 % at most, so machining chips and dust are a lead source; the ATSDR advice to avoid lead exposure applies to them (this is our inference from the advice, not a statement in the source).
  good_for:
    - Cold-formed and deep-drawn parts, where excellent cold working and a ductile temper are the main selection criteria.
    - Fasteners, pins and rivets that need a tensile strength between about 324 MPa (annealed) and 524 MPa (H04), chosen by temper.
    - Radiator and heat-exchanger parts that need good thermal conductivity, at 121.2 W/(m·K).
  watch_out:
    - Season cracking in ammonia or amine atmospheres when cold-forming stress is left in the part.
    - Aviva lists springs among its uses, but Fisk says the alloy does not make a good spring material because of its poor stress relaxation.
    - Lead at 0.07 % at most is still a health hazard in the sources.
    - The machinability rating of 30 is a supplier's relative index, and it is a poor choice where machinability is the main criterion.
  verdict: Cartridge brass 70/30 is the classic cold-forming brass. It gives 121.2 W/(m·K) thermal conductivity and 28 %IACS conductivity, with typical tensile strength from 324 to 524 MPa across the temper range, and it is rated excellent for cold working. Its main weakness is season cracking in ammonia when residual stress from forming is left in the part, and the fix is a stress-relief anneal. No dezincification data, no corrosion rate and no space-environment result were found in the pages read.
  recipe:
    line: Cartridge brass is a copper-zinc alloy with 68.5 to 71.5 % copper, zinc as the remainder (nominal 30 %), and at most 0.07 % lead. Aviva and Concast also print the 0.05 % iron limit.
    parts:
      - name: Copper
        symbol: Cu
        share: 68.5 to 71.5 wt% (nominal 70 wt%)
        role: Main metal and matrix of the alloy (limits from Aviva, Fisk and Concast).
      - name: Zinc
        symbol: Zn
        share: remainder (nominal 30 wt%)
        role: The alloying element that makes the brass. Wikipedia's alloy table notes good cold working properties for C260 and says it is used for ammunition cases, plumbing and hardware.
      - name: Lead
        symbol: Pb
        share: 0.07 wt% maximum
        role: Impurity limit printed on the Aviva, Fisk and Concast pages.
      - name: Iron
        symbol: Fe
        share: 0.05 wt% maximum
        role: Impurity limit printed on the Aviva and Concast pages.