The chain is fine...but I ordered the wrong size. Nine links of the chain I ordered equals six of the size I wanted. My error...
How can I straighten out the springs? I can't use them coil uo as is.
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Fasten with confidence in any environment using these premium 316 stainless steel socket head cap screws. Manufactured to the GB/T Chinese national standard, these hex drive bolts deliver the strength you need (4.8 grade) and the corrosion resistance that only 316 marine-grade stainless can offer. Available in a wide range of metric diameters from M2 up to M20, and in extended lengths for through‑hole and clamping applications, they are the go‑to choice for boat rigging, outdoor structures, food processing equipment, chemical plants, and architectural projects. Each screw arrives with a light anti‑rust oil coating to preserve its pristine condition until installation. With the internal hex drive, you get a clean, flush fit and excellent torque transfer without stripping.
| Bolt Type | Socket Head Cap Screw (Internal Hex Drive) |
| Material | 316 Stainless Steel (A4) |
| Strength Grade | 4.8 (Metric property class) |
| Standard | GB/T (Chinese National Standard) |
| Surface Treatment | Natural (uncoated), with light anti-rust oil |
| Available Diameters | M2 · M2.5 · M3 · M4 · M5 · M6 · M8 · M10 · M12 · M14 · M16 · M20 |
| Pitch | Standard coarse pitch per GB/T (see detail table for the exact pitch) |
| Head Style | Cylindrical head with internal hex socket |
| Packaging | Plastic bag / Paper box |
| Diameter (d) | Pitch (P) | Head Diameter (dk max) | Head Height (k max) | Hex Socket Size (s max) |
| M3 | 0.5 | 5.68 | 3.0 | 2.58 |
| M4 | 0.7 | 7.22 | 4.0 | 3.08 |
| M5 | 0.8 | 8.72 | 5.0 | 4.095 |
| M6 | 1.0 | 10.22 | 6.0 | 5.14 |
| M8 | 1.25 | 13.27 | 8.0 | 6.14 |
| M10 | 1.5 | 16.27 | 10.0 | 8.175 |
| M12 | 1.75 | 18.27 | 12.0 | 10.18 |
| M16 | 2.0 | 24.33 | 16.0 | 14.21 |
| M20 | 2.5 | 30.33 | 20.0 | 17.23 |
* Lengths available from short to extra-long. Please select the desired specification from the variant menu. A full, detailed data sheet is available upon request.
A: 316 is an austenitic stainless steel and is generally non-magnetic. However, cold working during manufacturing (thread rolling, heading) can transform a small amount of austenite into martensite, which is magnetic. This results in very weak magnetic attraction—completely normal and does not compromise corrosion resistance.
A: You can use a 316-specific detection solution (molybdenum test), which will not discolor genuine 316. Chemical composition analysis (spectral analysis) and salt spray testing are also reliable methods. Our screws pass standardized 316 material certifications.
A: The 4.8 grade indicates a tensile strength of 400 MPa and a yield strength of 320 MPa. It is a general-purpose metric grade suitable for most non-structural and light structural applications. For heavy structural connections, higher grades like 8.8 or 10.9 are typically used, but they will not offer the same corrosion resistance as 316 stainless.
A: The oil is a temporary protective coating to prevent oxidation during storage and shipping. It does not harm the screw. You can either leave it on (it provides some lubrication during tightening) or wipe it off with a degreaser for a completely dry surface. For food-contact or cleanroom use, thorough cleaning is recommended.
A: Absolutely. 316 stainless steel is specifically designed for marine and chemical environments. It resists pitting corrosion from chlorides far better than 304. For continuous underwater use or very aggressive chemical exposure, regular rinsing with fresh water will maximize service life.