A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. Specified on belleville washers (inch series) it determines the corrosion behaviour (superior, including marine and chloride environments) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint); the dimensions are ours rather than a standard's, and are listed in full below.
Why Choose A4 Stainless Steel for Belleville Washers (Inch Series)
Specified for marine, coastal and chemical applications. For belleville washers (inch 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 Belleville Washers (Inch Series) in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
For stainless belleville washers (inch 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 Belleville Washers (Inch Series) Available in A4 Stainless Steel
| For bolt size | Inner diameter (in) | Outer diameter (in) | Thickness (in) | Free height (in) | Load at flat (lbf) | Material | Finish |
|---|---|---|---|---|---|---|---|
| 1/4" | 0.260 | 0.550 | 0.020 | 0.034 | 270 | Carbon spring steel | Zinc |
| 5/16" | 0.322 | 0.688 | 0.025 | 0.042 | 420 | Carbon spring steel | Zinc |
| 3/8" | 0.385 | 0.812 | 0.030 | 0.050 | 620 | Carbon spring steel | Zinc |
| 1/2" | 0.510 | 1.062 | 0.040 | 0.066 | 1100 | Carbon spring steel | Zinc |
| 5/8" | 0.635 | 1.312 | 0.050 | 0.082 | 1700 | Carbon spring steel | Zinc |
| 3/4" | 0.760 | 1.562 | 0.060 | 0.098 | 2450 | Carbon spring steel | Zinc |
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.
