A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. Specified on miniature captive pan-head screws it determines the corrosion behaviour (superior, including marine and chloride environments) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint); the dimensions are ours rather than a standard's, and are listed in full below.
Why Choose A4 Stainless Steel for Miniature Captive Pan-Head Screws
Specified for marine, coastal and chemical applications. For miniature captive pan-head screws, this matters when superior, including marine and chloride environments is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Superior, including marine and chloride environments |
Corrosion Behavior in Service
A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For Miniature Captive Pan-Head Screws in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
Two important notes for stainless miniature captive pan-head screws: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
Using Stainless Fasteners in Aluminum
The galvanic couple here runs the wrong way: aluminum is the less noble metal, so it corrodes and the fastener does not. What governs the rate is the ratio of areas — a large anode and a small cathode is a tolerable combination, the reverse concentrates the attack into thin material around the hole. An isolating washer plus sealant breaks the circuit; where that is impractical, match the fastener to the substrate.
Sizes of Miniature Captive Pan-Head Screws Available in A4 Stainless Steel
| Thread size | Length options (mm) | Head diameter (mm) | Captive length (mm) | Under-head length (mm) | Maximum torque (N·m) |
|---|---|---|---|---|---|
| M1.4 | 4 / 5 / 6 / 8 / 10 | 2.0 | 2.0 | 0.5 | 0.03 |
| M1.6 | 4 / 5 / 6 / 8 / 10 | ||||
| M1.7 | 4 / 5 / 6 / 8 / 10 | ||||
| M2.0 | 4 / 5 / 6 / 8 / 10 | ||||
| M2.5 | 4 / 5 / 6 / 8 / 10 | ||||
| M2.6 | 4 / 5 / 6 / 8 / 10 | 4.0 | 1.8 | 0.16 |
Dimensions are independent of the material: every size above is available in A4 Stainless Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
A4 Stainless Steel is one of the grades the catalog describes. Head form and drive can be specified to the assembly rather than to a standard: a larger bearing face, a security drive, or a socket sized for the tool already on the bench. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
