S-91253A309 1/4"-28 x 1" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior tensile strength of 130,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Precision Class 3A thread fit provides tight, secure mating with nuts and tapped holes, minimizing backlash and improving assembly accuracy.
• Black-oxide finish on alloy steel offers enhanced corrosion resistance, extending service life in demanding industrial environments.
• Fully threaded design allows for maximum grip length and adjustability, ensuring consistent clamping force across the entire fastener.
• 82° countersink angle and flat head enables a flush, low-profile installation, ideal for applications where surface clearance is critical.
• 5/32" hex drive facilitates easy installation and removal with standard tools, speeding up assembly and maintenance processes.
• High Rockwell C39 hardness provides excellent wear resistance, maintaining thread integrity through repeated use.

Professional Applications & Engineering Value

This 1/4"-28 UNF flat head socket cap screw is engineered to address critical challenges in precision assemblies, such as machinery, automotive components, and electronic enclosures. The black-oxide alloy steel construction combats corrosion, while the fine thread and Class 3A fit ensure vibration resistance and leak-proof connections in dynamic environments. Its fully threaded body and 82° countersink allow for seamless integration into tapered holes, providing a secure, flush finish that prevents snagging and maintains aerodynamic or aesthetic surfaces. Ideal for applications requiring high tensile strength and compliance with rigorous industry standards, this screw minimizes maintenance downtime and enhances long-term reliability.

Specification Summary & Compliance

This screw adheres to ASME B18.3 and ASTM F835 specifications, ensuring dimensional accuracy and performance consistency. The UNF fine thread with Class 3A fit guarantees precise tolerances, while the black-oxide surface treatment meets environmental regulations, including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance, confirming it is free from hazardous substances and suitable for global industrial use.