S-91257A830 5/8"-18 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 tensile strength of 150,000 psi ensures reliable performance in the most demanding heavy-duty applications, reducing the risk of fastener failure.
- Superior corrosion resistance from the zinc yellow-chromate plating protects against rust and degradation, extending service life in harsh industrial environments.
- High hardness rating (Rockwell C33) provides excellent wear resistance and durability, maintaining fastener integrity under high stress and vibration.
- Precision Class 2A thread fit and 5/8"-18 UNF fine thread design enable secure, tight fastening with reduced likelihood of loosening.
- External hex drive and hex head allow for easy installation and high torque application with standard tools, speeding up assembly processes.
- Partial threading offers an unthreaded shank for added shear strength, ideal for applications requiring precise clamp load and joint stability.
- Full compliance with industry standards including ASME B18.2.1 and SAE J429, ensuring consistent quality, interchangeability, and safety in regulated environments.
Professional Applications & Engineering Value
This Grade 8 hex head screw is engineered to address critical challenges in heavy-duty industrial applications, such as construction machinery, automotive assemblies, and structural frameworks. The zinc yellow-chromate plated steel construction combats corrosion in outdoor or chemically aggressive settings, while the 150,000 psi tensile strength and Rockwell C33 hardness prevent deformation under extreme loads. The 5/8"-18 UNF fine thread and Class 2A fit provide superior vibration resistance and clamping force, reducing maintenance needs. Its partially threaded design enhances shear resistance, making it a reliable choice for dynamic loads and high-stress joints where fastener integrity is paramount.
Specification Summary & Compliance
This screw adheres to inch system dimensions with a Class 2A thread fit for precise tolerance, manufactured per ASME B18.2.1 and SAE J429 specifications. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material restrictions are met for global industrial use.
