Leaded tin bronze C94300 (high-leaded tin bronze) C943

spore: profile
id: leaded-tin-bronze-c94300
spore_version: 0.2
family: copper-alloys
name: Leaded tin bronze C94300 (high-leaded tin bronze)
abbreviation: C943
role: cast copper-tin-lead bearing and bushing alloy
category: metals
type: copper-alloys
summary: |
  Leaded tin bronze C94300 (UNS C94300, sold as high-leaded tin bronze or soft bronze) is a copper alloy with 23 to 27 % lead and 4.5 to 6 % tin, per the ICAST ASME SB-505 limits. Its density is 9.3 g/cm3 at 20 °C (Concast) and its thermal conductivity is 62.7 W/mK at 20 °C (AZoM). The sources give a minimum tensile strength of 145 MPa (Concast, ICAST), and the lead makes it free-cutting and lubricious. It is used for high-speed bearings, bushings and railroad parts.
best_for: 'Bearings and bushings: Concast says the lead gives good lubricity and the alloy envelopes foreign matter, and the machinability rating is 80'
weakest_at: 'Strength: 145 MPa minimum tensile strength (Concast, ICAST), against 185 MPa in AZoM, and brazing is rated poor (Concast)'
identity:
  formula: 'Cu-Sn-Pb cast bronze, UNS C94300, ASTM B505 composition: copper 67 to 72 %, lead 23 to 27 %, tin 4.5 to 6 %; zinc 0.8 max, iron 0.15 max, antimony 0.8 max, nickel plus cobalt 1 max, phosphorus 1.5 max, sulphur 0.08 max, aluminium 0.005 max, silicon 0.005 max (wt %)'
  source: icast-sb505
  where: Chemical Composition table of the ICAST ASME SB-505 C94300 sheet (Cu 67.000 to 72.000 %, Pb 23.000 to 27.000 %, Sn 4.500 to 6.000 %); the Concast page prints the same ranges for Cu, Pb and Sn
  designations:
    - system: UNS
      code: C94300
      source: concast-c94300
      where: Page title and Machinability table, row Copper alloy UNS No.
    - system: ASTM
      code: B505
      source: concast-c94300
      where: Chemical composition heading, ASTM B505/B505M-23
    - system: ASTM
      code: B144‐3E
      source: icast-sb505
      where: Cross Reference Table, row B144-3E, standard ASTM
    - system: SAE
      code: J461
      source: concast-c94300
      where: Similar or equivalent specification table, SAE column
    - system: SAE
      code: J462
      source: concast-c94300
      where: Similar or equivalent specification table, SAE column
    - system: SAE
      code: CA943
      source: icast-sb505
      where: Cross Reference Table, row CA943, standard SAE
    - system: Federal
      code: QQ-C-390
      source: concast-c94300
      where: Similar or equivalent specification table, Federal column
    - system: MIL
      code: MIL-B-16261
      note: Grade V
      source: concast-c94300
      where: Similar or equivalent specification table, Military column
    - system: Trade name
      code: Soft Bronze
      note: generic name printed in the Other column, not a brand
      source: concast-c94300
      where: Similar or equivalent specification table, Other column
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
properties:
  - benchmark: density
    label: Density, leaded tin bronze C94300
    value: 9.3
    unit: g/cm3
    scope: material
    conditions:
      grade: C94300 (high-leaded tin bronze)
      temperature: 20 °C
      unit_in_source: 9.3 gm/cm3 at 20 °C
    method: Value printed in the physical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    source: concast-c94300
    where: Physical properties table, row Density, metric column
  - benchmark: density
    label: Density, leaded tin bronze C94300 (AZoM)
    value: 9.29
    unit: g/cm3
    scope: material
    conditions:
      grade: C94300
      temperature: not stated
      unit_in_source: 0.336 lb/in3
    method: Value printed in the physical properties table of an AZoM copper alloy article
    status: ground
    note: Concast prints 9.3 g/cm3 at 20 °C for the same alloy; the two values agree to rounding.
    source: azom-c94300
    where: Physical Properties table, row Density, metric column
  - benchmark: density
    label: Density, leaded tin bronze C94300 (Aviva Metals)
    value: 8.86
    unit: g/cm3
    scope: material
    conditions:
      grade: C94300
      temperature: 20 °C
      unit_in_source: 8.86 gm/cm3 @ 20 C
    method: Value printed in the Physical Properties table of a supplier product page
    status: ground
    note: Concast prints 9.3 g/cm3 and AZoM prints 9.29 g/cm3 for the same alloy. The sources disagree and all are recorded.
