Copper Alloy C91100-M04
Finish state
UNS C91100
M04 = as pressure die cast
Used for smaller repeat parts where mould-chilled fine structure and better surface are wanted.
Values for the M04 condition
Other C91100 tempers and conditions
C91100 is listed in 4 conditions; see the grade overview at C91100.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
M01Default As sand cast | Standard as-cast sand-mould condition for worm gear rims, bearing blanks and bridge plates. | 172 | 241 | 2 | 135 HB | 8 % IACS |
M04This page As pressure die cast | Used for smaller repeat parts where mould-chilled fine structure and better surface are wanted. | 180 | 255 | 2 | 140 HB | 8 % IACS |
As centrifugally cast | Choose for rings, bushings and gear blanks needing sounder, finer structure than sand casting. | 186 | 262 | 2 | 140 HB | 8 % IACS |
As continuous cast | Continuous-cast bar/tube stock for machined bushings and worm gears; densest and most uniform product form. | 193 | 275 | 2 | 145 HB | 8 % IACS |
What is C91100-M04?
C91100-M04 is C91100 supplied in the M04 condition — used for smaller repeat parts where mould-chilled fine structure and better surface are wanted. C91100-M04 has a yield strength of 180 MPa (26.1 ksi) and a tensile strength of 255 MPa (37 ksi) — weaker than 59% of copper alloy grades. Elongation at break is 2% and the elastic modulus is 103 GPa (14.9 Msi). C91100-M04 has a density of 8.6 g/cm³ (0.311 lb/in³), lighter than 59% of copper alloy grades. It melts at 830°C (1,526 °F). M01 is the default condition FabDigit quotes; M04 is available on request or by drawing note.
Advantages
- High service temperature — 260°C (500 °F), better than 75% of copper alloy grades
Limitations
- Limited ductility — 2%, worse than 98% of copper alloy grades
- Limited formability — 5/100, worse than 98% of copper alloy grades
- Difficult to weld — 15/100, worse than 94% of copper alloy grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 91% of copper alloy grades
- Poor heat conductor — 37 W/m·K (21.4 BTU/hr·ft·°F), worse than 85% of copper alloy grades
C91100-M04 properties
Typical room-temperature values for C91100-M04; 21 are specific to this condition. Other listed values are C91100 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C91100-M04 has a density of 8.6 g/cm³ (0.311 lb/in³), lighter than 59% of copper alloy grades. It melts at 830°C (1,526 °F).
Mechanical15
C91100-M04 has a yield strength of 180 MPa (26.1 ksi) and a tensile strength of 255 MPa (37 ksi) — weaker than 59% of copper alloy grades. Elongation at break is 2% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal5
C91100-M04 is rated for continuous service to 260°C (500 °F). It conducts heat at 37 W/m·K (21.4 BTU/hr·ft·°F), worse than 85% of copper alloy grades. Thermal expansion is 16.6 µm/m·K (9.22 µin/in·°F).
Electrical3
C91100-M04 conducts electricity at 8 % IACS, worse than 81% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 68% of copper alloy grades.
Sustainability4
Producing a kilogram of C91100-M04 takes about 87 MJ of energy and emits 5.6 kg of CO₂ — more than 92% of copper alloy grades. Typical recycled content is 40%.
Manufacturability7
C91100-M04's machinability is fair (45/100, better than 64% of copper alloy grades); weldability poor (15/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C91100-M04
Is C91100 easy to machine?
Machines with short brittle chips; use sharp positive-rake carbide, rigid setup, light feeds and generous coolant — hard δ-phase abrades tooling and edges chip easily.
Can C91100 be welded?
Fusion welding is not recommended (hot-short, crack-prone); repair by brazing or soldering, or by low-heat braze-welding with matching tin-bronze rod.
Can C91100 be formed, bent or molded?
Cast product only — no cold or hot working; design generous risers and directional solidification to avoid tin sweat and interdendritic shrinkage.
What surface finishes work on C91100?
Takes a good buffed or lapped finish; can be tin, nickel or chrome plated after cleaning, and gear/bearing surfaces are usually finish-ground or honed rather than coated.
C91100 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Sn | 15 – 17 | 16 |
| Pdeoxidizer; raises hardness | ≤ 1 | 0.3 |
| Ni | ≤ 0.5 | — |
| Pb | ≤ 0.25 | — |
| Zn | ≤ 0.25 | — |
| Fe | ≤ 0.25 | — |
| Sb | ≤ 0.2 | — |
| S | ≤ 0.05 | — |
| Al | ≤ 0.01 | — |
| Si | ≤ 0.01 | — |
| Cu | ≥ 82 (balance) | — |
C91100-M04 — frequently asked
What is C91100-M04 used for?
C91100-M04 is typically used for worm gear rims for slow-speed drives, gear wheels, heavily loaded bearing bushings, wear plates and slide guides, thrust washers and machine tool nuts and screw threads. In short: hardest plain tin bronze; cast worm-gear standard; very low ductility.
What is the yield strength of C91100-M04?
C91100-M04 has a typical yield strength of 180 MPa (26.1 ksi) and a tensile strength of 255 MPa (37 ksi) — weaker than 59% of copper alloy grades. Strength varies by condition: see the 4 listed tempers.
Is C91100-M04 easy to machine?
Reasonably — machinability is rated fair (45/100, better than 64% of copper alloy grades). Machines with short brittle chips; use sharp positive-rake carbide, rigid setup, light feeds and generous coolant — hard δ-phase abrades tooling and edges chip easily.
Can C91100-M04 be welded?
Not readily — weldability is rated poor (15/100). Fusion welding is not recommended (hot-short, crack-prone); repair by brazing or soldering, or by low-heat braze-welding with matching tin-bronze rod.
What surface finishes work on C91100-M04?
Takes a good buffed or lapped finish; can be tin, nickel or chrome plated after cleaning, and gear/bearing surfaces are usually finish-ground or honed rather than coated.
Can C91100-M04 be formed, bent or molded?
Cast product only — no cold or hot working; design generous risers and directional solidification to avoid tin sweat and interdendritic shrinkage.
What is the maximum service temperature of C91100-M04?
C91100-M04 is rated for continuous use to about 260°C (500 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C91100-M01 and C91100-M07?
M01 is the default condition — standard as-cast sand-mould condition for worm gear rims, bearing blanks and bridge plates. M07: continuous-cast bar/tube stock for machined bushings and worm gears; densest and most uniform product form. Yield strength is 172 MPa in M01 versus 193 MPa in M07.
Sources
- ASTM B22 — Bronze Castings for Bridges and Turntables — ASTM International (2017)
- ASTM B505/B505M — Continuous-Cast Copper Alloy Castings — ASTM International (2018)
- CDA Copper Alloy Datasheet C91100 — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol.18 — Friction, Lubrication and Wear Technology — ASM International (2017)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.