Material specification page for oval-head sheet-metal screws in A4 Stainless Steel. Covers the grade designation (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to Trade series (oval sheet-metal screws).
Why Choose A4 Stainless Steel for Oval-Head Sheet-Metal Screws
Specified for marine, coastal and chemical applications. For oval-head sheet-metal screws, 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 Oval-Head Sheet-Metal Screws in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Oval-Head Sheet-Metal Screws, 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 Oval-Head Sheet-Metal Screws Available in A4 Stainless Steel
| Size example | Head diameter (in) | Head height (in) | Drive | Thread pitch | Length options (in) | Material |
|---|---|---|---|---|---|---|
| #4 | 0.212 | 0.104 | No. 1 | 24 TPI | 3/8~1 | 18-8 stainless steel |
| #6 | 0.262 | 0.128 | No. 2 | 18 TPI | 3/8~1 | 18-8 stainless steel |
