Technical Catalog
Silicon Bronze Fasteners
Alloy 651 / C65100 & C65500 Silicon Bronze Nuts, Bolts, and Screws Exporter
High Corrosion Stability in Marine, Seawater and High-Heat Environments
Product Overview
Kuldevi Forge & Fittings is a leading manufacturer and supplier of high-quality **Silicon Bronze Fasteners** (Alloy 651 / UNS C65100, C65500, and C65600). Composed of approximately 96% copper and 4% silicon, along with refined amounts of manganese, tin, zinc, and iron, these fasteners exhibit outstanding mechanical toughness, high yield strength, and superior resistance to acidic, chloride, and marine environments.
Silicon bronze fasteners are specifically favored in coastal, marine, and industrial seawater applications due to their exceptional pitting resistance. The addition of silicon increases the alloy's structural integrity, allowing it to withstand heavy loads and high pressure, while its high copper base offers natural anti-biofouling properties and excellent electrical conductivity.
Our comprehensive range includes metric and imperial Silicon Bronze Hex Bolts, Machine Screws, Carriage Bolts, Studs, Threaded Rods, Hex Nuts, and Washers manufactured under precise tolerances to match the highest international standards.
Standard Specifications
| Fasteners Standard | UNS C65500, C65100, C65600, and all international standards |
|---|---|
| Material Specifications | ASME SB584 / ASTM B584 Silicon Bronze |
| ASTM Specification | ASTM F467 | ASTM B98 | ASTM F468 | ASTM B96 | ASTM B99 |
| Sizes Range | 3/16″ to 2″ | M02 to M30 | Custom sizes as per drawings |
| Length Standards | 3 mm to 200 mm |
| Thread Configurations | UNF, UNC, BSW, ISO, ACME, and Metric Coarse/Fine |
| Dimension Standards | BS, ASME, ISO, DIN, DIN-EN, UNI |
| Available Types | Hex Bolts, Hex Nuts, Carriage Bolts, Stud Bolts, Threaded Rods, Machine Screws, Phillips CSK Flat Screws, Flat Washers, Lock Washers, Sems Bolts, Hex Lag Bolts |
Equivalent Grades
| Alloy Designation | UNS Number | EN Standard | DIN / BS Equivalent |
|---|---|---|---|
| CDA 655 | UNS C65500 | EN CW116C | DIN 2.1525 / BS CS101 |
| CDA 651 | UNS C65100 | EN CW115C | Chemical CuSi2 |
Chemical Composition
| Element | Composition Limits (%) |
|---|---|
| Silicon (Si) | 2.80 - 3.80% |
| Manganese (Mn) | 0.50 - 1.30% |
| Zinc (Zn) | 1.50% Max |
| Iron (Fe) | 0.80% Max |
| Copper (Cu) | Remaining (Balance) |
Mechanical Properties (Up to 2″ Diameter)
| Mechanical Parameter | Design Limits / Value |
|---|---|
| Ultimate Tensile Strength (UTS) | 485 N/mm² (Minimum) |
| 0.2% Proof Strength (Yield Strength) | 260 N/mm² (Minimum) |
| Elongation in 2" (50mm) | 20% (Minimum) |
| Hardness Range | 75 - 95 HRB |
CDA 651 Silicon Bronze Nuts Height Chart (Metric)
Nut thicknesses across different hex forms. Diameter values denote width across flats.
| Nut Size (mm) | Diameter* (mm) | Hex Nut Height (mm) | Jam Nut Height (mm) | Nylock Nut Height (mm) |
|---|---|---|---|---|
| M2 | 4.0 | 1.6 | 1.2 | – |
| M2.5 | 5.0 | 2.0 | 1.6 | – |
| M3 | 5.5 | 2.4 | 1.8 | 4.0 |
| M4 | 7.0 | 3.2 | 2.2 | 5.0 |
| M5 | 8.0 | 4.0 | 2.7 | 5.0 |
| M6 | 10.0 | 5.0 | 3.2 | 6.0 |
| M7 | 11.0 | 5.5 | 3.5 | – |
| M8 | 13.0 | 6.5 | 4.0 | 8.0 |
| M10 | 17.0 | 8.0 | 5.0 | 10.0 |
| M12 | 19.0 | 10.0 | 6.0 | 12.0 |
| M14 | 22.0 | 11.0 | 7.0 | 14.0 |
| M16 | 24.0 | 13.0 | 8.0 | 16.0 |
| M18 | 27.0 | 15.0 | 9.0 | 18.5 |
| M20 | 30.0 | 16.0 | 10.0 | 20.0 |
* Wrench size corresponds to the basic width across flats diameter.
