A4 Stainless Steel External Tooth Lock Washers combine the dimensional form of DIN 6798 A with the material properties of grade ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80: superior, including marine and chloride environments, largely non-magnetic, service range approx. -200 °C to +400 °C, subject to the property class and the joint. This page summarizes the grade data, its corrosion behavior in service, the comparable grades, and the sizes supplied.
Why Choose A4 Stainless Steel for External Tooth Lock Washers
Specified for marine, coastal and chemical applications. For external tooth lock washers, 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 external tooth lock washers 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 External Tooth Lock Washers, the alternative stainless grade is A2 (304). Choose A2 (304) for general use and A4 (316) wherever chlorides are present; the molybdenum in A4 is the whole difference. Remember that stainless is the corrosion answer, not the strength answer — for load, look at class 8.8 or 10.9 instead.
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 External Tooth Lock Washers Available in A4 Stainless Steel
| Size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness s (mm) | Type | Reference standard |
|---|---|---|---|---|---|
| M2 | 2.2 | 4.5 | 0.3 | External teeth | DIN 6798 A |
| M2.5 | 2.7 | 5.5 | 0.4 | External teeth | DIN 6798 A |
| M3 | 3.2 | 6 | 0.4 | External teeth | DIN 6798 A |
| M3.5 | 3.7 | 7 | 0.5 | External teeth | DIN 6798 A |
| M4 | 4.3 | 8 | 0.5 | External teeth | DIN 6798 A |
| M5 | 5.3 | 10 | 0.6 | External teeth | DIN 6798 A |
| M6 | 6.4 | 11 | 0.7 | External teeth | DIN 6798 A |
| M7 | 7.4 | 12.5 | 0.8 | External teeth | DIN 6798 A |
| M8 | 8.4 | 15 | 0.8 | External teeth | DIN 6798 A |
| M10 | 10.5 | 18 | 0.9 | External teeth | DIN 6798 A |
| M12 | 13 | 20.5 | 1 | External teeth | DIN 6798 A |
| M14 | 15 | 24 | 1 | External teeth | DIN 6798 A |
| M16 | 17 | 26 | 1.2 | External teeth | DIN 6798 A |
| M18 | 19 | 30 | 1.4 | External teeth | DIN 6798 A |
| M20 | 21 | 33 | 1.4 | External teeth | DIN 6798 A |
| M22 | 23 | 36 | 1.5 | External teeth | DIN 6798 A |
| M24 | 25 | 38 | 1.5 | External teeth | DIN 6798 A |
| M27 | 28 | 44 | 1.6 | External teeth | DIN 6798 A |
| M30 | 31 | 48 | 1.6 | External teeth | DIN 6798 A |
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.
