Material specification page for automotive push-type retainers in A2 Stainless Steel. Covers the grade designation (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to Trade series (automotive push-type retainers).
Why Choose A2 Stainless Steel for Automotive Push-Type Retainers
The most common stainless group for indoor and general outdoor fasteners. For automotive push-type retainers, 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 |
Corrosion Behavior in Service
A2 (304) gives excellent atmospheric and most-water corrosion resistance and is the most common stainless for Automotive Push-Type Retainers in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).
Comparable Grades
For Automotive Push-Type Retainers, 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
The galvanic couple here runs the wrong way: aluminum is the less noble metal, so it corrodes and the fastener does not. What governs the rate is the ratio of areas — a large anode and a small cathode is a tolerable combination, the reverse concentrates the attack into thin material around the hole. An isolating washer plus sealant breaks the circuit; where that is impractical, match the fastener to the substrate.
Sizes of Automotive Push-Type Retainers Available in A2 Stainless Steel
| Installation | Rear access | Fit governed by | Reusable |
|---|---|---|---|
| pushed in by hand | not required | panel hole, panel thickness, head diameter | usually not |
| pushed in, screw-expanded centre | not required | panel hole, panel thickness, head diameter | yes, with care |
| pushed in, fir-tree stem | not required | panel hole and panel thickness | usually not |

