For bearing lock washers (mb series) in A2 Stainless Steel, the controlling selection factors are corrosion exposure, strength requirement and service temperature. The grade data for A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) is summarized below together with every size supplied.
Why Choose A2 Stainless Steel for Bearing Lock Washers (MB Series)
The most common stainless group for indoor and general outdoor fasteners. For bearing lock washers (mb series), 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 |
Corrosion Behavior in Service
A2 (304) gives excellent atmospheric and most-water corrosion resistance and is the most common stainless for Bearing Lock Washers (MB Series) in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).
Galvanic & Galling Considerations
For stainless bearing lock washers (mb 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 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 Bearing Lock Washers (MB Series) Available in A2 Stainless Steel
| Designation | Shaft thread | Bore d1 (mm) | Outer diameter d2 (mm) | Thickness s (mm) | Number of outer tabs | Mating lock nut | Reference standard |
|---|---|---|---|---|---|---|---|
| MB0 | M10x0.75 | 10 | 21 | 1.0 | 11 | KM0 | DIN 5406 |
| MB1 | M12x1 | 12 | 25 | 1.0 | 11 | KM1 | DIN 5406 |
| MB2 | M15x1 | 15 | 28 | 1.0 | 11 | KM2 | DIN 5406 |
| MB3 | M17x1 | 17 | 32 | 1.0 | 11 | KM3 | DIN 5406 |
| MB4 | M20x1 | 20 | 36 | 1.0 | 11 | KM4 | DIN 5406 |
| MB5 | M25x1.5 | 25 | 42 | 1.25 | 13 | KM5 | DIN 5406 |
| MB6 | M30x1.5 | 30 | 49 | 1.25 | 13 | KM6 | DIN 5406 |
| MB7 | M35x1.5 | 35 | 57 | 1.25 | 13 | KM7 | DIN 5406 |
| MB8 | M40x1.5 | 40 | 62 | 1.25 | 13 | KM8 | DIN 5406 |
| MB9 | M45x1.5 | 45 | 69 | 1.25 | 13 | KM9 | DIN 5406 |
| MB10 | M50x1.5 | 50 | 74 | 1.25 | 13 | KM10 | DIN 5406 |
| MB11 | M55x2 | 55 | 81 | 1.5 | 13 | KM11 | DIN 5406 |
| MB12 | M60x2 | 60 | 86 | 1.5 | 13 | KM12 | DIN 5406 |
