S-91257A702 7/16"-20 x 2 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 150,000 psi tensile strength for reliable performance in high-stress applications
• Superior corrosion resistance through zinc yellow-chromate plating that extends service life in harsh environments
• Precise thread engagement with Class 2A UNF fine threads ensuring secure fastening and vibration resistance
• Optimized torque transmission via external hex drive design for easy installation with standard tools
• Enhanced durability from Rockwell C33 hardness that maintains structural integrity under repeated stress
• Versatile partial threading allowing both secure clamping and adjustment flexibility in assembly applications
• Heavy-duty construction meeting Grade 8 specifications for the most demanding industrial fastening requirements

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver critical performance where failure is not an option. The 7/16-20 UNF fine threading provides superior resistance to vibrational loosening compared to coarse threads, while the partial threading design allows unthreaded shank sections to bear shear loads directly. The zinc yellow-chromate plating creates a robust barrier against corrosion in manufacturing environments exposed to moisture, chemicals, or outdoor conditions. Engineered for heavy machinery, structural steel connections, automotive assemblies, and industrial equipment, these external hex drive fasteners combine maximum 150,000 psi tensile strength with practical installation advantages. The Rockwell C33 hardness ensures the fastener maintains its mechanical properties even under extreme cyclic loading conditions common in industrial applications.

Specification Summary & Compliance

Manufactured to exacting Class 2A thread fit tolerances with 7/16-20 UNF fine threading and partial threading configuration. These hex head screws comply with ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring dimensional accuracy and mechanical performance. The fasteners are fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, making them suitable for global industrial applications with strict material restrictions.