Captive Panel Screws, Spring-Loaded manufactured in A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) are dimensioned to Trade series (panel fastener). The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose A4 Stainless Steel for Captive Panel Screws, Spring-Loaded
Specified for marine, coastal and chemical applications. For captive panel screws, spring-loaded, 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 Captive Panel Screws, Spring-Loaded in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Captive Panel Screws, Spring-Loaded, the alternative stainless grade is A2 (304). The practical dividing line is chlorides: A2 (304) is fine until salt is involved, and A4 (316) exists for the cases where it is — coastal, marine and road-salt service. Neither reaches the strength of a plated class 8.8 or 10.9 fastener.
Using Stainless Fasteners in Aluminum
Expect the aluminum to corrode, not the fastener — stainless sits higher in the galvanic series, so the aluminum is the one that gives up material. A small fastener in a thick section spreads the loss over a large area and is usually fine; a large fastener in thin sheet concentrates it and is not. Keep water out of the joint, or isolate the two metals with a nylon or coated washer and a sealant.
Sizes of Captive Panel Screws, Spring-Loaded Available in A4 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 |
