S-91257A657 3/8"-24 x 1 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 capability with 150,000 psi tensile strength for demanding structural and mechanical applications.
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh industrial environments.
• High hardness rating of Rockwell C33 ensures excellent wear resistance and durability under repetitive stress.
• Reliable fine thread engagement with 3/8"-24 UNF and Class 2A fit for secure, vibration-resistant fastening in precision assemblies.
• Optimized for high-torque installation using the external hex drive and hex head design, facilitating efficient assembly with standard tools.
• Controlled threading as partially threaded, allowing for focused clamping force where needed without unnecessary thread contact.
• Full compliance with industry standards including ASME B18.2.1 and SAE J429, ensuring interchangeability and performance reliability.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy machinery, automotive, and construction sectors where joint integrity is paramount. The zinc yellow-chromate plated steel construction combats oxidation and chemical exposure, reducing maintenance frequency in outdoor or corrosive settings. With a fine UNF thread and Class 2A thread fit, it delivers precise alignment and resistance to loosening under dynamic loads. The partial threading concentrates clamping force on specific sections, preventing thread damage in blind holes and enhancing assembly efficiency. Ideal for high-stress bolting applications, this fastener ensures long-term performance where vibration, tension, and environmental factors are concerns.

Specification Summary & Compliance

The screw adheres to Class 2A thread tolerance for consistent fit and meets ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free from hazardous substances and safe for industrial use. The 3/8"-24 UNF fine thread and 1-1/2" length provide standardized compatibility across equipment and assemblies.