S-91257A850 3/4"-10 x 3 3/4" 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, extending service life in harsh environments
• Optimized mechanical properties with Rockwell C33 hardness ensuring excellent wear resistance and durability
• Secure fastening engagement through Class 2A thread fit and coarse UNC threading for vibration resistance
• Easy installation and removal with external hex drive design and 1 1/8" head width for standard tool compatibility
• Partial threading design allows for precise clamping force distribution and reduced thread damage risk
• Full regulatory compliance meeting ASME, SAE, RoHS 3, and REACH standards for global industrial use

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver critical engineering solutions for heavy machinery, structural steel connections, and industrial equipment assembly. The 3/4"-10 UNC coarse thread configuration provides superior resistance to vibration loosening while enabling rapid installation in demanding environments. The zinc yellow-chromate plating creates a protective barrier against corrosive elements in manufacturing facilities, construction sites, and outdoor applications. With partial threading design, these fasteners optimize clamping force distribution while minimizing thread wear during repeated disassembly. The combination of 150,000 psi tensile strength and Rockwell C33 hardness ensures reliable performance in high-torque applications where fastener failure is not an option, making them ideal for critical connections in construction, automotive, and heavy equipment industries.

Specification Summary & Compliance

Manufactured to precise Class 2A thread fit tolerances with 3/4"-10 UNC coarse threading meeting ASME B18.2.1 and SAE J429 specifications. These partially threaded hex head screws feature a 1 1/8" head width and 1/2" head height for standard tool compatibility. Full compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations ensures safe use across global markets. The Grade 8 classification guarantees consistent mechanical properties and performance reliability for industrial applications requiring certified high-strength fasteners.