S-91253A117 4-40 x 1 1/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 130,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance provided by the black-oxide finish on alloy steel, extending service life in harsh industrial environments.
• Precise Class 3A thread fit guarantees tight, secure fastening with minimal play, ideal for applications requiring high vibration resistance.
• Hex drive design allows for high-torque installation with standard tools, speeding up assembly and reducing labor costs.
• Fully threaded shank ensures maximum grip length and uniform load distribution, enhancing joint integrity across the entire fastener.
• 82° countersink angle enables a flush fit in standard countersunk holes, providing a smooth, professional finish without protrusion.
• Compliance with ASTM F835, RoHS 3, and REACH ensures material safety and environmental responsibility, meeting global regulatory standards for industrial use.

Professional Applications & Engineering Value

These 4-40 UNC flat head screws are engineered to address critical challenges in industrial assembly, where vibration, corrosion, and high tensile loads are common. The black-oxide alloy steel construction provides excellent durability against wear and environmental exposure, while the Class 3A thread fit and coarse thread spacing ensure rapid installation and reliable retention in materials like metal and hardened plastics. The hex drive design facilitates easy access in confined spaces, reducing assembly time and tool slippage. Ideal for machinery, automotive components, and electronic enclosures, these screws deliver consistent performance in right-hand thread applications, minimizing maintenance needs and downtime.

Specification Summary & Compliance

This fastener adheres to precise dimensional standards, including Class 3A thread fit for tight tolerances and UNC coarse threading for efficient engagement. It meets ASTM F835 specifications for mechanical properties and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring no restricted substances are present. The Rockwell C39 hardness and 130,000 psi tensile strength validate its suitability for high-performance industrial use, backed by rigorous quality assurance.