S-91257A857 3/4"-10 x 5 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 demanding applications
• Superior corrosion resistance through zinc yellow-chromate plating that protects against harsh industrial environments
• Optimized thread engagement with partial threading and Class 2A fit ensuring secure fastening and vibration resistance
• Enhanced torque transmission via external hex drive and 1 1/8" head width for easy installation with standard tools
• Proven material durability featuring Grade 8 steel with Rockwell C33 hardness for long-term structural integrity
• Industry-standard compatibility with UNC coarse threads meeting ASME B18.2.1 specifications for interchangeability
• Environmental compliance assurance through RoHS 3 and REACH adherence for responsible manufacturing standards

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions for heavy-duty industrial applications where failure is not an option. The 3/4"-10 UNC coarse thread configuration provides superior resistance to vibration loosening in machinery, structural steel connections, and equipment assembly. The zinc yellow-chromate plated finish creates a protective barrier against corrosion in challenging environments, extending service life while maintaining 150,000 psi tensile strength. The partial threading design concentrates strength where needed most, preventing thread stripping while the external hex drive ensures reliable torque application during installation. These steel fasteners solve common industrial challenges including joint integrity maintenance, environmental degradation resistance, and high-stress load distribution across critical connections.

Specification Summary & Compliance

Manufactured to precise inch system dimensions with Class 2A thread fit tolerance for consistent performance. The UNC coarse thread (3/4"-10) follows standardized threading specifications while the 5 1/2" length with 1 3/4" minimum thread length ensures proper engagement. Compliant with ASME B18.2.1 and SAE J429 Grade 8 standards for mechanical properties and dimensional requirements. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance regulations for restricted substances.