S-91253A385 1/2"-20 x 2 1/2" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide finish, ideal for harsh industrial environments
• Exceptional tensile strength of 130,000 psi ensures reliable performance under heavy loads
• Precise Class 3A thread fit provides secure, vibration-resistant connections in critical applications
• Partially threaded design allows for controlled clamping force and reduced material stress
• 82° countersink angle enables flush mounting for streamlined surfaces and improved safety
• Hex drive compatibility with 5/16" drive for easy installation and high-torque applications
• Rockwell C39 hardness delivers excellent wear resistance and long-term durability

Professional Applications & Engineering Value

This black-oxide alloy steel flat head screw with 1/2"-20 UNF fine threading is engineered to address critical fastening challenges in industrial machinery, automotive assemblies, and structural applications. The combination of high tensile strength and Class 3A thread fit ensures vibration resistance in high-stress environments, while the partially threaded design provides optimal clamping force distribution. The 82° countersink angle creates seamless surface integration, preventing snagging and improving aerodynamic profiles. These hex drive screws are particularly valuable in applications requiring repeated disassembly and reassembly, where corrosion resistance and thread integrity are paramount for maintenance efficiency and equipment longevity.

Specification Summary & Compliance

Manufactured to ASTM F835 specifications with Class 3A thread fit for precision UNF threading. The screw features a 2 1/2" length with minimum 1 1/2" thread length and 0.5" thread diameter. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global industrial markets.