S-91253A566 1/4"-20 x 4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength – With 130,000 psi tensile strength and Rockwell C39 hardness, this screw provides reliable, long-lasting fastening in demanding applications.
• Corrosion-Resistant Black-Oxide Finish – The alloy steel with black-oxide coating offers enhanced durability and protection against rust in industrial environments.
• Secure Hex Drive Engagement – The 5/32" hex drive ensures easy installation with standard tools and reduces the risk of stripping or cam-out.
• Precision UNC Coarse Threading – Class 3A thread fit and coarse thread spacing deliver superior holding power and faster assembly in various materials.
• Optimized Flat Head Design – The 82° countersink angle and standard flat head profile allow for a flush, low-profile finish that minimizes protrusion.
• Partially Threaded Shank – Provides unthreaded grip length for better clamping force and alignment in structural applications.
• Comprehensive Compliance – Meets ASTM F835 specifications and is RoHS 3 and REACH compliant, ensuring safety and environmental standards are met.

Professional Applications & Engineering Value

This 1/4"-20 x 4" black-oxide alloy steel flat head screw is engineered for heavy-duty industrial use, where high tensile strength and corrosion resistance are critical. Its UNC coarse threading and Class 3A thread fit ensure precise, secure fastening in metal, wood, and composite assemblies, reducing the risk of loosening under vibration. The hex drive design allows for efficient installation with common tools, while the 82° countersink angle and flat head provide a smooth, flush finish that enhances aesthetics and safety in machinery, automotive, and construction applications. By combining robust alloy steel with a protective black-oxide finish, this screw addresses common issues like wear and environmental exposure, offering reliable performance in harsh conditions.

Specification Summary & Compliance

This screw features a 1/4"-20 UNC coarse thread with Class 3A thread fit for high precision, a partially threaded shank with a minimum thread length of 1", and dimensions including a 0.531" head diameter and 4" length. It complies with ASTM F835 standards for mechanical properties and is RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, ensuring it meets environmental and safety regulations for industrial use.