Silicon bronze alloy nuts with superior corrosion resistance and durability.
ASTM F467/F467M Grade C66100 Alloy 661 Nuts are widely used in marine and architectural applications because of their excellent resistance to seawater corrosion.
| UNS Designation Number | Alloy | General Name | Al | Cu, min | Fe, max | Mn, max | Ni, max | P | Si | Zn, max A | Pb, max | Tin | As, max |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ASTM F467/F467M Grade C66100 | 661 | silicon bronze | . . . | 94.0 D | 0.25 | 1.5 | . . . | . . . | 2.8-3.5 | 1.5 | 0.20-0.8 | . . . | . . . |
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| Alloy | Mechanical Property Marking | Hardness, min A | Proof Stress, Hex Nut min, ksi | Proof Stress, Heavy Hex Nut min, ksi B |
|---|---|---|---|---|
| ASTM F467 Alloy Cu 661 | F 467M | 75 HRB | 50 | 54 |
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| Alloy | Mechanical Property Marking | Hardness, min A | Proof Stress, Mpa |
|---|---|---|---|
| ASTM F467M Cu 661 | F467MM | 75 HRB | 345 |
| Nominal Size, in. | Coarse Threads-UNC | Fine Threads-UNF | 8 Thread Series-8UN | |||
|---|---|---|---|---|---|---|
| Threads/in. | Stress Area A, in 2 | Threads/in. | Stress Area A, in 2 | Threads/in. | Stress Area A, in 2 | |
| 1/ 4 | 20 | 0.0318 | 28 | 0.0364 | . . . | . . . |
| 5/ 16 | 18 | 0.0524 | 24 | 0.0580 | . . . | . . . |
| 3/ 8 | 16 | 0.0775 | 24 | 0.0878 | . . . | . . . |
| 7/ 16 | 14 | 0.1063 | 20 | 0.1187 | . . . | . . . |
| 1/ 2 | 13 | 0.1419 | 20 | 0.1599 | . . . | . . . |
| 9/ 16 | 12 | 0.1820 | 18 | 0.2030 | . . . | . . . |
| 5/ 8 | 11 | 0.2260 | 18 | 0.2560 | . . . | . . . |
| 3/ 4 | 10 | 0.3340 | 16 | 0.3730 | . . . | . . . |
| 7/ 8 | 9 | 0.4620 | 14 | 0.5090 | . . . | . . . |
| 1 | 8 | 0.6060 | 12 | 0.6630 | . . . | . . . |
| 1 1/ 8 | 7 | 0.7630 | 12 | 0.8560 | 8 | 0.790 |
| 1 1/ 4 | 7 | 0.9690 | 12 | 1.0730 | 8 | 1.000 |
| 1 3/ 8 | 6 | 1.1550 | 12 | 1.3150 | 8 | 1.233 |
| 1 1/ 2 | 6 | 1.4050 | 12 | 1.5810 | 8 | 1.492 |
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| Nominal Nut Diameter and Thread Pitch | Stress Area, Amm 2 | Nominal Nut Diameter and Thread Pitch | Stress Area, Amm 2 |
|---|---|---|---|
| M6 × 1 | 20.1 | M16 × 2 | 157 |
| M8 × 1.25 | 36.6 | M20 × 2.5 | 245 |
| M10 × 1.5 | 58.0 | M24 × 3 | 353 |
| M12 × 1.75 | 84.3 | M30 × 3.5 | 561 |
| M14 × 2 | 115 | M36 × 4 | 817 |
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Except as provided in 4.2.3, nuts are furnished in the condition below (4.2.2). When required, stress relieving is specified by the purchaser for all copper alloys and nickel alloys 400 and 405 (4.2.3). Unless otherwise specified, nuts may be hot pressed, cold formed or machined at the manufacturer's option (4.2.1).
| Alloy | Condition |
|---|---|
| Copper (all alloys) | As formed or stress relieved at manufacturer's option |
| Nickel alloys 400 and 405 | As formed or stress relieved at manufacturer's option |
| Nickel alloy 500 | Solution annealed and aged |
| Aluminum alloy 2024-T4 | Solution treated and naturally aged |
| Aluminum alloy 6061-T6 | Solution treated and artificially aged |
| Aluminum alloy 6262-T9 | Solution treated, artificially aged, and cold worked |
| Titanium 625 | Annealed |
UNS C66100 is alloy 661, listed in Table 1 of ASTM F467-13ε2 as silicon bronze. Key composition limits: silicon 2.8-3.5 %, lead 0.20-0.8 %, copper 94.0 % min. Copper alloys are furnished as formed or stress relieved at the manufacturer's option (4.2.2); when stress relieving is required, the purchaser specifies it (4.2.3). When the purchaser specifies Supplementary Requirement S1, the nuts must show no cracking after 30 min immersion in aqueous mercurous nitrate per ASTM B154.
Table 2 requires a minimum hardness of 75 HRB and a minimum proof stress of 70 ksi for hex nuts and 76 ksi for heavy hex nuts. Heavy hex values are 1.08 times the hex nut value (note B). Where both proof load and hardness are tested, proof load governs acceptance (6.2).
Proof load is the Table 2 proof stress times the Table 4 tensile stress area (13.2.1, tested per ASTM F606). For 1/2-13 UNC the stress area is 0.1419 sq in, so a hex nut must carry 9,933 lbf (70 ksi) and a heavy hex nut 10,784 lbf (76 ksi) without failure.
Each nut carries the manufacturer's symbol and the Table 2 marking F467M, raised or depressed (17.1). Unless otherwise specified, dimensions are to ASME B18.2.2 (7.1), threads are Class 2B to ASME B1.1 (7.2) and nuts are furnished without any additive chemical or metallic finish (8.2). Mating bolts, cap screws and studs are covered by ASTM F468 (1.2). Note that the alloy 661 marking F467M is the marking symbol in Table 2, not the metric specification F467M.