    source: avivametals-c94300
    where: Physical Properties table, row Density, metric column
  - benchmark: electrical_conductivity
    label: Electrical conductivity, leaded tin bronze C94300
    value: 9
    unit: '%IACS'
    scope: material
    conditions:
      grade: C94300
      temperature: 68 °F (20 °C)
      unit_in_source: 9% IACS at 68 °F
    method: Value printed in the physical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    source: concast-c94300
    where: Physical properties table, row Electrical conductivity, US customary column
  - benchmark: thermal_conductivity
    label: Thermal conductivity, leaded tin bronze C94300
    value: 62.7
    unit: W/mK
    scope: material
    conditions:
      grade: C94300
      temperature: 20 °C
      unit_in_source: 62.7 W/mK
    method: Value printed in the thermal properties table of an AZoM copper alloy article
    status: ground
    note: Concast prints the same figure, 62.7 W/m at 20 °C, in its physical properties table, with the unit printed without the K.
    source: azom-c94300
    where: Thermal Properties table, row Thermal conductivity (@ 20 °C/68 °F), metric column
  - benchmark: thermal_conductivity
    label: Thermal conductivity, leaded tin bronze C94300 (Aviva Metals)
    value: 54
    unit: W/mK
    scope: material
    conditions:
      grade: C94300
      temperature: 20 °C
      unit_in_source: 54.0 W/m · oK at 20 C
    method: Value printed in the Physical Properties table of a supplier product page
    status: ground
    note: Concast and AZoM print 62.7 W/mK at 20 °C for the same alloy. The sources disagree and all are recorded.
    source: avivametals-c94300
    where: Physical Properties table, row Thermal Conductivity, metric column
  - benchmark: specific_heat
    label: Specific heat capacity, leaded tin bronze C94300
    value: 377.1
    unit: J/kg
    scope: material
    conditions:
      grade: C94300
      temperature: 20 °C
      unit_in_source: 377.1 J/kg at 20 °C
    method: Value printed in the physical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    source: concast-c94300
    where: Physical properties table, row Specific heat capacity, metric column
  - benchmark: elastic_modulus
    label: Modulus of elasticity in tension, leaded tin bronze C94300 (Concast)
    value: 72400
    unit: MPa
    scope: material
    conditions:
      grade: C94300
      temperature: not stated
      unit_in_source: 10500 ksi
    method: Value printed in the physical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    note: AZoM prints 117 GPa for the same alloy; the two sources disagree and both are recorded.
    source: concast-c94300
    where: Physical properties table, row Modulus of elasticity in tension, metric column
  - benchmark: elastic_modulus
    label: Elastic modulus, leaded tin bronze C94300 (AZoM)
    value: 117
    unit: GPa
    scope: material
    conditions:
      grade: C94300
      temperature: not stated
      unit_in_source: 17000 ksi
    method: Value printed in the mechanical properties table of an AZoM copper alloy article
    status: ground
    note: Concast prints 72400 MPa for the same alloy; the two sources disagree and both are recorded.
    source: azom-c94300
    where: Mechanical Properties table, row Elastic modulus, metric column
  - benchmark: incipient_melting_temperature
    label: Incipient melting temperature, leaded tin bronze C94300
    value: 316
    unit: °C
    scope: material
    conditions:
      grade: C94300
      unit_in_source: 600 °F
      note: incipient melting point as printed; no solidus or liquidus range is printed on the sources read
    method: Value printed in the physical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    source: concast-c94300
    where: Physical properties table, row Incipient Melting, metric column
  - benchmark: melting_point
    label: Solidus, leaded tin bronze C94300 (Aviva Metals)
    value: 904
    unit: °C
    scope: material
    conditions:
      grade: C94300
      unit_in_source: 1660 F
    method: Value printed in the Physical Properties table of a supplier product page
    status: ground
    note: The incipient melting temperature of 316 °C from Concast is far below this solidus. No source read explains the difference, and both are recorded.
