Material specification page for high-strength socket head cap screws (inch) 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 ASTM A574.
Why Choose A4 Stainless Steel for High-Strength Socket Head Cap Screws (Inch)
Specified for marine, coastal and chemical applications. For high-strength socket head cap screws (inch), 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 High-Strength Socket Head Cap Screws (Inch) in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For High-Strength Socket Head Cap Screws (Inch), the alternative stainless grade is A2 (304). A2 (304) covers general indoor and outdoor service. A4 (316) adds molybdenum, which is what buys the chloride resistance for marine and de-icing-salt exposure. Where strength matters more than corrosion, plated alloy steel in class 8.8 or 10.9 is the swap to make.
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 High-Strength Socket Head Cap Screws (Inch) Available in A4 Stainless Steel
| Size | Threads per inch | Head diameter (in) | Head height (in) | Hex socket (in) | Minimum tensile (ksi) | Hardness (HRC) | Reference standard |
|---|---|---|---|---|---|---|---|
| #10 | 24 | 0.312 | 0.190 | 5/32 | 180 | 39-45 | ASTM A574 |
| 1/4" | 20 | 0.375 | 0.250 | 3/16 | 180 | 39-45 | ASTM A574 |
| 5/16" | 18 | 0.469 | 0.312 | 1/4 | 180 | 39-45 | ASTM A574 |
| 3/8" | 16 | 0.562 | 0.375 | 5/16 | 180 | 39-45 | ASTM A574 |
| 1/2" | 13 | 0.750 | 0.500 | 3/8 | 180 | 39-45 | ASTM A574 |
| 5/8" | 11 | 0.938 | 0.625 | 1/2 | 180 | 39-45 | ASTM A574 |
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. Head form and drive can be specified to the assembly rather than to a standard: a larger bearing face, a security drive, or a socket sized for the tool already on the bench. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
