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). A2 (304) suits general indoor and outdoor service; A4 (316) adds molybdenum for marine and chloride environments. Where higher strength matters more than corrosion, switch to plated alloy-steel class 8.8 or 10.9.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so in the presence of an electrolyte — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. The effect is driven by the area ratio: a small stainless fastener in a large aluminum section is normally acceptable, while a large stainless fastener in thin aluminum is not. Where the joint is wet, isolate the two 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 |
