A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. Specified on r-clips (hairpin cotter pins) 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 R-Clips (Hairpin Cotter Pins)
Specified for marine, coastal and chemical applications. For r-clips (hairpin cotter pins), 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 R-Clips (Hairpin Cotter Pins) in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
For stainless r-clips (hairpin cotter pins) the compatibility question is galvanic rather than galling: joined to aluminum or galvanized steel in wet service, stainless drives corrosion of the less-noble metal. Isolate with a coating, sleeve or non-conductive washer where the joint sees moisture. Note also that stainless is softer than hardened carbon steel, so where the part carries a wear or shear duty, check the load against the grade before substituting.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so with an electrolyte present — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. Area ratio decides how bad it gets: a small stainless fastener in a large aluminum section is normally acceptable, a large stainless fastener in thin aluminum is not. Where the joint gets wet, isolate the metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of R-Clips (Hairpin Cotter Pins) Available in A4 Stainless Steel
| For pin diameter (mm) | Wire diameter (mm) | Usable length (mm) | Overall length (mm) | Fits cross hole (mm) | Material | Finish | Re-use |
|---|---|---|---|---|---|---|---|
| 5 | 1.6 | 30 | 40 | 2.0 | Spring steel | Zinc plated | Yes, if not sprung |
| 6 | 2.0 | 40 | 52 | 2.5 | Spring steel | Zinc plated | Yes, if not sprung |
| 8 | 2.5 | 50 | 65 | 3.0 | Spring steel | Zinc plated | Yes, if not sprung |
| 10 | 3.0 | 60 | 80 | 3.5 | Spring steel | Zinc plated | Yes, if not sprung |
| 13 | 4.0 | 80 | 105 | 4.5 | Spring steel | Zinc plated | Yes, if not sprung |
| 16 | 5.0 | 100 | 130 | 5.5 | Spring steel | Zinc plated | Yes, if not sprung |
Dimensions are independent of the material: every size above is available in A4 Stainless Steel.
Custom manufacturing · Made to drawing
Need this pin in a grade that is not listed?
A4 Stainless Steel is one of the grades the catalog describes. Diameter, length, tolerance class, hardness and end form are specifiable. Ground diameters are held after heat treatment rather than before. Made by cold heading or turning.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
