S-91255A509 1/4"-28 x 3" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional durability with 120,000 psi tensile strength and Rockwell C39 hardness, ideal for high-stress industrial environments
• Superior corrosion resistance from the black-oxide coating on alloy steel, extending service life in demanding applications
• Precise thread engagement with Class 3A fit and UNF fine threads, ensuring reliable fastening and vibration resistance
• Easy installation and removal using the 5/32" hex drive, providing secure tool engagement for efficient assembly
• Full threading along the 3" length offers maximum grip and adjustability in various material thicknesses
• Compliance with major standards including ASME B18.3 and ASTM F835, guaranteeing consistent quality and performance
• Environmentally responsible manufacturing with RoHS 3 and REACH compliance, meeting global regulatory requirements

Professional Applications & Engineering Value

Engineered for demanding industrial applications, this 1/4"-28 UNF screw addresses critical engineering challenges such as joint integrity under dynamic loads and environmental exposure. The black-oxide alloy steel construction provides excellent resistance to oxidation and wear, while the fine thread spacing and Class 3A thread fit deliver superior clamping force and minimize loosening in vibrating machinery. Its rounded button head design reduces stress concentration and offers a low-profile finish, making it suitable for assemblies where clearance and aesthetics are important. Commonly used in heavy equipment, automotive systems, and precision machinery, this fully threaded screw ensures long-term reliability and maintenance efficiency.

Specification Summary & Compliance

This screw adheres to Class 3A thread tolerance for precise fit, manufactured according to UNF (Unified National Fine) thread standards. It meets ASME B18.3 and ASTM F835 specifications, ensuring dimensional accuracy and mechanical performance. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of restricted hazardous substances for safe use in various industries.