S-91257A812 5/8"-11 x 4 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 capability with Grade 8 classification and 150,000 psi tensile strength for demanding industrial applications
• Superior corrosion resistance through zinc yellow-chromate plating that protects against harsh environmental conditions
• Optimized thread engagement with UNC coarse thread design and Class 2A fit ensuring reliable fastening in various materials
• Enhanced durability from Rockwell C33 hardness that maintains structural integrity under repeated stress
• Efficient installation and removal with external hex drive and 15/16" head width for standard tool compatibility
• Versatile partial threading allowing for both clamping and alignment functions in assembly operations
• Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for quality assurance

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions for heavy machinery, structural frameworks, and industrial equipment where failure is not an option. The 5/8"-11 UNC coarse thread configuration provides superior resistance to vibration loosening while maintaining excellent shear strength. Manufactured from high-strength steel with zinc yellow-chromate plating, these fasteners combat corrosion in challenging environments from manufacturing plants to outdoor installations. The partially threaded design allows for precise clamping force distribution, making them ideal for applications requiring both secure fastening and component alignment. With 150,000 psi tensile strength and Rockwell C33 hardness, these screws maintain performance integrity in high-stress applications including construction equipment, automotive assemblies, and heavy-duty industrial machinery.

Specification Summary & Compliance

This heavy-duty fastener features Class 2A thread fit tolerance ensuring consistent engagement and proper clearances. The 5/8"-11 UNC coarse thread follows standardized dimensions with 4 1/2" length and 1 1/2" minimum thread length. Manufacturing complies with ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and performance requirements. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global industrial markets.