S-91257A607 5/16"-18 x 4 1/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws
High-Strength Grade 8 Steel Hex Head Screws
Image may differ from product. See technical specification for details.
Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
- Fast delivery
- Enjoy discounts on bulk purchases
- Secure Payment
- Fast Global Shipping
Key Features & Benefits at a Glance
- Exceptional load-bearing capacity with 150,000 psi tensile strength for reliable performance in high-stress applications
- Superior corrosion resistance through zinc yellow-chromate plating that extends service life in harsh environments
- Optimized thread engagement with Class 2A thread fit ensuring consistent assembly and vibration resistance
- Enhanced durability from Rockwell C33 hardness providing excellent wear resistance and reduced deformation
- Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for quality assurance
- Efficient installation with external hex drive design allowing for high torque application and quick assembly
- Versatile partial threading combining threaded and unthreaded sections for optimal clamping force distribution
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers critical engineering solutions for industrial applications where structural integrity is paramount. The 5/16"-18 UNC coarse thread configuration provides superior holding power in soft materials and faster assembly times, while the zinc yellow-chromate plating creates a protective barrier against corrosion in outdoor or chemically aggressive environments. The partially threaded design ensures maximum clamping force concentration where needed, making it ideal for heavy machinery, structural steel connections, and construction applications requiring ASME B18.2.1 compliance. With its 150,000 psi tensile strength and Rockwell C33 hardness, this fastener maintains dimensional stability under extreme loads, preventing joint failure in critical assemblies.
Specification Summary & Compliance
Manufactured to precise dimensional standards with Class 2A thread fit tolerance for consistent performance. Complies with ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring mechanical properties and dimensional accuracy. Features UNC coarse threading (5/16"-18) with right-hand direction and 4 1/4" length with minimum 7/8" thread engagement. The external hex drive (1/2" width) accommodates standard wrenching tools for secure installation.
