Material specification page for spherical washers & conical seats in A4 Stainless Steel. Covers the grade designation (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to DIN 6319.
Why Choose A4 Stainless Steel for Spherical Washers & Conical Seats
Specified for marine, coastal and chemical applications. For spherical washers & conical seats, 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 Spherical Washers & Conical Seats in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Spherical Washers & Conical Seats, 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 Spherical Washers & Conical Seats Available in A4 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 A4 Stainless Steel.
Custom manufacturing · Made to drawing
Need this washer in a grade that is not listed?
A4 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.
