Stainless Metric Button Head Socket Cap Screws

Metric Stainless Steel Button Head Socket Cap Screws — A2-70, ISO 7380

Shop Metric Stainless Button Head Socket Cap Screws

Metric stainless button head socket cap screws conform to ISO 7380 in A2-70 property class — A2 designates the stainless alloy (equivalent to 304/18-8, with 18% chromium and 8% nickel), and 70 indicates a minimum tensile strength of 700 MPa (~101,500 PSI). They are the correct choice when metric thread standards are required, corrosion resistance is needed, and the low-profile dome head is preferred over a standard socket head. As with all ISO 7380 button heads, maximum torque is limited by socket depth — verify load requirements before use.

A2-70 Stainless for Corrosive Environments

A2-70 stainless (304/18-8) provides excellent resistance to oxidation, moisture, and mild chemicals. Common applications for metric stainless button heads include: food processing and commercial kitchen equipment built to metric specifications; pharmaceutical and laboratory machinery; outdoor hardware and architectural components; marine hardware where 316/A4 stainless is not required; and consumer electronics, fitness equipment, and retail fixtures where appearance and corrosion resistance are both priorities.

Strength Considerations

A2-70 stainless has a minimum tensile strength of 700 MPa (~101,500 PSI) — lower than Class 10.9 alloy (1,040 MPa) and significantly lower than Class 12.9 (1,220 MPa). Combined with the inherent torque limitation of the ISO 7380 button head socket form, metric stainless button heads should be used in light to moderate load applications only. For metric applications requiring maximum clamping strength, metric alloy button head socket cap screws (Class 10.9) provide higher tensile strength, and metric socket head cap screws (ISO 4762) provide both higher strength and greater socket engagement.

Frequently Asked Questions

What does A2-70 mean for metric stainless button head socket cap screws?
A2 designates the stainless steel alloy — equivalent to 304 or 18-8 stainless (18% chromium, 8% nickel). The 70 indicates a minimum tensile strength of 700 MPa (~101,500 PSI). A2-70 is the standard property class for stainless metric fasteners in general corrosion-resistant, light-to-moderate-load applications.

Are metric stainless button heads suitable for marine use?
A2-70 (18-8/304) provides good general corrosion resistance but is not ideal for direct marine or salt-water exposure. For marine applications, A4 stainless (316 SS, which adds molybdenum for chloride resistance) is the better choice. Contact us for availability of A4 stainless metric button head socket cap screws if your application requires it.

What is the tensile strength of metric stainless button head socket cap screws?
A2-70 metric stainless button heads have a minimum tensile strength of 700 MPa (~101,500 PSI). This is lower than Class 10.9 alloy (1,040 MPa) and lower than Class 12.9 alloy (1,220 MPa). For maximum strength in a metric button head, Class 10.9 alloy is significantly stronger.

Do metric stainless button heads use the same hex key as metric alloy button heads?
Yes. A2-70 stainless and Class 10.9 alloy metric button heads of the same thread size use the same hex key. Common pairings: M5 uses 3mm, M6 uses 4mm, M8 uses 5mm, M10 uses 6mm. These differ from metric SHCS at most sizes — always confirm hex key size for the specific fastener.

Metric stainless button head socket cap screws are typically paired with other A2 stainless metric fasteners to maintain consistent material throughout the assembly — mixing stainless and carbon steel in wet environments can accelerate galvanic corrosion. For metric button head applications requiring higher strength, metric alloy button head socket cap screws (ISO 7380, Class 10.9) are significantly stronger. For metric countersunk applications, see metric stainless flat head socket cap screws (DIN 7991). The full button head selection and all socket fastener types are available through the Button Head Socket Cap Screw and Sockets categories.