S-91257A451 5/16"-24 x 6 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 provided by zinc yellow-chromate plating, extending service life in harsh environments
- Precise thread engagement with Class 2A UNF fine threads ensuring secure, vibration-resistant connections
- Optimized strength-to-weight ratio through Grade 8 steel construction with Rockwell C33 hardness
- Easy installation and removal with standard external hex drive and 1/2" head width for common tool compatibility
- Reduced material stress concentration through partial threading design while maintaining 1 1/8" minimum thread length
- Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for guaranteed interchangeability
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers critical performance where high tensile strength and corrosion resistance are paramount. The zinc yellow-chromate plated steel construction provides exceptional protection against environmental degradation, while the 5/16"-24 UNF fine thread configuration ensures superior vibration resistance in dynamic applications. The partially threaded design concentrates strength where needed most, making it ideal for heavy-duty industrial equipment, machinery assembly, structural frameworks, and automotive applications requiring 150,000 psi tensile strength. The external hex drive with substantial 1/2" head width accommodates standard tools for efficient installation in confined spaces.
Specification Summary & Compliance
Manufactured to exacting ASME B18.2.1 and SAE J429 specifications, this fastener features precision Class 2A thread fit with UNF fine threading (5/16"-24) and right-hand thread direction. The 6 1/2" length with 1 1/8" minimum thread length provides optimal engagement characteristics. Grade 8 strength classification is verified through Rockwell C33 hardness testing and 150,000 psi tensile strength validation. The zinc yellow-chromate plating meets industry standards for corrosion protection while maintaining dimensional integrity.
