A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) is the most common stainless group for indoor and general outdoor fasteners. When weld studs (cd and drawn-arc) are specified in this grade, the dimensions remain per ISO 13918; the material determines corrosion behavior (good general corrosion resistance) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint). Both are covered below with the size table.
Why Choose A2 Stainless Steel for Weld Studs (CD and Drawn-Arc)
The most common stainless group for indoor and general outdoor fasteners. For weld studs (cd and drawn-arc), 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 weld studs (cd and drawn-arc): (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 Weld Studs (CD and Drawn-Arc), the alternative stainless grade is A4 (316). 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 Weld Studs (CD and Drawn-Arc) Available in A2 Stainless Steel
| Thread size | Length L before weld (mm) | Weld process | Burn-off (mm) | Minimum sheet thickness (mm) | Flange diameter (mm) | Material | Reference standard |
|---|---|---|---|---|---|---|---|
| M3 | 8 | CD (type PT) | 0.5 | 0.6 | u2014 | Mild steel / A2 | ISO 13918 |
| M4 | 10 | CD (type PT) | 0.5 | 0.7 | u2014 | Mild steel / A2 | ISO 13918 |
| M5 | 16 | CD (type PT) | 0.5 | 0.8 | u2014 | Mild steel / A2 | ISO 13918 |
| M6 | 20 | CD (type PT) | 0.5 | 1.0 | u2014 | Mild steel / A2 | ISO 13918 |
| M8 | 25 | Drawn-arc (type PD) | 4.0 | 2.0 | 13.0 | Mild steel | ISO 13918 |
| M10 | 30 | Drawn-arc (type PD) | 4.0 | 2.5 | 16.0 | Mild steel | ISO 13918 |
| M12 | 40 | Drawn-arc (type PD) | 5.0 | 3.0 | 19.0 | Mild steel | ISO 13918 |
