Glossary

A quarter-turn fastener is a quick-release fastener that secures panels or components with a simple 90° turn. Instead of relying on threads, it uses a cam or stud mechanism that locks into a mating receptacle when turned, providing secure clamping with minimal effort. The design often keeps the stud attached to the panel, preventing it from being misplaced during removal.

These fasteners are widely used in aerospace, automotive, marine, and industrial equipment where frequent access is required, such as for inspection or maintenance. They save time compared to traditional bolts or screws while still offering a strong, vibration-resistant hold.

A Quenched & Tempered (Q&T) bolt is a steel fastener whose high strength and toughness come from a two-stage heat treatment. The bolt (or its steel) is first austenitized and quenched (rapidly cooled) to form very hard martensite, then tempered (reheated below the critical temperature) to dial back brittleness and set a balanced combination of high tensile/yield strength, toughness, and fatigue resistance. Unlike case-hardened parts, Q&T bolts are through-hardened—the strength runs through the section, not just at the surface.

Where you’ll see them: structural steel connections, heavy equipment, automotive suspensions/driveline, wind towers, flanges/valves (e.g., A193 B7), and other high-load joints. Common families produced by Q&T include ASTM/ISO property classes like 8.8 / 10.9 / 12.9, SAE Grade 8, and structural grades such as A325/A490 (now F3125).

Notes: observe the specified coatings and installation procedures—very high-strength Q&T bolts can be susceptible to hydrogen embrittlement with some electro-zinc processes, so coatings are often restricted by the standard.