S-91253A389 1/2"-20 x 3" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Enhanced Durability & Corrosion Resistance - Black-oxide coating on alloy steel provides superior protection against rust and wear in harsh industrial environments.
• High Tensile Strength for Demanding Applications - 130,000 psi tensile strength and Rockwell C39 hardness ensure reliable performance under heavy loads and stress.
• Precision Thread Fit for Secure Fastening - Class 3A thread fit offers tighter tolerances, reducing the risk of loosening and improving assembly reliability.
• Efficient Hex Drive Installation - 5/16" hex drive allows for quick, secure tool engagement, minimizing slippage and speeding up installation.
• Optimized Countersink Design - 82° flat head profile ensures a flush finish, reducing snagging and improving aesthetic integration in assembled products.
• Fine Thread Spacing for Enhanced Grip - UNF fine threads provide better holding power in materials where vibration resistance is critical.
• Partial Threading for Versatile Use - Partially threaded design allows for precise clamping force control in varied material thicknesses.

Professional Applications & Engineering Value

Engineered for industrial applications requiring precision and longevity, these black-oxide alloy steel screws address common challenges like vibration-induced loosening and environmental corrosion. The UNF fine thread configuration enhances grip in metal assemblies, while the Class 3A thread fit ensures consistent engagement without cross-threading. The flat head with 82° countersink angle provides a seamless finish, ideal for machinery, automotive components, and structural frameworks where surface smoothness and high tensile strength are paramount. This combination of material properties and design features reduces maintenance frequency and improves operational safety in demanding settings.

Specification Summary & Compliance

This screw maintains Class 3A thread fit per UNF standards, with precise dimensions including 1/2"-20 thread size and 3" length. Manufacturing adheres to ASTM F835 specifications, ensuring consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and regulatory alignment for global industrial use.