S-91251A318 5/16"-18 x 5 3/4" ASTM A574 Alloy Steel Socket Head Screws
Alloy Steel Socket 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 170,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
- Superior corrosion resistance from the black-oxide finish on alloy steel, extending service life and maintaining integrity in harsh industrial environments.
- Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant assemblies, minimizing loosening in critical machinery.
- High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity and drive performance through repeated use.
- Hex socket drive design allows for high-torque installation with standard 1/4" tools, enabling efficient assembly in confined spaces.
- Partially threaded shank provides unthreaded bearing surface for better clamping force distribution, ideal for precision joint applications.
- Compliance with ASTM A574, RoHS 3, and REACH ensures material quality and environmental safety, meeting global industrial standards.
Professional Applications & Engineering Value
These black-oxide alloy steel socket head cap screws deliver critical engineering solutions where high tensile strength and corrosion resistance are paramount. The 5/16"-18 UNC coarse thread with Class 3A fit ensures secure fastening in vibrating equipment, while the partially threaded design prevents thread damage during assembly and improves clamp load distribution. Ideal for heavy-duty industrial applications including machinery frames, automotive components, and precision equipment, these screws withstand extreme forces without compromising thread integrity. The hex drive facilitates easy installation in tight spaces, reducing assembly time and maintenance costs in production environments.
Specification Summary & Compliance
Manufactured to ASTM A574 specifications with Class 3A thread fit and UNC coarse thread profile. Dimensions include 5/16"-18 thread size, 5 3/4" length, and 1/4" hex drive. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use in global markets.
