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These A4 stainless steel Phillips pan flanged head machine screws are engineered for applications where corrosion resistance and load distribution matter. A4 (ISO designation for AISI 316) stainless steel contains 2–3% molybdenum, providing substantially better resistance to chloride-induced pitting and crevice corrosion compared to standard A2 (304) stainless — making it the correct specification for marine, coastal, chemical, and food-grade environments.
The pan flanged head design combines a low-profile rounded head with an integrated flange that distributes clamping load over a larger surface area. This reduces pull-through risk in softer materials and eliminates the need for a separate washer in many applications. Available in three metric sizes — M3, M4, and M5 — with multiple lengths per size and flexible pack quantities from 5 to 200 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 | A4 Stainless Steel (AISI 316 / 1.4401) |
|---|---|
| ISO Designation | A4 (equivalent to AISI 316, G316) |
| Molybdenum Content | 2–3% (superior chloride corrosion resistance vs. A2/304) |
| Screw Type | Machine Screw |
| Head Type | Pan Flanged Head (integrated flange/washer head) |
| Drive Type | Phillips (Cross Recess) |
| Thread Standard | ISO Metric Coarse Pitch |
| Available Sizes | M3, M4, M5 |
| Thread Pitches | M3: 0.5mm | M4: 0.7mm | M5: 0.8mm |
| Phillips Driver Sizes | M3: PH1 | M4/M5: PH2 |
| Available Lengths (M3) | 4, 5, 6, 8, 10, 12, 16, 20, 25mm |
| Available Lengths (M4) | 6, 8, 10, 12, 16, 20, 25, 30mm |
| Available Lengths (M5) | 8, 10, 12, 16, 20, 25, 30mm |
| Pack Quantity Options | 5 / 10 / 20 / 30 / 50 / 100 / 200 pcs (varies by size) |
| Self-Tapping | No — requires pre-tapped hole or nut |
| Corrosion Resistance | Excellent — suitable for marine, coastal, and chemical environments |
| Galling Risk | Use anti-seize lubricant when threading into stainless steel |
A4 is the ISO designation for AISI 316 austenitic stainless steel. It contains 2–3% molybdenum, providing significantly better resistance to chloride corrosion, pitting, and crevice corrosion compared to A2 (304) stainless. It is the preferred specification for marine, coastal, and chemical environments.
A2 (304) is suitable for general indoor and mild outdoor use. A4 (316) contains molybdenum (2–3%), providing significantly better resistance to chloride-induced pitting and crevice corrosion. A4 is the correct choice for marine, coastal, saltwater, and chemical environments where A2 would corrode prematurely.
A pan flanged head combines a low-profile rounded pan head with an integrated flange (wide washer-like rim) at the base. The flange distributes clamping load over a larger surface area, reducing pull-through risk in softer materials and eliminating the need for a separate washer in many applications.
M3: PH1. M4 and M5: PH2. 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. Apply 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). Compatible with standard metric nuts, threaded inserts, and tapped holes.
