S-91257A601 5/16"-18 x 5 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
- Maximum load-bearing capability with Grade 8 classification and 150,000 psi tensile strength for critical structural applications
- Superior corrosion protection through zinc yellow-chromate plating that withstands harsh industrial environments
- Optimized thread engagement with UNC coarse threading and Class 2A fit ensuring reliable installation and vibration resistance
- Enhanced durability from Rockwell C33 hardness providing excellent wear resistance and long service life
- Secure fastening control via external hex drive design that accommodates standard wrenching tools
- Versatile partial threading allowing both clamping force and unthreaded shank strength where needed
- Regulatory compliance assurance meeting ASME, SAE, RoHS 3, and REACH standards for quality and environmental safety
Professional Applications & Engineering Value
Engineered for heavy-duty industrial applications, these Grade 8 hex head screws deliver exceptional performance where failure is not an option. The zinc yellow-chromate plated finish provides superior corrosion resistance in demanding environments, while the UNC coarse threads with Class 2A fit ensure rapid installation and reliable vibration resistance. The partially threaded design offers the dual advantage of maximum clamping force in the threaded section combined with the full shank strength in unthreaded areas. With 150,000 psi tensile strength and Rockwell C33 hardness, these 5/16"-18 hex head screws maintain structural integrity under extreme loads, making them ideal for machinery assembly, construction equipment, and industrial frameworks requiring high-strength fastening solutions.
Specification Summary & Compliance
This 5/16"-18 hex head screw features precise Class 2A thread fit tolerances with UNC coarse threading and 5-1/2" length. Manufactured to ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring dimensional accuracy and mechanical performance. The fastener is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, guaranteeing safe use across industrial sectors while maintaining the highest quality standards for professional applications.