    source: avivametals-c94300
    where: Physical Properties table, row Melting Point - Solidus, metric column
  - benchmark: melting_point
    label: Liquidus, leaded tin bronze C94300 (Aviva Metals)
    value: 1027
    unit: °C
    scope: material
    conditions:
      grade: C94300
      unit_in_source: 1880 F
    method: Value printed in the Physical Properties table of a supplier product page
    status: ground
    source: avivametals-c94300
    where: Physical Properties table, row Melting Point - Liquidus, metric column
  - benchmark: elastic_modulus
    label: Modulus of elasticity in tension, leaded tin bronze C94300 (Aviva Metals)
    value: 103400
    unit: MPa
    scope: material
    conditions:
      grade: C94300
      temperature: not stated
      unit_in_source: 10500 ksi
    method: Value printed in the Physical Properties table of a supplier product page
    status: ground
    note: Concast prints 72400 MPa and AZoM prints 117 GPa for the same alloy. The sources disagree and all are recorded.
    source: avivametals-c94300
    where: Physical Properties table, row Modulas of Elasticity in Tension, metric column
  - benchmark: poissons_ratio
    label: Poisson's ratio, leaded tin bronze C94300
    value: 0.34
    unit: '-'
    scope: material
    conditions:
      grade: C94300
      temperature: not stated
    method: Value printed in the mechanical properties table of an AZoM copper alloy article
    status: ground
    source: azom-c94300
    where: Mechanical Properties table, row Poisson's ratio
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, leaded tin bronze C94300, minimum (ASTM B505)
    value: 145
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: C94300, continuous casting, as cast
      standard: ASTM B505/B505M-23
      unit_in_source: 21 ksi
    method: Minimum value printed in the mechanical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    note: ICAST prints the same 145 MPa minimum for ASME SB-505 C94300 (as-cast).
    source: concast-c94300
    where: Mechanical properties table, row Tensile strength, metric MPa column, minimum
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, leaded tin bronze C94300 (AZoM)
    value: 185
    unit: MPa
    scope: material
    conditions:
      grade: C94300
      temperature: not stated
      note: AZoM does not say whether this is a minimum or a typical value
      unit_in_source: 26800 psi
    method: Value printed in the mechanical properties table of an AZoM copper alloy article
    status: ground
    note: Concast gives a minimum of 145 MPa for the same alloy. The two sources disagree and both are recorded.
    source: azom-c94300
    where: Mechanical Properties table, row Tensile strength, metric column
  - benchmark: yield_strength
    label: Yield strength at 0.5 % extension, leaded tin bronze C94300, minimum
    value: 103
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: C94300, continuous casting, as cast
      measure: 0.5 % extension under load
      unit_in_source: 15 ksi
    method: Minimum value printed in the mechanical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    source: concast-c94300
    where: Mechanical properties table, row Yield strength at 0.5 % extension under load, metric MPa column, minimum
  - benchmark: yield_strength
    label: Yield strength at 0.500 % extension, leaded tin bronze C94300 (AZoM)
    value: 90
    unit: MPa
    scope: material
    conditions:
      grade: C94300
      measure: 0.500 % extension under load
      unit_in_source: 13100 psi
    method: Value printed in the mechanical properties table of an AZoM copper alloy article
    status: ground
    note: Concast gives a minimum of 103 MPa at 0.5 % extension. The two sources disagree and both are recorded.
    source: azom-c94300
    where: Mechanical Properties table, row Yield strength (@ 0.500%), metric column
  - benchmark: elongation
    label: Elongation, leaded tin bronze C94300, minimum
    value: 7
    bound: lower
    unit: '%'
    scope: material
    conditions:
      grade: C94300, continuous casting, as cast
      gauge_length: 2 in or 50 mm
    method: Minimum value printed in the mechanical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    source: concast-c94300
    where: Mechanical properties table, row Elongation in 2 in. or 50 mm, min (%)
  - benchmark: elongation
    label: Elongation at break, leaded tin bronze C94300 (AZoM)
    value: 10
    unit: '%'
    scope: material
    conditions:
      grade: C94300
      gauge_length: 50 mm
    method: Value printed in the mechanical properties table of an AZoM copper alloy article
    status: ground
    note: Concast gives a minimum of 7 % in 2 in or 50 mm. The two sources disagree and both are recorded.
