S-91247A439 5/8"-18 x 2 3/4" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 120,000 psi ensures reliable performance in demanding applications
• Superior corrosion resistance with zinc plating that protects against rust and extends service life
• Precise Class 2A thread fit provides smooth assembly and secure fastening in fine-thread applications
• Grade 5 strength classification delivers proven durability for heavy-duty industrial use
• External hex drive design allows for high-torque installation with standard tools
• Partially threaded configuration enables optimal clamping force distribution
• Rockwell C25 hardness maintains structural integrity under repeated stress

Professional Applications & Engineering Value

This Grade 5 hex head screw with 5/8"-18 UNF fine threading addresses critical engineering challenges in industrial assembly. The zinc plated steel construction provides essential corrosion protection for machinery, equipment, and structural applications exposed to harsh environments. The partially threaded design ensures maximum clamping force where needed while reducing material stress concentrations. With external hex drive compatibility, these screws accommodate high-torque installation requirements common in automotive, construction, and manufacturing sectors. The fine UNF thread pattern offers superior vibration resistance compared to coarse threads, making these fasteners ideal for precision equipment and dynamic load applications where secure, long-term fastening is paramount.

Specification Summary & Compliance

Manufactured to exacting Class 2A thread fit tolerances with 5/8"-18 UNF fine threading and 2 3/4" length. Complies with ASME B18.2.1 and SAE J429 Grade 5 specifications for dimensional accuracy and mechanical properties. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance standards, ensuring safe use across regulated industries.