UNS C65100 Hex Bolt Dimensions (Metric)
All dimensions in millimeters as per standards specifications.
| Nominal Size (D) | Body Diameter (D) | Head Thickness (H) | Width Across Flats (F) | Width Across Corners (C) | ||||
|---|---|---|---|---|---|---|---|---|
| Max | Min | Max | Min | Max | Min | Max | Min | |
| M10 | 10.00 | 9.78 | 6.63 | 6.17 | 17.00 | 15.73 | 18.48 | 17.77 |
| M12 | 12.00 | 11.73 | 7.76 | 4.24 | 19.00 | 17.73 | 20.78 | 20.03 |
| M14 | 14.00 | 13.73 | 9.09 | 8.51 | 22.00 | 20.67 | 24.25 | 23.35 |
| M16 | 16.00 | 15.73 | 10.32 | 9.68 | 24.00 | 23.67 | 27.71 | 26.75 |
| M20 | 20.00 | 19.67 | 12.88 | 12.12 | 30.00 | 29.16 | 34.64 | 32.95 |
| M24 | 24.00 | 23.67 | 15.44 | 14.56 | 36.00 | 35.00 | 41.57 | 39.55 |
| M30 | 30.00 | 29.67 | 19.48 | 17.92 | 46.00 | 45.00 | 53.12 | 50.85 |
| M36 | 36.00 | 35.61 | 23.38 | 21.63 | 55.00 | 53.80 | 63.51 | 60.79 |
| M42 | 42.00 | 41.38 | 26.97 | 25.03 | 65.00 | 62.90 | 75.06 | 71.71 |
| M48 | 48.00 | 47.38 | 31.07 | 28.93 | 75.00 | 72.60 | 86.60 | 82.76 |
| M56 | 56.00 | 55.26 | 36.20 | 33.80 | 85.00 | 82.20 | 98.15 | 93.71 |
| M64 | 64.00 | 63.26 | 41.32 | 38.68 | 95.00 | 91.80 | 109.70 | 104.65 |
| M72 | 72.00 | 71.26 | 46.45 | 43.55 | 105.00 | 101.40 | 121.24 | 115.60 |
| M80 | 80.00 | 79.26 | 51.58 | 48.42 | 115.00 | 111.00 | 132.72 | 126.54 |
| M90 | 90.00 | 89.13 | 57.74 | 54.26 | 130.00 | 125.50 | 150.11 | 143.07 |
| M100 | 90.00 | 99.13 | 63.90 | 60.10 | 145.00 | 140.00 | 167.43 | 159.60 |
Silicon Bronze Hex Nuts Dimensions Table (Imperial)
Width across flats (F), width across corners (G), and thickness (H) in inches.
| Nominal Size | Basic Thread Dia | Width Across Flats (F) | Width Across Corners (G) | Thickness (H) | |||||
|---|---|---|---|---|---|---|---|---|---|
| Basic | Max | Min | Max | Min | Basic | Max | Min | ||
| 1/4″ | 0.2500 | 7/16 | 0.438 | 0.428 | 0.505 | 0.488 | 7/32 | 0.226 | 0.212 |
| 5/16″ | 0.3125 | 1/2 | 0.500 | 0.489 | 0.577 | 0.557 | 17/64 | 0.273 | 0.258 |
| 3/8″ | 0.3750 | 9/16 | 0.562 | 0.551 | 0.650 | 0.628 | 21/64 | 0.337 | 0.479 |
| 7/16″ | 0.4375 | 11/16 | 0.688 | 0.675 | 0.794 | 0.768 | 3/8 | 0.385 | 0.365 |
| 1/2″ | 0.5000 | 3/4 | 0.750 | 0.736 | 0.866 | 0.840 | 7/16 | 0.448 | 0.427 |
| 9/16″ | 0.5625 | 7/8 | 0.875 | 0.861 | 1.010 | 0.982 | 31/64 | 0.496 | 0.473 |
| 5/8″ | 0.6250 | 15/16 | 0.938 | 0.922 | 1.083 | 1.051 | 35/64 | 0.559 | 0.535 |
