Material specification page for socket set 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 ISO 4026 / ISO 4029 / DIN 913-916.
Why Choose A4 Stainless Steel for Socket Set Screws
Specified for marine, coastal and chemical applications. For socket set 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 Socket Set Screws in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Socket Set 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
Stainless steel is more noble than aluminum, so with an electrolyte present — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. Area ratio decides how bad it gets: a small stainless fastener in a large aluminum section is normally acceptable, a large stainless fastener in thin aluminum is not. Where the joint gets wet, isolate the metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of Socket Set Screws Available in A4 Stainless Steel
| Size | Pitch (mm) | Hex socket s (mm) | Engagement depth t min (mm) | Point diameter dp (mm) | End type | Reference standard |
|---|---|---|---|---|---|---|
| M1.6 | 0.35 | 0.7 | 0.7 | 0.8 | Flat point | ISO 4026 / DIN 913-916 |
| M1.6 | 0.35 | 0.7 | 0.7 | 0.8 | Cone point | ISO 4027 / DIN 913-916 |
| M1.6 | 0.35 | 0.7 | 0.7 | 0.8 | Dog point | ISO 4028 / DIN 913-916 |
| M1.6 | 0.35 | 0.7 | 0.7 | 0.8 | Cup point | ISO 4029 / DIN 913-916 |
| M2 | 0.4 | 0.9 | 0.9 | 1.0 | Flat point | ISO 4026 / DIN 913-916 |
| M2 | 0.4 | 0.9 | 0.9 | 1.0 | Cone point | ISO 4027 / DIN 913-916 |
| M2 | 0.4 | 0.9 | 0.9 | 1.0 | Dog point | ISO 4028 / DIN 913-916 |
| M2 | 0.4 | 0.9 | 0.9 | 1.0 | Cup point | ISO 4029 / DIN 913-916 |
| M2.5 | 0.45 | 1.3 | 1.1 | 1.5 | Flat point | ISO 4026 / DIN 913-916 |
| M2.5 | 0.45 | 1.3 | 1.1 | 1.5 | Cone point | ISO 4027 / DIN 913-916 |
| M2.5 | 0.45 | 1.3 | 1.1 | 1.5 | Dog point | ISO 4028 / DIN 913-916 |
| M2.5 | 0.45 | 1.3 | 1.1 | 1.5 | Cup point | ISO 4029 / DIN 913-916 |
| M3 | 0.5 | 1.5 | 1.4 | 2.0 | Flat point | ISO 4026 / DIN 913-916 |
| M3 | 0.5 | 1.5 | 1.4 | 2.0 | Cone point | ISO 4027 / DIN 913-916 |
| M3 | 0.5 | 1.5 | 1.4 | 2.0 | Dog point | ISO 4028 / DIN 913-916 |
| M3 | 0.5 | 1.5 | 1.4 | 2.0 | Cup point | ISO 4029 / DIN 913-916 |
| M4 | 0.7 | 2.0 | 2.0 | 2.5 | Flat point | ISO 4026 / DIN 913-916 |
| M4 | 0.7 | 2.0 | 2.0 | 2.5 | Cone point | ISO 4027 / DIN 913-916 |
| M4 | 0.7 | 2.0 | 2.0 | 2.5 | Dog point | ISO 4028 / DIN 913-916 |
| M4 | 0.7 | 2.0 | 2.0 | 2.5 | Cup point | ISO 4029 / DIN 913-916 |
| M5 | 0.8 | 2.5 | 2.5 | 3.5 | Flat point | ISO 4026 / DIN 913-916 |
| M5 | 0.8 | 2.5 | 2.5 | 3.5 | Cone point | ISO 4027 / DIN 913-916 |
| M5 | 0.8 | 2.5 | 2.5 | 3.5 | Dog point | ISO 4028 / DIN 913-916 |
| M5 | 0.8 | 2.5 | 2.5 | 3.5 | Cup point | ISO 4029 / DIN 913-916 |
| M6 | 1.0 | 3.0 | 3.0 | 4.0 | Flat point | ISO 4026 / DIN 913-916 |
| M6 | 1.0 | 3.0 | 3.0 | 4.0 | Cone point | ISO 4027 / DIN 913-916 |
| M6 | 1.0 | 3.0 | 3.0 | 4.0 | Dog point | ISO 4028 / DIN 913-916 |
| M6 | 1.0 | 3.0 | 3.0 | 4.0 | Cup point | ISO 4029 / DIN 913-916 |
| M8 | 1.25 | 4.0 | 4.0 | 5.5 | Flat point | ISO 4026 / DIN 913-916 |
| M8 | 1.25 | 4.0 | 4.0 | 5.5 | Cone point | ISO 4027 / DIN 913-916 |
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. Material and finish are usually what drives a special — a grade the standard part is not stocked in, or a coating chosen against a salt-spray figure instead of a default. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

