S-91257A464 3/8"-24 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 - Grade 8 classification and 150,000 psi tensile strength ensure reliable performance in high-stress applications, reducing failure risks.
• Superior Corrosion Protection - Zinc yellow-chromate plating provides enhanced resistance to rust and environmental degradation, extending service life in harsh conditions.
• Precise Thread Engagement - Class 2A thread fit and 3/8"-24 UNF fine threading offer consistent, secure fastening with reduced vibration loosening.
• Optimized Torque Application - External hex drive and 9/16" head width allow for high torque installation using standard tools, improving assembly efficiency.
• Controlled Thread Distribution - Partial threading design concentrates threads where needed, providing stronger grip in critical sections while minimizing weight.
• Industry Standard Compliance - Meets ASME B18.2.1 and SAE J429 specifications, ensuring interchangeability and reliability across industrial systems.
• Environmental Responsibility - RoHS 3 and REACH compliance guarantees safe use in regulated industries while maintaining performance standards.

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions for heavy machinery, construction equipment, and automotive assemblies where high tensile strength and vibration resistance are paramount. The 3/8"-24 UNF fine thread configuration maintains clamping force under dynamic loads, while the zinc yellow-chromate plating protects against corrosion in outdoor or chemically exposed environments. The partially threaded design provides optimal stress distribution, making it ideal for structural connections requiring precise unthreaded shank sections. With Rockwell C33 hardness and external hex drive, it withstands repeated torque applications without deformation, reducing maintenance cycles in industrial fastener systems.

Specification Summary & Compliance

Manufactured to Class 2A thread fit tolerances with 3/8"-24 UNF fine threading and 1" minimum thread length. Complies with ASME B18.2.1 and SAE J429 standards for dimensional accuracy and mechanical properties. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance requirements. The 3 3/4" length and partial threading provide versatile application coverage while maintaining Grade 8 performance characteristics.