For flat washers, extra large series in A4 Stainless Steel, the controlling selection factors are corrosion exposure, strength requirement and service temperature. The grade data for A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is summarized below together with every size supplied.
Why Choose A4 Stainless Steel for Flat Washers, Extra Large Series
Specified for marine, coastal and chemical applications. For flat washers, extra large series, 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 Flat Washers, Extra Large Series in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
For stainless flat washers, extra large series 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 Flat Washers, Extra Large Series Available in A4 Stainless Steel
| Size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness h (mm) | h_max (mm) | Reference standard |
|---|---|---|---|---|---|
| M5 | 5.5 | 18.0 | 2.0 | 2.3 | ISO 7094 |
| M6 | 6.6 | 22.0 | 2.0 | 2.3 | ISO 7094 |
| M8 | 9.0 | 28.0 | 3.0 | 3.6 | ISO 7094 |
| M10 | 11.0 | 34.0 | 3.0 | 3.6 | ISO 7094 |
| M12 | 13.5 | 44.0 | 4.0 | 4.6 | ISO 7094 |
| (M14) | 15.5 | 50.0 | 4.0 | 4.6 | ISO 7094 |
| M16 | 17.5 | 56.0 | 5.0 | 6.0 | ISO 7094 |
| (M18) | 20.0 | 60.0 | 5.0 | 6.0 | ISO 7094 |
| M20 | 22.0 | 72.0 | 6.0 | 7.0 | ISO 7094 |
| (M22) | 24.0 | 80.0 | 6.0 | 7.0 | ISO 7094 |
| M24 | 26.0 | 85.0 | 6.0 | 7.0 | ISO 7094 |
| (M27) | 30.0 | 98.0 | 6.0 | 7.0 | ISO 7094 |
| M30 | 33.0 | 105.0 | 6.0 | 7.0 | ISO 7094 |
| (M33) | 36.0 | 115.0 | 8.0 | 9.2 | ISO 7094 |
| M36 | 39.0 | 125.0 | 8.0 | 9.2 | ISO 7094 |
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. Bearing area is usually the reason for a special washer: a larger outside diameter to spread load into a softer material, or a thicker section to resist dishing. Made by stamping or punching.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
