S-91257A604 5/16"-18 x 6 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, ideal for high-stress industrial applications
• Superior corrosion resistance through zinc yellow-chromate plating, extending service life in harsh environments
• Reliable thread engagement with UNC coarse threading and Class 2A fit, ensuring secure fastening in various materials
• Optimized torque transmission through external hex drive design, enabling efficient installation with standard tools
• Enhanced durability with Rockwell C33 hardness, maintaining structural integrity under repeated stress
• Versatile partial threading allowing both clamping and alignment functions in assembly operations
• Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for quality assurance

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver critical performance in demanding applications where failure is not an option. The steel construction combined with zinc yellow-chromate plating creates a robust barrier against corrosion in industrial environments, from manufacturing equipment to structural assemblies. The UNC coarse thread design provides excellent engagement in both metals and composites, while the partial threading allows for precise clamping force distribution. With 150,000 psi tensile strength and Rockwell C33 hardness, these heavy-duty hex bolts maintain integrity under vibration and dynamic loads, making them ideal for machinery, construction, and transportation applications requiring reliable fastening solutions that meet rigorous industry standards.

Specification Summary & Compliance

Manufactured to precise dimensional standards with Class 2A thread fit tolerance for consistent performance. The 5/16"-18 UNC coarse thread configuration ensures proper engagement while the 6 1/2" length with 1 1/8" minimum thread length provides versatile fastening options. These hex head screws fully comply with ASME B18.2.1 and SAE J429 specifications, guaranteeing dimensional accuracy and mechanical properties. The external hex drive with 1/2" head width accommodates standard wrenching tools for efficient installation in industrial settings.