Copper Alloy C91700
UNS C91700
C91700 is a higher-nickel tin bronze casting alloy in the C90000–C95999 family, developed for heavy-duty worm gearing where hardness and toughness must be combined.
Reference datasheet — C91700 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 M01 condition
C91700 tempers and conditions
C91700 is supplied in 4 conditions, soft to hard. M01 is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
M01Default As sand cast | Standard condition for gear rims, worm wheels and housings poured in sand moulds; most widely stocked/produced form. | 172 | 310 | 12 | 95 HB | 9 % IACS |
As plaster cast | Permanent-mold pouring for repeat-run small gear blanks and bushings; finer structure and better surface than sand casting. | 190 | 325 | 10 | 100 HB | 9 % IACS |
As centrifugally cast | Choose for worm-wheel rims, bushings and rings where a dense, porosity-free wall and higher strength are required. | 193 | 331 | 10 | 100 HB | 9 % IACS |
As continuous cast | Continuous-cast bar/tube stock for machined gear blanks and bearings; finest grain and highest as-cast strength, slightly lower ductility. | 207 | 345 | 8 | 105 HB | 9 % IACS |
What is C91700?
C91700 is a higher-nickel tin bronze casting alloy in the C90000–C95999 family, developed for heavy-duty worm gearing where hardness and toughness must be combined. Typical values are 310 MPa tensile, 172 MPa yield, 12 % elongation and 95 HB, supplied as sand, permanent-mold, centrifugal and continuous castings. Machinability is about 20 % of free-cutting brass, the alloy is not arc-weldable for structural joints, and the long freezing range requires careful risering to keep sections sound. C91600 is the closest alternative with a similar property set. C91700 has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 58% of copper alloy grades. It melts at 854°C (1,569 °F). C91700 has a yield strength of 172 MPa (24.9 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 60% of copper alloy grades. Elongation at break is 12% and the elastic modulus is 105 GPa (15.2 Msi).
What is C91700 used for?
- Heavy-duty worm gears
- Worm wheel rims
- Gear blanks
- High-load bearing bushings
- Wear rings and wear pads
- Thrust bearings for slow-speed drives
Advantages
- High service temperature — 260°C (500 °F), better than 75% of copper alloy grades
Limitations
- Low electrical conductivity — 9 % IACS, worse than 78% of copper alloy grades
- Difficult to weld — 25/100, worse than 78% of copper alloy grades
C91700 properties
Typical room-temperature values for C91700-M01; bars are the position among copper alloy grades.
Physical3
C91700 has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 58% of copper alloy grades. It melts at 854°C (1,569 °F).
Mechanical15
C91700 has a yield strength of 172 MPa (24.9 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 60% of copper alloy grades. Elongation at break is 12% and the elastic modulus is 105 GPa (15.2 Msi).
Thermal6
C91700 is rated for continuous service to 260°C (500 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), worse than 69% of copper alloy grades. Thermal expansion is 18 µm/m·K (10 µin/in·°F).
Electrical3
C91700 conducts electricity at 9 % IACS, worse than 78% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C91700 takes about 62 MJ of energy and emits 4.2 kg of CO₂ — more than 76% of copper alloy grades. Typical recycled content is 40%.
Manufacturability7
C91700's machinability is fair (35/100, better than 51% of copper alloy grades); weldability poor (25/100).
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. C91700 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C91700
Is C91700 easy to machine?
Machinability ≈20 % of free-cutting brass — take positive-rake sharp carbide tooling, moderate speed with generous coolant; gummy chips and hard tin-rich phases cause built-up edge.
Can C91700 be welded?
Essentially not arc-weldable for structural joints; repair only by low-heat braze or tin-bronze TIG with preheat and slow cool, expect hot-shortness and porosity.
Can C91700 be formed, bent or molded?
Casting alloy only, no cold forming; long freezing range demands chills, generous risers and directional solidification to avoid tin sweat and interdendritic shrinkage.
C91700 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 | 11.3 – 12.5 | 12 |
| NiNi + Co | 1.2 – 2 | 1.6 |
| Pb | ≤ 0.25 | |
| Zn | ≤ 0.25 | |
| Fe | ≤ 0.15 | |
| Sb | ≤ 0.2 | |
| Pmax (deoxidiser) | ≤ 0.3 | |
| S | ≤ 0.05 | |
| Al | ≤ 0.01 | |
| Si | ≤ 0.01 | |
| Cu | ≥ 84.5 (balance) |
What surface finishes work on C91700?
Cannot be anodised; finish by machining/grinding, polishing, chemical patination, or tin/nickel electroplating; lacquer to prevent tarnish in display parts.
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).
How much does C91700 cost?
C91700 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.
C91700 — frequently asked
What is C91700 used for?
C91700 is typically used for heavy-duty worm gears, worm wheel rims, gear blanks, high-load bearing bushings, wear rings and wear pads and thrust bearings for slow-speed drives. In short: high-nickel gear bronze; most ductile tin gear bronze; cast-only, hard to machine.
What is the yield strength of C91700?
C91700 has a typical yield strength of 172 MPa (24.9 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 60% of copper alloy grades. Strength varies by condition: see the 4 listed tempers.
Is C91700 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of copper alloy grades). Machinability ≈20 % of free-cutting brass — take positive-rake sharp carbide tooling, moderate speed with generous coolant; gummy chips and hard tin-rich phases cause built-up edge.
Can C91700 be welded?
Not readily — weldability is rated poor (25/100). Essentially not arc-weldable for structural joints; repair only by low-heat braze or tin-bronze TIG with preheat and slow cool, expect hot-shortness and porosity.
What surface finishes work on C91700?
Cannot be anodised; finish by machining/grinding, polishing, chemical patination, or tin/nickel electroplating; lacquer to prevent tarnish in display parts.
Can C91700 be formed, bent or molded?
Casting alloy only, no cold forming; long freezing range demands chills, generous risers and directional solidification to avoid tin sweat and interdendritic shrinkage.
What is the maximum service temperature of C91700?
C91700 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 C91700-M01 and C91700-M07?
M01 is the default condition — standard condition for gear rims, worm wheels and housings poured in sand moulds; most widely stocked/produced form. M07: continuous-cast bar/tube stock for machined gear blanks and bearings; finest grain and highest as-cast strength, slightly lower ductility. Yield strength is 172 MPa in M01 versus 207 MPa in M07.
How much does C91700 cost?
C91700 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 B427 — Gear Bronze Alloy Castings — ASTM International (2020)
- ASTM B505/B505M — Continuous Cast Copper Alloy Castings — ASTM International (2018)
- CDA Alloy Database — C91700 — Copper Development Association (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- GB/T 1176 (ZCuSn12Ni2) — SAC (2013)
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.