S-91257A666 3/8"-24 x 4 1/2" 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, extending service life in harsh industrial environments
- Precise thread engagement with Class 2A UNF fine threads ensuring secure fastening and vibration resistance
- Heavy-duty construction meeting Grade 8 standards with Rockwell C33 hardness for maximum durability
- Optimized drive efficiency with external hex head design providing excellent torque transmission during installation
- Versatile partial threading allowing for both clamping and alignment functions in complex assemblies
- Regulatory compliance assurance with RoHS 3 and REACH standards for global industrial applications
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 3/8"-24 UNF fine thread configuration provides superior resistance to vibrational loosening while maintaining precise clamping force. The zinc yellow-chromate plating creates a protective barrier against oxidation and chemical exposure, significantly extending maintenance intervals in demanding environments. With partial threading and external hex drive, this fastener offers optimal installation control for critical joints in construction, automotive, and manufacturing applications where reliability cannot be compromised.
Specification Summary & Compliance
Manufactured to exacting Class 2A thread fit tolerances with UNF fine thread specifications ensuring precision mating with corresponding components. Complies with ASME B18.2.1 and SAE J429 standards for dimensional accuracy and mechanical properties. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance requirements for environmental safety and restricted substance control. The inch system measurements maintain consistency with North American industrial standards while the Grade 8 classification guarantees consistent performance across production batches.
