S-91257A809 5/8"-11 x 3 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Maximum Load-Bearing Capacity - Grade 8 classification and 150,000 psi tensile strength ensure reliable performance in high-stress industrial applications
• Superior Corrosion Protection - Zinc yellow-chromate plating provides enhanced resistance to rust and environmental degradation
• Optimized Thread Engagement - UNC coarse thread design with Class 2A fit guarantees secure fastening and easier installation in tough materials
• Exceptional Durability - Rockwell C33 hardness rating maintains structural integrity under repeated stress and vibration
• Enhanced Drive Efficiency - External hex head design allows for high-torque application with standard tools
• Versatile Partial Threading - 1½" minimum thread length on 3¾" overall length provides flexibility for various clamping requirements
• Regulatory Compliance Assurance - Meets multiple industry standards for quality and environmental safety

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these Grade 8 hex head screws deliver exceptional performance in construction, heavy machinery, and structural assemblies where failure is not an option. The zinc yellow-chromate plated steel construction provides superior corrosion resistance in harsh environments, while the UNC coarse thread pattern ensures reliable engagement in both soft and hard materials. The external hex drive design accommodates high torque applications, making these heavy-duty fasteners ideal for critical joints in equipment manufacturing, structural steel connections, and automotive assemblies where 150,000 psi tensile strength and Rockwell C33 hardness are essential for maintaining long-term structural integrity under dynamic loads.

Specification Summary & Compliance

This 5/8"-11 UNC hex head screw features Class 2A thread fit tolerance for precise engagement and is manufactured to exacting ASME B18.2.1 and SAE J429 specifications. The fastener maintains compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global markets. With partial threading and standardized dimensions, these industrial-grade bolts deliver consistent performance meeting international quality standards for high-strength fastening applications.