S-91257A610 5/16"-24 x 1 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional strength and reliability with Grade 8 classification, ensuring dependable performance in high-stress applications
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh industrial environments
• Precise thread engagement with Class 2A fit and UNF fine threading for secure, vibration-resistant connections
• Optimized torque transmission through external hex drive design, allowing for easy installation with standard tools
• Enhanced durability from Rockwell C33 hardness and 150,000 psi tensile strength, resisting deformation under heavy loads
• Versatile partial threading enabling both secure clamping and alignment flexibility in assembled components
• Regulatory compliance assurance meeting ASME B18.2.1, SAE J429, RoHS 3, and REACH standards for quality and safety

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver critical engineering value in demanding applications where failure is not an option. The steel construction with Rockwell C33 hardness provides exceptional resistance to shear and tensile stresses, making them ideal for heavy machinery, structural frameworks, and automotive assemblies. The zinc yellow-chromate plating creates a protective barrier against corrosion in outdoor or chemically aggressive environments, significantly reducing maintenance frequency. With 5/16"-24 UNF fine threading and Class 2A thread fit, these fasteners ensure precise engagement that resists loosening under vibration - a common challenge in industrial equipment. The partially threaded design allows for both secure clamping in the threaded section and clearance in the shank area, providing engineers with flexibility in component design while maintaining the 150,000 psi tensile strength required for critical connections.

Specification Summary & Compliance

These hex head screws feature precise Class 2A thread fit with UNF (Unified National Fine) threading standard, ensuring consistent engagement and interchangeability. Manufacturing complies with ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. The fasteners are fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, containing no restricted substances. With 1-3/4" length and 7/8" minimum thread length, these screws maintain dimensional consistency across production batches for reliable performance in industrial applications.