    source: azom-c94300
    where: Mechanical Properties table, row Elongation at break (in 50 mm)
  - benchmark: brinell_hardness
    label: Brinell hardness, leaded tin bronze C94300, typical
    value: 45
    unit: BHN
    scope: material
    conditions:
      grade: C94300
      load: 500 kg
      basis: typical value, not a minimum
    method: Typical value printed in the mechanical properties table of a manufacturer product page (data provided by CDA)
    status: ground
    source: concast-c94300
    where: Mechanical properties table, column Brinell hardness (500 kg load), typical BHN
  - benchmark: machinability_rating
    label: Machinability rating, leaded tin bronze C94300
    value: 80
    unit: '-'
    scope: material
    conditions:
      grade: C94300
      reference: free-cutting brass UNS C36000 = 100
    method: Rating printed in the mechanical properties table of an AZoM copper alloy article, with the reference alloy printed
    status: ground
    source: azom-c94300
    where: Mechanical Properties table, row Machinability (UNS C36000 (free-cutting brass) = 100)
  - benchmark: machinability_rating
    label: Machinability rating, leaded tin bronze C94300 (Conex Casting)
    value: 80
    unit: '-'
    scope: material
    conditions:
      grade: C943 (UNS C94300)
      reference: reference alloy not printed on this page
    method: Rating printed in the Machinability section of a foundry product page
    status: ground
    note: AZoM prints the same rating of 80 for this alloy.
    source: conex-c94300
    where: Machinability section, row Machinability Rating
corrosion: []
risks:
  hazards:
    - text: The lead safety data sheet, signal word Danger, prints H360 (May damage fertility or the unborn child), H362 (May cause harm to breast-fed children) and H372 (Causes damage to organs through prolonged or repeated exposure if swallowed, central nervous system, blood, immune system and kidney). It describes lead metal, not this alloy, which contains 23 to 27 % lead.
      ghs:
        - H360
        - H362
        - H372
      source: trace-lead-sds
      where: Section 2, hazard statements H360, H362 and H372; signal word Danger
  failure_risks:
    - mode: Hot shortness during brazing
      trigger: Brazing, or cooling after brazing, with strain on the part
      consequence: Concast says brazing is performed within the hot-short range, so strain must be avoided during brazing and cooling. Brazing is rated poor.
      severity: moderate
      source: concast-c94300
      where: Fabrication properties table, row Brazing, and its footnote
  side_effects: []
  handling:
    - text: 'Solder rather than braze: Concast rates soldering good and brazing poor.'
      source: concast-c94300
      where: Fabrication properties table, rows Soldering and Brazing
    - text: 'Do not use oxyacetylene welding or gas shielded arc welding: Concast says both are not recommended.'
      source: concast-c94300
      where: Fabrication properties table, rows Oxyacetylene welding and Gas shielded arc welding
  mitigations: []
uses:
  - application: mechanisms
    device: High-speed bearings and bushings
    example: Concast lists high-speed bearings for light loads and high-speed or light-to-medium pressure bushings among the typical uses of high-leaded tin bronze.
    source: concast-c94300
    where: Typical uses and applications list, Industrial
  - application: mechanisms
    device: Railroad parts and soft bushings
    example: Concast lists railroad applications, soft bushings and soft metal applications among the typical uses.
    source: concast-c94300
    where: Typical uses and applications list
supply:
  - subject: Copper (67 to 72 % of the alloy)
    abundance: USGS 2026 reports world copper mine production of 23,000 in 2025e, led by Chile at 5,300, Congo (Kinshasa) at 3,200 and Peru at 2,700 (table units).
    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, 90 FR 50494)
        listed: true
    substitutes:
      - 'USGS: aluminum substitutes for copper in electrical equipment and power cable, and optical fiber substitutes for copper in telecommunications applications.'
    source: usgs-mcs2026-copper
    where: World Mine and Refinery Production and Reserves table, mine production 2025e; shares calculated from the mine production figures; Critical minerals text; Substitutes
  - subject: Lead (23 to 27 % of the alloy)
    abundance: USGS 2026 reports world lead mine production of 4,500 in 2025e, led by China at 1,900, Australia at 480 and Peru at 290 (table units).
    producers:
      - country: China
        share_percent: 42.2
        year: 2025
      - country: Australia
        share_percent: 10.7
        year: 2025
      - country: Peru
        share_percent: 6.4
        year: 2025
      - country: Russia
        share_percent: 5.8
        year: 2025
    critical_lists:
      - list: U.S. Final 2025 List of Critical Minerals (lead added, 90 FR 50494)
        listed: true
    recycling: 'USGS: in 2025 an estimated 1 million tons of secondary lead was produced in the United States, equivalent to 70% of apparent domestic consumption, nearly all from old scrap, mostly lead-acid batteries.'
