Material specification page for cross flat-head knurled self-tapping 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 GB/T 845 / DIN 7981 / GB/T 5267.1.
Why Choose A4 Stainless Steel for Cross Flat-Head Knurled Self-Tapping Screws
Specified for marine, coastal and chemical applications. For cross flat-head knurled self-tapping 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 Cross Flat-Head Knurled Self-Tapping Screws in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Cross Flat-Head Knurled Self-Tapping Screws, the alternative stainless grade is A2 (304). Choose A2 (304) for general use and A4 (316) wherever chlorides are present; the molybdenum in A4 is the whole difference. Remember that stainless is the corrosion answer, not the strength answer — for load, look at class 8.8 or 10.9 instead.
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 Cross Flat-Head Knurled Self-Tapping Screws Available in A4 Stainless Steel
| Head form | Under-head feature | Material | Finish options | Substrate |
|---|---|---|---|---|
| cross-recess flat head | under-head knurling | carbon steel | zinc plating | wood |
| cross-recess flat head | under-head knurling | carbon steel | colour zinc plating | plastic |
| cross-recess flat head | under-head knurling | carbon steel | black oxide | thin plate |
