S-91257A808 5/8"-11 x 3 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 provided by zinc yellow-chromate plating for extended service life in harsh environments
• Optimized torque transmission through external hex drive design ensuring secure installation and removal
• Enhanced thread engagement with Class 2A thread fit and UNC coarse threads for faster assembly and reduced cross-threading risk
• Grade 8 reliability with Rockwell C33 hardness maintaining structural integrity under heavy loads and vibration
• Partial threading design allowing for precise clamping force distribution in structural connections
• Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for guaranteed interchangeability

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions for heavy machinery, structural steel connections, and industrial equipment assembly. The 5/8"-11 UNC coarse thread configuration ensures rapid installation in thick materials while maintaining vibration resistance. The zinc yellow-chromate plating provides superior protection against corrosion in outdoor and chemical-exposed environments, significantly extending maintenance intervals. With partial threading and 3 1/2" length, this fastener offers optimal unthreaded shank strength where maximum clamping force is required. The external hex drive accommodates standard tools for efficient installation in confined spaces, making it ideal for construction, manufacturing, and transportation equipment where high-strength fasteners are essential for safety and performance.

Specification Summary & Compliance

Manufactured to precise Class 2A thread fit tolerances with UNC coarse threading (5/8"-11) and partial threading configuration. Complies with ASME B18.2.1 and SAE J429 Grade 8 specifications for dimensional accuracy and mechanical properties. Meets environmental regulations including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance standards. Features Rockwell C33 hardness and 150,000 psi minimum tensile strength as per Grade 8 requirements.