    substitutes:
      - 'USGS: tin has replaced lead in solder for potable water systems; steel and zinc are common substitutes for lead in wheel weights.'
    source: usgs-mcs2026-lead
    where: World Mine Production and Reserves table, mine production 2025e (shares calculated); Recycling; Substitutes; Critical minerals text
  - subject: Tin (4.5 to 6 % of the alloy)
    abundance: USGS 2026 reports world tin mine production of 290,000 in 2025e, led by China at 71,000, Indonesia at 61,000 and Peru at 33,000 (table units).
    producers:
      - country: China
        share_percent: 24.5
        year: 2025
      - country: Indonesia
        share_percent: 21
        year: 2025
      - country: Peru
        share_percent: 11.4
        year: 2025
      - country: Brazil
        share_percent: 9.7
        year: 2025
      - country: Congo (Kinshasa)
        share_percent: 9.3
        year: 2025
    critical_lists: []
    source: usgs-mcs2026-tin
    where: World Mine Production and Reserves table, mine production 2025e (shares calculated from the world total of 290,000)
documents:
  - title: Concast, C94300 high-leaded tin bronze product page (composition, physical, mechanical and designation tables)
    type: datasheet
    url: https://concast.com/c94300.php
  - title: AZoM, Copper Alloy (UNS C94300)
    type: database
    url: https://www.azom.com/article.aspx?ArticleID=9015
  - title: ICAST Alloys LLP, ASME SB-505 C94300 continuous casting data sheet
    type: datasheet
    url: https://www.icastllp.com/material_db_pdf/ASME%20SB-505%20C94300.pdf
  - title: Trace Sciences International, Lead safety data sheet (laboratory research grade)
    type: sds
    url: https://tracesciences.com/wp-content/uploads/2025/04/Lead-SDS.pdf
  - 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: Lead'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Tin'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
  - title: Aviva Metals, C94300 high-leaded tin bronze (soft bronze) product page
    type: datasheet
    url: https://www.avivametals.com/collections/bronze-alloys/leaded-bronze/c94300-high-leaded-tin-bronze-soft-bronze
  - title: Conex Casting, C94300 (CDA 943) leaded tin bronze page
    type: datasheet
    url: https://conex-casting.com/c94300-cda-943-leaded-tin-bronze-alloys/
gaps:
  - 'Corrosion and seawater resistance of C94300: no corrosion rate, environment or rating was printed on any source read in this run. The Concast page has no corrosion text, and the copper.org alloy page returned HTTP 403.'
  - 'EN number and EN name: no EN designation is printed for C94300 on any source read. The Concast page says it gives no EN designation, so none is entered.'
  - 'Composition conflict: AZoM prints copper 68.5 to 73.5 %, lead 22 to 25 % and tin 4.5 to 6 %, while ICAST prints copper 67 to 72 %, lead 23 to 27 % and tin 4.5 to 6 %. The Concast table gives the same ICAST ranges with a note that its column mapping is uncertain. The ICAST ASME SB-505 limits are used in the composition; the AZoM figures are not used as limits.'
  - 'Strength conflict: Concast and ICAST give a minimum tensile strength of 145 MPa and a minimum yield strength of 103 MPa at 0.5 % extension, while AZoM gives 185 MPa tensile and 90 MPa yield without saying whether these are minimum or typical. Both are recorded and neither is preferred.'
  - 'Elastic modulus conflict: Concast prints 72400 MPa and AZoM prints 117 GPa for the same alloy. Both are recorded.'
  - 'Melting range: the Aviva Metals page prints a solidus of 904 °C and a liquidus of 1027 °C. Concast prints an incipient melting temperature of 316 °C (600 °F), recorded under the name incipient_melting_temperature because it is not a canonical property. The two are not reconciled by any source read.'
  - 'Electrical conductivity (9 %IACS, Concast) and Brinell hardness (typical 45 BHN, Concast) and machinability rating (80, AZoM) are recorded under names that are not in the canonical property list: electrical_conductivity, brinell_hardness and machinability_rating.'
  - The ASTM B505/B505M-23 standard itself is not readable here. Its limits are taken from the printed ICAST and Concast copies, which are not identical in the composition column mapping.
  - The lead safety data sheet read is for laboratory-grade lead metal, not for the alloy. No SDS for C94300 itself was found, and no occupational exposure limit for lead was recorded.
  - 'Tin critical-list status: the USGS 2026 tin summary read in this run does not mention the critical minerals list, so critical_lists for tin is empty.'
