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These G316 marine-grade stainless steel Phillips flat-head countersunk machine screws are built for environments where corrosion resistance is critical. G316 stainless steel contains molybdenum (2–3%), which provides substantially better resistance to chloride-induced pitting and crevice corrosion compared to standard 304 stainless — making it the correct specification for marine, coastal, and saltwater applications. The 90-degree conical countersunk head sits flush with or below the surface when installed in a properly countersunk hole, providing a clean, snag-free finish that is especially important on boats, docks, and marine structures.
Available in four metric sizes — M3, M4, M5, and M6 — with multiple lengths per size and flexible pack quantities from 5 to 100 pieces. All sizes use ISO metric coarse pitch threads and require a pre-tapped hole, threaded insert, or nut. These are not self-tapping screws.
| Material | G316 Marine Grade Stainless Steel (AISI 316 / 1.4401) |
|---|---|
| Molybdenum Content | 2–3% (superior chloride corrosion resistance vs. 304 SS) |
| Screw Type | Machine Screw — Flat Head (Countersunk) |
| Head Type | Flat Head / Countersunk (90° conical, ISO metric) |
| Drive Type | Phillips (Cross Recess) |
| Thread Standard | ISO Metric Coarse Pitch |
| Available Sizes | M3, M4, M5, M6 |
| Thread Pitches | M3: 0.5mm | M4: 0.7mm | M5: 0.8mm | M6: 1.0mm |
| Phillips Driver Sizes | M3: PH1 | M4/M5: PH2 | M6: PH3 |
| Available Lengths (M3) | 4, 6, 8, 10, 12, 16, 18, 20, 25, 30mm |
| Available Lengths (M4) | 6, 8, 10, 12, 16, 18, 20, 25, 30, 35mm |
| Available Lengths (M5) | 8, 10, 12, 16, 18, 20, 25, 30, 35, 40mm |
| Available Lengths (M6) | 10, 12, 16, 18, 20, 25, 30, 35, 40, 45mm |
| Pack Quantity Options | 5 / 10 / 20 / 30 / 40 / 50 / 60 / 100 pcs (varies by size) |
| Head Angle | 90° (ISO metric countersunk standard) |
| Self-Tapping | No — requires pre-tapped hole or nut |
| Countersinking Required | Yes — for flush installation |
| Corrosion Resistance | Excellent — suitable for marine, coastal, and saltwater environments |
| Galling Risk | Use anti-seize lubricant when threading into stainless steel |
G316 (AISI 316) is an austenitic stainless steel alloy containing 2–3% molybdenum, which significantly improves resistance to chloride corrosion, pitting, and crevice corrosion compared to standard 304 stainless steel. It is the preferred specification for marine, coastal, and saltwater environments.
G316 contains molybdenum (2–3%), providing significantly better resistance to chloride-induced pitting and crevice corrosion. In marine and coastal environments, 304 can develop rust spots and pitting relatively quickly when exposed to salt water or salt air. G316 is substantially more resistant and is the standard specification for marine-grade fasteners.
M3: PH1. M4 and M5: PH2. M6: PH3. Using the correct driver size reduces cam-out and head damage.
No. These are machine screws with ISO metric coarse thread. They require a pre-tapped hole, threaded insert, or nut.
Yes. Stainless steel fasteners are susceptible to galling when threaded into stainless steel. Use an anti-seize lubricant on the threads before installation; install at a slow, steady speed; avoid high-speed power tools for final tightening.
ISO metric coarse pitch: M3 (0.5mm) | M4 (0.7mm) | M5 (0.8mm) | M6 (1.0mm). Compatible with standard metric nuts, threaded inserts, and tapped holes.