| 3/4″ | 0.7500 | 1-1/8 | 1.125 | 1.088 | 1.299 | 1.240 | 41/64 | 0.665 | 0.617 |
| 7/8″ | 0.8750 | 1-5/16 | 1.312 | 1.269 | 1.516 | 1.447 | 3/4 | 0.776 | 0.724 |
| 1″ | 1.0000 | 1-1/2 | 1.500 | 1.450 | 1.732 | 1.653 | 55/64 | 0.887 | 0.831 |
| 1-1/8″ | 1.1250 | 1-11/16 | 1.688 | 1.631 | 1.949 | 1.859 | 31/32 | 0.999 | 0.939 |
| 1-3/8″ | 1.3750 | 2-1/16 | 2.062 | 1.994 | 2.382 | 2.273 | 1-11/64 | 1.206 | 1.138 |
| 1-1/2″ | 1.5000 | 2-1/4 | 2.250 | 2.175 | 2.598 | 2.480 | 1-9/32 | 1.312 | 1.245 |
| 1-5/8″ | 1.6250 | 2-7/16 | 2.438 | 2.356 | 2.815 | 2.686 | 1-25/64 | 1.429 | 1.353 |
| 1-3/4″ | 1.7500 | 2-5/8 | 2.625 | 2.538 | 3.031 | 2.893 | 1-1/2 | 1.540 | 1.460 |
| 2″ | 2.0000 | 3 | 3.000 | 2.900 | 3.464 | 3.306 | 1-23/32 | 1.763 | 1.675 |
| 2-1/4″ | 2.2500 | 3-3/8 | 3.375 | 3.263 | 3.897 | 3.719 | 1-15/16 | 1.986 | 1.890 |
| 2-1/2″ | 2.5000 | 3-3/4 | 3.750 | 3.625 | 4.330 | 4.133 | 2-5/32 | 2.209 | 2.105 |
| 2-3/4″ | 2.7500 | 4-1/8 | 4.125 | 3.988 | 4.763 | 4.546 | 2-3/8 | 2.431 | 2.319 |
Silicon Bronze Wood Screws Dimensions
Shank and root diameters in inches, including threads per inch specifications.
| Screw Number | Max. Head Dia | Shank Diameter | Root Diameter | Threads Per Inch | ||
|---|---|---|---|---|---|---|
| Basic Decimal | Nearest Fraction | Avg Decimal | Nearest Fraction | |||
| 0 | 0.119 | 0.060 | 1/16 | 0.040 | 3/64 | 32.00 |
| 1 | 0.146 | 0.073 | 5/64 | 0.046 | 3/64 | 28.00 |
| 2 | 0.172 | 0.086 | 3/32 | 0.054 | 1/16 | 26.00 |
| 3 | 0.199 | 0.099 | 7/64 | 0.065 | 1/16 | 24.00 |
| 4 | 0.225 | 0.112 | 7/64 | 0.075 | 5/64 | 22.00 |
| 5 | 0.252 | 0.125 | 1/8 | 0.085 | 5/64 | 20.00 |
| 6 | 0.279 | 0.138 | 9/64 | 0.094 | 3/32 | 18.00 |
| 7 | 0.305 | 0.151 | 5/32 | 0.102 | 7/64 | 16.00 |
| 8 | 0.332 | 0.164 | 5/32 | 0.112 | 7/64 | 15.00 |
| 9 | 0.358 | 0.177 | 11/64 | 0.122 | 1/8 | 14.00 |
| 10 | 0.385 | 0.190 | 3/16 | 0.130 | 1/8 | 13.00 |
| 11 | 0.411 | 0.203 | 13/64 | 0.139 | 9/64 | 12.00 |
| 12 | 0.438 | 0.216 | 7/32 | 0.148 | 9/64 | 11.00 |
| 14 | 0.491 | 0.242 | 1/4 | 0.165 | 5/32 | 10.00 |
| 16 | 0.544 | 0.268 | 17/64 | 0.184 | 3/16 | 9.00 |
| 18 | 0.597 | 0.294 | 19/64 | 0.204 | 13/64 | 8.00 |
| 20 | 0.650 | 0.320 | 5/16 | 0.233 | 7/32 | 8.00 |
| 24 | 0.756 | 0.372 | 3/8 | 0.260 | 1/4 | 7.00 |
Silicon Bronze Flat Washer Dimensions Chart
Outer Diameter (OD), Inner Diameter (ID), and Thickness in inches for USS and SAE classifications.
