Material specification page for thread cutting screws (type f) 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 DIN 7516.
Why Choose A4 Stainless Steel for Thread Cutting Screws (Type F)
Specified for marine, coastal and chemical applications. For thread cutting screws (type f), 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 Thread Cutting Screws (Type F) in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Thread Cutting Screws (Type F), the alternative stainless grade is A2 (304). A2 (304) suits general indoor and outdoor service; A4 (316) adds molybdenum for marine and chloride environments. Where higher strength matters more than corrosion, switch to plated alloy-steel class 8.8 or 10.9.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so in the presence of an electrolyte — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. The effect is driven by the area ratio: a small stainless fastener in a large aluminum section is normally acceptable, while a large stainless fastener in thin aluminum is not. Where the joint is wet, isolate the two metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of Thread Cutting Screws (Type F) Available in A4 Stainless Steel
| Thread size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Core hole in steel (mm) | Max material thickness (mm) | Common length range (mm) | Reference standard |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.6 | 2.4 | 2.65 | 3 | 6~25 | DIN 7516 |
| M4 | 0.7 | 8.0 | 3.1 | 3.55 | 4 | 8~30 | DIN 7516 |
| M5 | 0.8 | 9.5 | 3.7 | 4.50 | 5 | 8~40 | DIN 7516 |
| M6 | 1.0 | 12.0 | 4.6 | 5.40 | 6 | 10~50 | DIN 7516 |
| M8 | 1.25 | 16.0 | 6.0 | 7.20 | 8 | 12~50 | DIN 7516 |
| M10 | 1.5 | 20.0 | 7.5 | 9.00 | 10 | 16~60 | DIN 7516 |
