Low-Profile Captive Pins manufactured in A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) are dimensioned to Trade series (captive tack pins). The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose A2 Stainless Steel for Low-Profile Captive Pins
The most common stainless group for indoor and general outdoor fasteners. For low-profile captive pins, 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 Low-Profile Captive Pins 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 Low-Profile Captive Pins, 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
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 Low-Profile Captive Pins Available in A2 Stainless Steel
| Part form | Pin diameter (in) | Pin length (in) | Head diameter (in) | Head height (in) | Panel thickness (in) | Installation hole (in) | Material |
|---|---|---|---|---|---|---|---|
| T4-10-025 | 0.051 | 0.040 | 0.079 | 0.008 | 0.008~0.011; minimum 0.035 | 0.051 | 400-series stainless steel |
| TA-10-025 | 0.051 | 0.040 | 0.079 | 0.008 | 0.008~0.011; minimum 0.035 | 0.051 | aluminum |