  - 'Copper substitutes: the USGS copper summary was used for copper substitutes; no alloy-specific substitute was read.'
  - Fatigue, creep, outgassing, atomic oxygen erosion, cold welding, thermal cycling and low-temperature data for C94300 were not searched and no values are recorded.
  - Atomic weights were not read in this run, so the recipe parts carry weight shares only.
sources:
  concast-c94300:
    title: Concast, C94300 high-leaded tin bronze product page
    url: https://concast.com/c94300.php
    kind: datasheet
    license: Manufacturer product page (cited, not reproduced)
  azom-c94300:
    title: AZoM, Copper Alloy (UNS C94300)
    url: https://www.azom.com/article.aspx?ArticleID=9015
    kind: web
    license: Web article (cited, not reproduced)
  icast-sb505:
    title: ICAST Alloys LLP, ASME SB-505 C94300 continuous casting data sheet
    url: https://www.icastllp.com/material_db_pdf/ASME%20SB-505%20C94300.pdf
    kind: datasheet
    license: Supplier data sheet (cited, not reproduced)
  trace-lead-sds:
    title: Trace Sciences International, Lead safety data sheet (laboratory research grade)
    url: https://tracesciences.com/wp-content/uploads/2025/04/Lead-SDS.pdf
    kind: datasheet
    license: Supplier safety data sheet (cited, not reproduced)
  avivametals-c94300:
    title: Aviva Metals, C94300 high-leaded tin bronze (soft bronze) product page
    url: https://www.avivametals.com/collections/bronze-alloys/leaded-bronze/c94300-high-leaded-tin-bronze-soft-bronze
    kind: web
    license: Supplier web page (cited, not reproduced)
  conex-c94300:
    title: Conex Casting, C94300 (CDA 943) leaded tin bronze page
    url: https://conex-casting.com/c94300-cda-943-leaded-tin-bronze-alloys/
    kind: datasheet
    license: Foundry web page (cited, not reproduced)
  usgs-mcs2026-copper:
    title: Mineral Commodity Summaries 2026, Copper
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-lead:
    title: Mineral Commodity Summaries 2026, Lead
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-tin:
    title: Mineral Commodity Summaries 2026, Tin
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
story:
  why: Leaded tin bronze C94300 is a copper alloy with 23 to 27 % lead and 4.5 to 6 % tin, sold as high-leaded tin bronze or soft bronze. Concast says the lead makes the alloy free cutting and gives it good lubricity for bearings. The ICAST ASME SB-505 limits give a minimum tensile strength of 145 MPa, but AZoM prints 185 MPa, so the sources disagree on strength.
  risk_groups:
    - title: For people
      lead: The main hazard comes from the lead in the alloy, as the lead safety data sheet describes it.
      level: 2
      verdict: 'Lead: fertility and organ harm'
      points:
        - label: Hazard statements
          line: 'The lead safety data sheet, signal word Danger, prints H360, H362 and H372: it may damage fertility or the unborn child, may harm breast-fed children, and causes organ damage through prolonged or repeated exposure if swallowed.'
        - label: Source of the data
          line: That sheet describes lead metal, not this alloy. No safety data sheet for C94300 itself was read in this run.
    - title: If it fails
      lead: The failure route in the sources is brazing.
      points:
        - label: Hot shortness
          line: Concast says brazing is performed within the hot-short range, so strain must be avoided during brazing and cooling.
    - title: Handling and welding
      points:
        - label: Joining
          line: Concast rates soldering good and brazing poor, and says oxyacetylene welding and gas shielded arc welding are not recommended.
  uses:
    - where: Bearings and bushings
      line: Concast lists high-speed bearings for light loads and high-speed or light-to-medium pressure bushings among its typical uses.
    - where: Railroad parts and soft bushings
      line: Concast lists railroad applications, soft bushings and soft metal applications among its typical uses.
  can_do:
    - label: Carry a minimum load
      value: 145 MPa minimum
      benchmark: ultimate_tensile_strength
      line: The ICAST ASME SB-505 limit for the as-cast alloy is 145 MPa minimum tensile strength, and Concast prints the same minimum.
    - label: Machine freely
      value: '80'
      benchmark: machinability_rating
      line: AZoM gives a machinability rating of 80, with free-cutting brass UNS C36000 at 100 as the reference.