| Bolt Size | USS Standard | SAE Standard | ||||
|---|---|---|---|---|---|---|
| OD (in.) | ID (in.) | Thickness (in.) | OD (in.) | ID (in.) | Thickness (in.) | |
| 1/8″ (#6) | – | – | – | 0.375 | 0.156 | .036/.065 |
| 5/32″ (#8) | – | – | – | 0.438 | 0.188 | .036/.065 |
| 3/16″ (#10) | 0.560 | 0.250 | .036/.065 | 0.500 | 0.220 | .036/.065 |
| 7/32″ (#12) | – | – | – | 0.562 | 0.250 | .051/.080 |
| 1/4″ (#14) | 0.734 | 0.312 | .051/.080 | 0.625 | 0.281 | .051/.080 |
| 5/16″ | 0.875 | 0.375 | .064/.104 | 0.688 | 0.344 | .051/.080 |
| 3/8″ | 1.000 | 0.438 | .064/.104 | 0.812 | 0.406 | .051/.080 |
| 7/16″ | 1.250 | 0.500 | .064/.104 | 0.922 | 0.469 | .051/.080 |
| 1/2″ | 1.375 | 0.562 | .086/.132 | 1.062 | 0.531 | .074/.121 |
| 9/16″ | 1.469 | 0.625 | .086/.132 | 1.156 | 0.594 | .074/.121 |
| 5/8″ | 1.750 | 0.688 | .108/.160 | 1.312 | 0.656 | .074/.121 |
| 3/4″ | 2.000 | 0.812 | .122/.177 | 1.469 | 0.812 | .108/.160 |
| 7/8″ | 2.250 | 0.938 | .136/.192 | 1.750 | 0.938 | .108/.160 |
| 1″ | 2.500 | 1.062 | .136/.192 | 2.000 | 1.062 | .108/.160 |
| 1-1/8″ | 2.750 | 1.250 | .136/.192 | 2.250 | 1.250 | .108/.160 |
| 1-1/4″ | 3.000 | 1.375 | .136/.192 | 2.500 | 1.375 | .136/.192 |
| 1-3/8″ | 3.250 | 1.500 | .153/.213 | 2.750 | 1.500 | .136/.213 |
| 1-1/2″ | 3.500 | 1.625 | .153/.213 | 3.000 | 1.625 | .153/.213 |
| 1-5/8″ | 3.750 | 1.750 | .153/.213 | – | – | – |
| 1-3/4″ | 4.000 | 1.875 | .153/.213 | – | – | – |
| 1-7/8″ | 4.250 | 2.000 | .153/.213 | – | – | – |
| 2″ | 4.500 | 2.125 | .153/.213 | – | – | – |
| 2-1/4″ | 4.750 | 2.375 | .320/.248 | – | – | – |
| 2-1/2″ | 5.000 | 2.625 | .210/.280 | – | – | – |
| 2-3/4″ | 5.250 | 2.875 | .228/.410S | – | – | – |
| 3″ | 5.500 | 3.125 | .249/.327 | – | – | – |
Socket Head Cap Screw Dimensions Schedule
Nominal sizes M3 to M24 with thread pitch, socket sizing, body diameter, and head diameters in mm.
| Nominal Size | Thread Pitch | Hex Socket Size (J) | Body Diameter & Head Height (D/H) | Head Diameter (A) | Socket Length (K) | ||
|---|---|---|---|---|---|---|---|
| Max | Min | Max | Min | ||||
| M3 | 0.50 | 2.50 | 3.00 | 2.86 | 5.50 | 5.20 | 1.3 |
| M4 | 0.70 | 3.00 | 4.00 | 3.82 | 7.00 | 6.64 | 2.0 |
| M5 | 0.80 | 4.00 | 5.00 | 4.82 | 8.50 | 8.14 | 2.7 |
| M6 | 1.00 | 5.00 | 6.00 | 5.82 | 10.00 | 9.64 | 3.3 |
| M8 | 1.25 | 6.00 | 8.00 | 7.78 | 13.00 | 12.57 | 4.3 |
| M10 | 1.50 | 8.00 | 10.00 | 9.78 | 16.00 | 15.57 | 5.5 |
| M12 | 1.75 | 10.00 | 12.00 | 11.73 | 18.00 | 17.57 | 6.6 |
| M16 | 2.00 | 14.00 | 16.00 | 15.73 | 24.00 | 23.48 | 8.8 |
| M20 | 2.50 | 17.00 | 20.00 | 19.67 | 30.00 | 29.48 | 10.7 |
| M24 | 3.00 | 19.00 | 24.00 | 23.67 | 36.00 | 35.38 | 12.9 |
Tightening Torque Chart (Electrical Applications)
Target torque values (in-lbs) for Silicon Bronze bolts compared to Stainless Steel and other alloy systems.
