A4 Stainless Steel Low Head Socket Cap Screws are supplied to DIN 7984. The grade provides superior, including marine and chloride environments and is largely non-magnetic; the practical service range is approx. -200 °C to +400 °C, subject to the property class and the joint. Property data, grade comparison and the full size table follow.
Why Choose A4 Stainless Steel for Low Head Socket Cap Screws
Specified for marine, coastal and chemical applications. For low head socket cap 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 Low Head Socket Cap Screws in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
Two important notes for stainless low head socket cap screws: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
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 Low Head Socket Cap Screws Available in A4 Stainless Steel
| Size | Pitch P (mm) | b (mm) | Head diameter dk (mm) | da (mm) | ds_min (mm) | e (mm) | Head height k (mm) | r (mm) | Hex socket s (mm) | t (mm) | v (mm) | dw (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 12 | 5.5 | 3.6 | 2.86 | 2.3 | 2.0 | 0.1 | 2.0 | 1.5 | 0.3 | 4.84 | 5~20 | DIN 7984 |
| M4 | 0.7 | 14 | 7.0 | 4.7 | 3.82 | 2.87 | 2.8 | 0.2 | 2.5 | 2.3 | 0.4 | 6.2 | 6~25 | DIN 7984 |
| M5 | 0.8 | 16 | 8.5 | 5.7 | 4.82 | 3.44 | 3.5 | 0.2 | 3.0 | 2.7 | 0.5 | 7.7 | 8~30 | DIN 7984 |
| M6 | 1.0 | 18 | 10.0 | 6.8 | 5.82 | 4.58 | 4.0 | 0.25 | 4.0 | 3.0 | 0.6 | 9.2 | 10~40 | DIN 7984 |
| M8 | 1.25 | 22 | 13.0 | 9.2 | 7.7 | 5.72 | 5.0 | 0.4 | 5.0 | 3.8 | 0.8 | 12.03 | 12~60 | DIN 7984 |
| M10 | 1.5 | 26 | 16.0 | 11.2 | 9.78 | 8.01 | 6.0 | 0.4 | 7.0 | 4.5 | 1.0 | 15.03 | 16~70 | DIN 7984 |
| M12 | 1.75 | 30 | 18.0 | 13.7 | 11.73 | 9.15 | 7.0 | 0.6 | 8.0 | 5.0 | 1.2 | 17.03 | 20~80 | DIN 7984 |
| (M14) | 2.0 | 34 | 21.0 | 15.7 | 13.73 | 11.43 | 8.0 | 0.6 | 10.0 | 5.3 | 1.4 | 19.83 | 30~80 | DIN 7984 |
| M16 | 2.0 | 38 | 24.0 | 17.7 | 15.73 | 13.72 | 9.0 | 0.6 | 12.0 | 5.5 | 1.6 | 22.83 | 30~80 | DIN 7984 |
| (M18) | 2.5 | 42 | 27.0 | 20.2 | 17.73 | 13.72 | 10.0 | 0.6 | 12.0 | 6.5 | 1.8 | 25.83 | 40~100 | DIN 7984 |
| M20 | 2.5 | 46 | 30.0 | 22.4 | 19.67 | 16.0 | 11.0 | 0.8 | 14.0 | 7.5 | 2.0 | 28.83 | 40~100 | DIN 7984 |
| (M22) | 2.5 | 50 | 33.0 | 24.4 | 21.67 | 16.0 | 12.0 | 0.8 | 14.0 | 8.0 | 2.2 | 31.61 | 50~100 | DIN 7984 |
| M24 | 3.0 | 54 | 36.0 | 26.4 | 23.67 | 19.44 | 13.0 | 0.8 | 17.0 | 8.0 | 2.4 | 34.61 | 50~100 | DIN 7984 |
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. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
