S-91257A617 5/16"-24 x 3 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 demanding applications
• Superior corrosion resistance through zinc yellow-chromate plating in harsh environments
• Reliable thread engagement with Class 2A fit and UNF fine threads for vibration resistance
• High-strength Grade 8 construction with Rockwell C33 hardness for maximum durability
• Easy installation and removal with standard 1/2" external hex head design
• Optimized weight distribution through partial threading for structural applications
• Industry compliance assurance meeting ASME, SAE, RoHS 3 and REACH standards

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical performance in heavy machinery, construction equipment, and automotive assemblies where high tensile strength and vibration resistance are paramount. The 5/16"-24 UNF fine thread configuration provides superior clamping force retention in dynamic load conditions, while the zinc yellow-chromate plating offers extended service life in corrosive environments. The partially threaded design ensures optimal stress distribution across fastened joints, making it ideal for structural connections in industrial frameworks and mechanical systems requiring Grade 8 fasteners with proven reliability.

Specification Summary & Compliance

Manufactured to precise Class 2A thread fit tolerances with UNF thread form and 7/8" minimum thread length. Complies with ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance standards. Features Rockwell C33 hardness and 150,000 psi tensile strength consistent with Grade 8 requirements.