A2 Stainless Steel Low Head Socket Cap Screws combine the dimensional form of DIN 7984 with the material properties of grade ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70: good general corrosion resistance, largely non-magnetic, service range approx. -200 °C to +400 °C, subject to the property class and the joint. This page summarizes the grade data, its corrosion behavior in service, the comparable grades, and the sizes supplied.
Why Choose A2 Stainless Steel for Low Head Socket Cap Screws
The most common stainless group for indoor and general outdoor fasteners. For low head socket cap screws, this matters when good general corrosion resistance is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Good general corrosion resistance |
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.
Comparable Grades
For Low Head Socket Cap Screws, the alternative stainless grade is A4 (316). 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 Low Head Socket Cap Screws Available in A2 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 A2 Stainless Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
A2 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.
