S-91257A603 5/16"-18 x 5" 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 tensile strength of 150,000 PSI ensures reliable performance in high-stress applications, reducing the risk of fastener failure
- Superior corrosion resistance with zinc yellow-chromate plating protects against rust and environmental degradation in demanding industrial settings
- Precise Class 2A thread fit provides consistent engagement and reduces cross-threading issues during assembly
- Grade 8 hardness rating (Rockwell C33) delivers excellent durability and wear resistance for long service life
- Partial threading design offers optimal clamping force distribution while maintaining structural integrity
- External hex drive compatibility allows for standard tooling and efficient installation in confined spaces
- Comprehensive compliance with ASME, SAE, RoHS 3 and REACH standards ensures quality and environmental responsibility
Professional Applications & Engineering Value
Engineered for heavy-duty industrial applications, these Grade 8 hex head screws provide critical solutions for structural assemblies requiring maximum reliability. The 5/16"-18 UNC coarse thread configuration delivers superior vibration resistance in machinery, automotive, and construction applications where high tensile strength is paramount. The zinc yellow-chromate plated steel construction addresses corrosion concerns in harsh environments, while the partial threading design prevents joint loosening under dynamic loads. These external hex drive fasteners enable quick installation with standard tools, reducing assembly time and maintenance costs in production environments where downtime is critical.
Specification Summary & Compliance
This 5/16"-18 UNC hex head screw features Class 2A thread fit tolerance for precise engagement and meets ASME B18.2.1 and SAE J429 Grade 8 specifications. The fastener maintains dimensional accuracy with 5" length and 7/8" minimum thread length. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations ensures environmental responsibility and workplace safety standards are fully met.
