S-91286A128 1/4"-20 x 3" 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-flake coating, extending service life in harsh industrial environments
- Enhanced torque transmission through external hex drive design for secure installation and removal
- Optimized thread engagement with UNC coarse thread pattern ensuring strong holding power and vibration resistance
- Precision thread fit meeting Class 2A specifications for consistent assembly and reduced cross-threading risks
- Grade 8 reliability with Rockwell C33 hardness maintaining structural integrity under heavy loads
- Versatile partial threading allowing for both clamping and alignment functions in various assembly scenarios
Professional Applications & Engineering Value
Engineered for demanding industrial applications, these Grade 8 hex head screws deliver exceptional performance in construction, heavy machinery, and automotive assemblies. The zinc-flake coated steel construction provides superior corrosion protection, significantly extending service life in challenging environments where moisture and chemicals are present. The 1/4"-20 UNC coarse thread design ensures rapid installation and superior resistance to vibration loosening, while the partial threading allows for precise clamping force distribution. With 150,000 psi tensile strength and Rockwell C33 hardness, these fasteners maintain structural integrity under extreme loads, making them ideal for critical connections in structural frameworks, equipment mounts, and high-stress mechanical assemblies where failure is not an option.
Specification Summary & Compliance
This heavy-duty hex head screw features precise Class 2A thread fit with 1/4"-20 UNC coarse thread specifications and 3/4" minimum thread length. Manufactured to ASME B18.2.1 and SAE J429 Grade 8 standards, ensuring dimensional accuracy and mechanical properties. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, making them suitable for global industrial applications requiring strict regulatory adherence.
