A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. When round head grooved pins are specified in this grade, the dimensions remain per ISO 8746; the material determines corrosion behavior (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). Both are covered below with the size table.
Why Choose A4 Stainless Steel for Round Head Grooved Pins
Specified for marine, coastal and chemical applications. For round head grooved 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 |
Galvanic & Galling Considerations
For stainless round head grooved 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.
Comparable Grades
For Round Head Grooved Pins, the alternative stainless grade is A2 (304). The practical dividing line is chlorides: A2 (304) is fine until salt is involved, and A4 (316) exists for the cases where it is — coastal, marine and road-salt service. Neither reaches the strength of a plated class 8.8 or 10.9 fastener.
Using Stainless Fasteners in Aluminum
Expect the aluminum to corrode, not the fastener — stainless sits higher in the galvanic series, so the aluminum is the one that gives up material. A small fastener in a thick section spreads the loss over a large area and is usually fine; a large fastener in thin sheet concentrates it and is not. Keep water out of the joint, or isolate the two metals with a nylon or coated washer and a sealant.
Sizes of Round Head Grooved Pins Available in A4 Stainless Steel
| Nominal diameter d (mm) | d_1_max (mm) | d_1_min (mm) | d_k_max (mm) | d_k_min (mm) | k_max (mm) | k_min (mm) | r (mm) | c (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|
| 1.4 mm | 1.4 | 1.35 | 2.6 | 2.2 | 0.9 | 0.7 | 1.4 | 0.42 | 3~6 | ISO 8746 |
| 1.6 mm | 1.6 | 1.55 | 3 | 2.6 | 1.1 | 0.9 | 1.6 | 0.48 | 3~8 | ISO 8746 |
| 2 mm | 2 | 1.95 | 3.7 | 3.3 | 1.3 | 1.1 | 1.9 | 0.6 | 3~10 | ISO 8746 |
| 2.5 mm | 2.5 | 2.425 | 4.6 | 4.2 | 1.6 | 1.4 | 2.4 | 0.75 | 3~12 | ISO 8746 |
| 3 mm | 3 | 2.925 | 5.45 | 4.95 | 1.95 | 1.65 | 2.8 | 0.9 | 4~16 | ISO 8746 |
| 4 mm | 4 | 3.9 | 7.75 | 6.75 | 2.55 | 2.25 | 3.8 | 1.2 | 5~20 | ISO 8746 |
| 5 mm | 5 | 4.9 | 9.1 | 8.5 | 3.15 | 2.85 | 4.6 | 1.5 | 6~25 | ISO 8746 |
| 6 mm | 6 | 5.9 | 10.8 | 10.2 | 3.75 | 3.45 | 5.7 | 1.8 | 8~30 | ISO 8746 |
| 8 mm | 8 | 7.85 | 14.4 | 13.6 | 5 | 4.6 | 7.5 | 2.4 | 10~40 | ISO 8746 |
| 10 mm | 10 | 9.85 | 16 | 14.9 | 7.4 | 6.5 | 8 | 3 | 12~40 | ISO 8746 |
| 12 mm | 12 | 11.8 | 19 | 17.7 | 8.4 | 7.5 | 9.5 | 3.6 | 16~40 | ISO 8746 |
| 16 mm | 16 | 15.8 | 25 | 23.7 | 10.9 | 10 | 13 | 4.8 | 20~40 | ISO 8746 |
| 20 mm | 20 | 19.8 | 32 | 30.7 | 13.9 | 13 | 16.5 | 6 | 25~40 | ISO 8746 |
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.