    - label: Take the density
      value: 9.3 g/cm3
      benchmark: density
      line: Concast gives a density of 9.3 g/cm3 at 20 °C.
  compare: 'Among copper alloys, C94300 is a soft, cast-type bearing alloy: its strength is set by the lead and tin content rather than by work hardening. Compare it with the phosphor bronze profile, a wrought spring alloy, and the copper profile, which is a different, nearly pure grade. The three rows below show the density, thermal conductivity and elastic modulus recorded here.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Elastic modulus
      benchmark: elastic_modulus
  handling:
    - Solder rather than braze, since brazing is rated poor.
    - Keep strain off the part during brazing and cooling.
    - Do not use oxyacetylene or gas shielded arc welding.
  good_for:
    - 'Bearings and bushings: Concast says the lead gives good lubricity and the alloy envelopes foreign matter.'
    - 'Machined parts: the machinability rating is 80 relative to free-cutting brass.'
    - 'Soldered joints: Concast rates soldering good.'
  watch_out:
    - 'Strength: the sources give 145 MPa minimum tensile strength (Concast, ICAST) and 185 MPa (AZoM), which are not the same basis.'
    - Brazing is rated poor and strain during brazing and cooling must be avoided.
    - No corrosion rate for C94300 was found in the sources read.
    - The composition ranges differ between AZoM and ICAST, and ICAST is used here.
  verdict: 'Leaded tin bronze C94300 (UNS C94300, high-leaded tin bronze) is a copper alloy with 23 to 27 % lead and 4.5 to 6 % tin. It is a soft bearing and machining alloy: the sources give 145 MPa minimum tensile strength and a machinability rating of 80. Brazing is rated poor and the lead carries the hazard statements. No corrosion rate and no EN number were found.'
  recipe:
    line: 'C94300 is a copper-tin-lead alloy: copper is the matrix, lead is the main addition that gives free cutting and bearing lubricity (Concast), and tin is the second alloying element. Phosphorus, zinc, iron, antimony, nickel plus cobalt and sulphur are limits, not deliberate additions, per the ICAST composition table. It is supplied as cast or continuously cast shapes.'
    parts:
      - name: Copper
        symbol: Cu
        share_percent: 67
        share_high: 72
        role: Matrix; the ICAST table gives copper 67 to 72 %
        source: icast-sb505
        where: Chemical Composition table, Cu % row
      - name: Lead
        symbol: Pb
        share_percent: 23
        share_high: 27
        role: Gives free cutting and lubricity (Concast)
        source: icast-sb505
        where: Chemical Composition table, Pb % row
      - name: Tin
        symbol: Sn
        share_percent: 4.5
        share_high: 6
        role: Second alloying element; the ICAST table gives tin 4.500 to 6.000 %
        source: icast-sb505
        where: Chemical Composition table, Sn % row
      - name: Phosphorus
        symbol: P
        share_percent: 1.5
        share_note: maximum
        role: Limit only
        source: icast-sb505
        where: Chemical Composition table, P % row, max
      - name: Zinc
        symbol: Zn
        share_percent: 0.8
        share_note: maximum
        role: Impurity limit
        source: icast-sb505
        where: Chemical Composition table, Zn % row, max
      - name: Iron
        symbol: Fe
        share_percent: 0.15
        share_note: maximum
        role: Impurity limit
        source: icast-sb505
        where: Chemical Composition table, Fe % row, max
      - name: Antimony
        symbol: Sb
        share_percent: 0.8
        share_note: maximum
        role: Limit only
        source: icast-sb505
        where: Chemical Composition table, Sb % row, max
      - name: Nickel plus cobalt
        symbol: Ni+Co
        share_percent: 1
        share_note: maximum
        role: Limit only
        source: icast-sb505
        where: Chemical Composition table, Ni + Co row, max
      - name: Sulphur
        symbol: S
        share_percent: 0.08
        share_note: maximum
        role: Limit only
        source: icast-sb505
        where: Chemical Composition table, S % row, max
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 23
  unreachable: 4
  caveats: 4
  note: 'Values were read by an AI assistant on 2026-11-01 from the pages and PDFs named in each entry. Unreachable: the copper.org alloy page (HTTP 403), the MakeItFrom page (HTTP 403), the MatWeb C94300 datasheet (HTTP 403) and the JMH Copper page (expired certificate). Caveats: the Concast and AZoM strengths, moduli and elongations disagree, the composition ranges differ between AZoM and ICAST, and the USGS tables were extracted with pdftotext.'
license: CC-BY-4.0