Copper Alloy C31400
UNS C31400 · ASTM B140
C31400 (also listed as B140) is a leaded commercial bronze, nominally 89Cu-9.5Zn-1.8Pb, in which the lead is added purely as a chip breaker for high-speed automatic screw-machine work.
Reference datasheet — C31400 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the H02 condition
C31400 tempers and conditions
C31400 is supplied in 5 conditions, soft to hard. H02 is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Soft annealed | Choose for maximum ductility when parts are cold headed, deep drawn, bent or heavily staked after forming. | 90 | 255 | 45 | 55 HB | 43 % IACS |
Quarter hard | Intermediate temper when moderate strength must be combined with some remaining bend ductility. | 195 | 305 | 28 | 85 HB | 43 % IACS |
H02Default Half hard | The standard stock temper for automatic screw-machine rod — best balance of chip control, straightness and strength. | 240 | 345 | 20 | 100 HB | 42 % IACS |
Full hard | Pick for maximum strength, stiffness in bending and wear resistance in threaded or spring-loaded hardware; little bend ductility left. | 340 | 415 | 10 | 125 HB | 41 % IACS |
Extra hard | Heavily cold-worked strip and wire where peak hardness and spring-back are wanted and no forming follows. | 400 | 455 | 6 | 140 HB | 41 % IACS |
What is C31400?
C31400 (also listed as B140) is a leaded commercial bronze, nominally 89Cu-9.5Zn-1.8Pb, in which the lead is added purely as a chip breaker for high-speed automatic screw-machine work. It is chosen for its machinability score of 80 (about 80 % of C36000) combined with 240 MPa yield, 345 MPa tensile, 20 % elongation, 42 % IACS conductivity and service to 200 °C, and is stocked as rod, bar and wire in O60 through H06. Lead makes it unsuitable for fusion welding and rules out hot working, so joints are soldered, brazed or mechanical. For lead-free turned hardware, C22600 forms better but machines far more slowly. C31400 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 1,010°C (1,850 °F). C31400 has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 345 MPa (50 ksi) — stronger than 52% of copper alloy grades. Elongation at break is 20% and the elastic modulus is 117 GPa (17 Msi).
What is C31400 used for?
- hinges
- screws
- hardware fittings
- builders' hardware
Advantages
- Easy to machine — 80/100, better than 86% of copper alloy grades
- Forms and bends easily — 70/100, better than 80% of copper alloy grades
- Conducts heat well — 180 W/m·K (104 BTU/hr·ft·°F), better than 75% of copper alloy grades
- High electrical conductivity — 42 % IACS, better than 75% of copper alloy grades
Limitations
- Difficult to weld — 25/100, worse than 78% of copper alloy grades
C31400 properties
Typical room-temperature values for C31400-H02; bars are the position among copper alloy grades.
Physical3
C31400 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 1,010°C (1,850 °F).
Mechanical12
C31400 has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 345 MPa (50 ksi) — stronger than 52% of copper alloy grades. Elongation at break is 20% and the elastic modulus is 117 GPa (17 Msi).
Thermal6
C31400 is rated for continuous service to 200°C (392 °F). It conducts heat at 180 W/m·K (104 BTU/hr·ft·°F), better than 75% of copper alloy grades. Thermal expansion is 18.4 µm/m·K (10.2 µin/in·°F).
Electrical3
C31400 conducts electricity at 42 % IACS, better than 75% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C31400 takes about 55 MJ of energy and emits 3.6 kg of CO₂ — less than 72% of copper alloy grades. Typical recycled content is 45%.
Manufacturability8
C31400's machinability is very good (80/100, better than 86% of copper alloy grades); weldability poor (25/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the copper alloy family
Yield strength against density for every copper alloy grade FabDigit runs. C31400 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C31400
Is C31400 easy to machine?
Excellent free-cutting behaviour (≈80% of C36000): use high positive rake carbide or HSS, 200–400 m/min, light oil or emulsion; lead gives short broken chips and long tool life.
Can C31400 be welded?
Not recommended for fusion welding (lead causes hot cracking); join by soft soldering or silver brazing, which it takes very well.
Can C31400 be formed, bent or molded?
Anneal to O60 for cold heading, drawing and severe bends; H02/H04 tempers are limited to gentle bends of 1–2 t radius.
C31400 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CuCu + named elements ≥ 99.5% | 87.5 – 90.5 | 89 |
| Pbfree-machining additive | 1.3 – 2.5 | 1.8 |
| Fe | ≤ 0.1 | |
| Zn | balance |
What surface finishes work on C31400?
Takes bright polishing, nickel/chrome, tin and gold plating readily; lacquer or benzotriazole treatment prevents tarnish — no anodizing.
Surface treatments FabDigit runs on copper alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Equivalent designations
Standards and trade names that resolve to Copper Alloy C31400 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- B140
How much does C31400 cost?
C31400 is a high-cost copper alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C31400 — frequently asked
What is C31400 used for?
C31400 is typically used for hinges, screws, hardware fittings and builders' hardware. In short: free-cutting commercial bronze; 80 % of C36000 machinability; not fusion weldable.
What is the yield strength of C31400?
C31400 has a typical yield strength of 240 MPa (34.8 ksi) and a tensile strength of 345 MPa (50 ksi) — stronger than 52% of copper alloy grades. Strength varies by condition: see the 5 listed tempers.
Is C31400 easy to machine?
Yes — machinability is rated very good (80/100, better than 86% of copper alloy grades). Excellent free-cutting behaviour (≈80% of C36000): use high positive rake carbide or HSS, 200–400 m/min, light oil or emulsion; lead gives short broken chips and long tool life.
Can C31400 be welded?
Not readily — weldability is rated poor (25/100). Not recommended for fusion welding (lead causes hot cracking); join by soft soldering or silver brazing, which it takes very well.
What surface finishes work on C31400?
Takes bright polishing, nickel/chrome, tin and gold plating readily; lacquer or benzotriazole treatment prevents tarnish — no anodizing.
Can C31400 be formed, bent or molded?
Anneal to O60 for cold heading, drawing and severe bends; H02/H04 tempers are limited to gentle bends of 1–2 t radius.
What is the maximum service temperature of C31400?
C31400 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C31400-H02 and C31400-H06?
H02 is the default condition — the standard stock temper for automatic screw-machine rod — best balance of chip control, straightness and strength. H06: heavily cold-worked strip and wire where peak hardness and spring-back are wanted and no forming follows. Yield strength is 240 MPa in H02 versus 400 MPa in H06.
How much does C31400 cost?
C31400 is a high-cost copper alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM B140/B140M — Copper-Zinc-Lead (Leaded Red Brass or Hardware Bronze) Rod, Bar and Shapes — ASTM International (2019)
- CDA/UNS C31400 alloy datasheet (copper.org Alloy Database) — Copper Development Association (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASTM B36/B36M — Brass Plate, Sheet, Strip and Rolled Bar — ASTM International (2018)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.