S-91257A706 7/16"-20 x 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 reliable performance in high-stress applications
- Superior corrosion resistance through zinc yellow-chromate plating that extends service life in demanding environments
- Precise thread engagement with Class 2A UNF fine threads ensuring secure fastening and vibration resistance
- Optimized torque transmission via external hex drive design that prevents tool slippage during installation
- Enhanced durability from Rockwell C33 hardness that maintains structural integrity under repeated stress
- Versatile partial threading allowing both clamping and alignment functions in assembly operations
- Regulatory compliance assurance meeting ASME, SAE, RoHS 3 and REACH standards for global industrial use
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers critical engineering solutions for heavy machinery, structural frameworks, and industrial equipment where high tensile strength and corrosion resistance are paramount. The 7/16-20 UNF fine thread configuration provides superior resistance to vibrational loosening compared to coarse threads, while the zinc yellow-chromate plating creates a protective barrier against chemical exposure and environmental factors. The partially threaded design allows the unthreaded shank to bear shear loads efficiently, making it ideal for pinned connections and precision alignment applications. With its external hex drive and substantial 5/8" head width, installers achieve higher torque values without damaging the fastener head, reducing installation time and maintenance costs in industrial settings.
Specification Summary & Compliance
Manufactured to ASME B18.2.1 and SAE J429 specifications with Class 2A thread fit tolerance ensuring consistent threading quality. The 4" length with 1 1/8" minimum thread length provides optimal engagement depth. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations for safe use across international markets.