| Bolt Size | Silicon Bronze (in-lbs) | 18-8 Stainless (in-lbs) | 316 Stainless (in-lbs) | Monel Alloy (in-lbs) | Brass Alloy (in-lbs) | 2024-T4 Al Alloy (in-lbs) |
|---|---|---|---|---|---|---|
| 4-40 | 4.8 | 5.2 | 5.5 | 5.3 | 4.3 | 2.9 |
| 4-48 | 6.1 | 6.6 | 6.9 | 6.7 | 5.4 | 3.6 |
| 5-40 | 7.1 | 7.7 | 8.1 | 7.8 | 6.3 | 4.2 |
| 5-44 | 8.7 | 9.4 | 9.8 | 9.6 | 7.7 | 5.1 |
| 6-32 | 8.9 | 9.6 | 10.1 | 9.8 | 7.9 | 5.3 |
| 6-40 | 11.2 | 12.1 | 12.7 | 12.3 | 9.9 | 6.6 |
| 8-32 | 18.4 | 19.8 | 20.7 | 20.2 | 16.2 | 10.8 |
| 8-36 | 20.4 | 22.0 | 23.0 | 22.4 | 18.0 | 12.0 |
| 10-24 | 21.2 | 22.8 | 23.8 | 25.9 | 18.6 | 13.8 |
| 10-32 | 29.3 | 31.7 | 33.1 | 34.9 | 25.9 | 19.2 |
| 1/4-20 | 68.8 | 75.2 | 78.8 | 85.3 | 61.5 | 45.6 |
| 1/4-28 | 87.0 | 94.0 | 99.0 | 106.0 | 77.0 | 57.0 |
| 5/16-18 | 123.0 | 132.0 | 138.0 | 149.0 | 107.0 | 80.0 |
| 5/16-24 | 131.0 | 142.0 | 147.0 | 160.0 | 116.0 | 86.0 |
| 3/8-16 | 219.0 | 236.0 | 247.0 | 266.0 | 192.0 | 143.0 |
| 3/8-24 | 240.0 | 259.0 | 271.0 | 294.0 | 212.0 | 157.0 |
| 7/16-14 | 349.0 | 376.0 | 393.0 | 427.0 | 317.0 | 228.0 |
| 7/16-20 | 371.0 | 400.0 | 418.0 | 451.0 | 327.0 | 242.0 |
| 1/2-13 | 40.0* | 43.0* | 45.0* | 48.7* | 35.2* | 26.0* |
| 1/2-20 | 42.0* | 45.0* | 47.0* | 51.0* | 37.0* | 27.0* |
| 9/16-12 | 53.0* | 56.0* | 59.0* | 65.0* | 47.0* | 34.0* |
| 9/16-18 | 58.0* | 62.0* | 65.0* | 71.0* | 51.0* | 38.0* |
| 5/8-11 | 86.0* | 92.0* | 96.0* | 111.0* | 76.0* | 60.0* |
| 5/8-18 | 96.0* | 103.0* | 108.0* | 123.0* | 85.0* | 67.0* |
| 3/4-10 | 118.0* | 127.0* | 131.0* | 153.0* | 104.0* | 82.0* |
| 3/4-16 | 115.0* | 124.0* | 129.0* | 149.0* | 102.0* | 80.0* |
| 7/8-9 | 178.0* | 194.0* | 202.0* | 231.0* | 159.0* | 124.0* |
| 7/8-14 | 177.0* | 193.0* | 201.0* | 230.0* | 158.0* | 124.0* |
| 1-8 | 265.0* | 286.0* | 299.0* | 344.0* | 235.0* | 184.0* |
| 1-14 | 240.0* | 259.0* | 270.0* | 311.0* | 212.0* | 166.0* |
* Values marked with an asterisk are in ft-lbs, all other values are in in-lbs.
Technical Features
- High Seawater Resistance: Outstanding stability against brackish water and salt corrosion.
- Non-Sparking Properties: Ideal for non-sparking safety environments (oil platforms, safety valves).
- Elevated Melting Point: Superior thermal stability compared to general brasses.
- Structural Strength: High fatigue limits, toughness, and load capacities.
Industry Applications
- Offshore Marine hardware & shipbuilding
- Sea water intake piping & condenser equipment
- Chemical & Pharmaceutical process lines
- Electrical groundings & switchgears
- Power generation plants & heat exchangers