A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) is the most common stainless group for indoor and general outdoor fasteners. Specified on captive panel screws, spring-loaded it determines the corrosion behaviour (good general corrosion resistance) 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 A2 Stainless Steel for Captive Panel Screws, Spring-Loaded
The most common stainless group for indoor and general outdoor fasteners. For captive panel screws, spring-loaded, 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 Captive Panel Screws, Spring-Loaded 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 captive panel screws, spring-loaded: (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
The galvanic couple here runs the wrong way: aluminum is the less noble metal, so it corrodes and the fastener does not. What governs the rate is the ratio of areas — a large anode and a small cathode is a tolerable combination, the reverse concentrates the attack into thin material around the hole. An isolating washer plus sealant breaks the circuit; where that is impractical, match the fastener to the substrate.
Sizes of Captive Panel Screws, Spring-Loaded Available in A2 Stainless Steel
| Thread size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Panel hole (mm) | Panel thickness (mm) | Retracted travel (mm) | Drive |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 8.0 | 3.0 | 4.2 | 0.8~1.5 | 4.0 | Slotted / PH1 |
| M3 | 0.5 | 8.0 | 3.0 | 4.2 | 1.5~2.5 | 6.0 | Slotted / PH1 |
| M4 | 0.7 | 10.0 | 3.5 | 5.3 | 0.8~1.5 | 5.0 | Slotted / PH2 |
| M4 | 0.7 | 10.0 | 3.5 | 5.3 | 1.5~3.0 | 8.0 | Slotted / PH2 |
| M5 | 0.8 | 12.0 | 4.0 | 6.4 | 1.5~3.0 | 8.0 | PH2 / TX20 |
| M6 | 1.0 | 14.0 | 4.5 | 7.4 | 2.0~4.0 | 10.0 | PH3 / TX25 |
Dimensions are independent of the material: every size above is available in A2 Stainless Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
A2 Stainless Steel is one of the grades the catalog describes. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
