S-91257A555 1/4"-20 x 3 1/4" 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 through zinc yellow-chromate plating, extending service life in harsh environments
- Enhanced durability with Rockwell C33 hardness, maintaining structural integrity under repeated stress
- Secure fastening performance with Class 2A thread fit and UNC coarse threads for vibration resistance
- Optimized torque transmission through external hex drive design, enabling efficient installation with standard tools
- Partial threading design providing both gripping strength and clearance where needed
- Industry compliance assurance meeting ASME B18.2.1 and SAE J429 standards for quality and reliability
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers critical engineering solutions for industrial applications demanding uncompromising strength and reliability. The steel construction combined with zinc yellow-chromate plating creates a robust barrier against corrosion, making it ideal for machinery, structural assemblies, and equipment exposed to demanding environmental conditions. The 1/4"-20 UNC coarse thread configuration ensures rapid installation and superior resistance to vibration loosening, while the partially threaded design provides optimal clamping force distribution. These heavy-duty hex screws are engineered to maintain integrity in high-stress applications where fastener failure is not an option, from industrial machinery to construction equipment and automotive assemblies.
Specification Summary & Compliance
This fastener maintains precise Class 2A thread fit tolerances with 1/4"-20 UNC coarse thread specifications. Manufacturing complies with ASME B18.2.1 and SAE J429 Grade 8 standards, ensuring consistent quality and performance. The product is fully RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting current environmental regulations for industrial use.
