A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) is the most common stainless group for indoor and general outdoor fasteners. When spherical washers & conical seats are specified in this grade, the dimensions remain per DIN 6319; the material determines corrosion behavior (good general corrosion resistance) 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 A2 Stainless Steel for Spherical Washers & Conical Seats
The most common stainless group for indoor and general outdoor fasteners. For spherical washers & conical seats, this matters when good general corrosion resistance is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Good general corrosion resistance |
Galvanic & Galling Considerations
For stainless spherical washers & conical seats 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 Spherical Washers & Conical Seats, the alternative stainless grade is A4 (316). 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
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 Spherical Washers & Conical Seats Available in A2 Stainless Steel
| Bolt size | Bore d1 (mm) | Outer diameter d2 (mm) | Height h Form C (mm) | Thickness s (mm) | Conical seat height Form D (mm) | Spherical radius R (mm) | Max misalignment | Reference standard |
|---|---|---|---|---|---|---|---|---|
| M5 | 5.5 | 12 | 3.5 | 3.5 | 3.0 | 9 | 3 deg | DIN 6319 C/D |
| M6 | 6.4 | 14 | 3.5 | 3.5 | 3.0 | 10.5 | 3 deg | DIN 6319 C/D |
| M8 | 8.4 | 17 | 4.5 | 4.5 | 3.5 | 12.5 | 3 deg | DIN 6319 C/D |
| M10 | 10.5 | 21 | 5.0 | 5.0 | 4.0 | 15.5 | 3 deg | DIN 6319 C/D |
| M12 | 13 | 24 | 6.0 | 6.0 | 5.0 | 17.5 | 3 deg | DIN 6319 C/D |
| M14 | 15 | 28 | 7.0 | 7.0 | 5.5 | 20.5 | 3 deg | DIN 6319 C/D |
| M16 | 17 | 30 | 7.0 | 7.0 | 6.0 | 22 | 3 deg | DIN 6319 C/D |
| M20 | 21 | 36 | 8.5 | 8.5 | 7.0 | 26.5 | 3 deg | DIN 6319 C/D |
| M24 | 25 | 44 | 10 | 10 | 8.0 | 32 | 3 deg | DIN 6319 C/D |
| M30 | 31 | 56 | 12 | 12 | 10 | 40 | 3 deg | DIN 6319 C/D |
Dimensions are independent of the material: every size above is available in A2 Stainless Steel.
Custom manufacturing · Made to drawing
Need this washer in a grade that is not listed?
A2 Stainless Steel is one of the grades the catalog describes. Bore and outside diameter are set by the joint rather than by the bolt, which is why an off-table size is so often the right answer. Made by stamping or punching.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
