A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. Specified on server rack screws and cage-nut hardware 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 Server Rack Screws and Cage-Nut Hardware
Specified for marine, coastal and chemical applications. For server rack screws and cage-nut hardware, 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 Server Rack Screws and Cage-Nut Hardware in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
Two important notes for stainless server rack screws and cage-nut hardware: (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 Server Rack Screws and Cage-Nut Hardware Available in A4 Stainless Steel
| Thread family | Representative screw lengths | Nominal diameter / pitch | Head form | Mating hardware |
|---|---|---|---|---|
| 10-32 | 3/8 / 1/2 / 5/8 in | about 3/16 in; 32 TPI | pan head | cage nut or threaded rack hole |
| 12-24 | 3/8 / 1/2 / 5/8 in | about 7/32 in; 24 TPI | pan head | cage nut or threaded rack hole |
| M6 | 10 / 16 mm | 6 mm; 1.0 pitch | pan head | cage nut or threaded rack hole |
Dimensions are independent of the material: every size above is available in A4 Stainless Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
A4 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.
