S-91257A596 5/16"-18 x 2 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws
High-Strength Grade 8 Steel Hex Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Exceptional load-bearing capacity with 150,000 psi tensile strength for critical structural applications
- Superior corrosion protection through zinc yellow-chromate plating that withstands harsh industrial environments
- Optimized torque transmission via external hex drive design that prevents tool slippage during installation
- Reliable thread engagement with UNC coarse threads that resist vibration loosening in heavy machinery
- Precision manufacturing ensuring Class 2A thread fit for consistent assembly performance
- Enhanced durability from Rockwell C33 hardness that maintains integrity under repeated stress
- Versatile partial threading allowing both clamping and alignment functions in complex assemblies
Professional Applications & Engineering Value
Engineered for demanding industrial applications, these Grade 8 hex head screws deliver exceptional performance in construction equipment, heavy machinery, and structural frameworks. The 5/16"-18 UNC coarse thread design provides superior resistance to vibration-induced loosening, while the zinc yellow-chromate plating creates a robust barrier against corrosion in outdoor or chemically aggressive environments. The partially threaded configuration offers dual functionality - the unthreaded shank maintains precise alignment in bolted joints, while the threaded portion ensures secure fastening. With 150,000 psi tensile strength and Rockwell C33 hardness, these screws maintain structural integrity under extreme loads, making them ideal for critical connections where failure is not an option.
Specification Summary & Compliance
Manufactured to exacting standards with Class 2A thread fit tolerance and UNC coarse thread specifications. Fully compliant with ASME B18.2.1 and SAE J429 Grade 8 requirements for dimensional accuracy and mechanical properties. Meets environmental regulations including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance. The inch system measurement ensures compatibility with North American industrial equipment and replacement part specifications.
