A2 Stainless Steel Vented Vacuum Screws are supplied to ISO 4762. The grade provides good general corrosion resistance and is largely non-magnetic; the practical service range is approx. -200 °C to +400 °C, subject to the property class and the joint. Property data, grade comparison and the full size table follow.
Why Choose A2 Stainless Steel for Vented Vacuum Screws
The most common stainless group for indoor and general outdoor fasteners. For vented vacuum screws, 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 Vented Vacuum Screws 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
Two important notes for stainless vented vacuum screws: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
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 Vented Vacuum Screws Available in A2 Stainless Steel
| Thread size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Hex socket s (mm) | Vent hole diameter (mm) | Common length range (mm) | Reference standard |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 3.0 | 2.5 | 0.8 | 6~30 | ISO 4762 vented |
| M4 | 0.7 | 7.0 | 4.0 | 3 | 1.0 | 8~40 | ISO 4762 vented |
| M5 | 0.8 | 8.5 | 5.0 | 4 | 1.2 | 10~50 | ISO 4762 vented |
| M6 | 1.0 | 10.0 | 6.0 | 5 | 1.5 | 10~60 | ISO 4762 vented |
| M8 | 1.25 | 13.0 | 8.0 | 6 | 2.0 | 12~80 | ISO 4762 vented |
| M10 | 1.5 | 16.0 | 10.0 | 8 | 2.5 | 16~80 | ISO 4762 vented |
