S-91251A038 1/2"-20 x 8" 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
- Superior tensile strength of 170,000 psi ensures reliable performance under extreme loads, reducing the risk of fastener failure in critical applications.
- Precise Class 3A thread fit provides excellent engagement and vibration resistance, minimizing loosening in high-stress environments.
- Black-oxide coating on alloy steel offers enhanced corrosion resistance, extending service life in demanding industrial conditions.
- Fine UNRF thread profile allows for finer adjustments and better clamping force control compared to coarse threads.
- Partially threaded design concentrates strength where needed and facilitates easier alignment during assembly.
- Hex socket drive enables high torque application with standard tools, ensuring secure installations without stripping.
- Compliance with ASTM A574, RoHS 3, and REACH guarantees material consistency and environmental safety for global industrial use.
Professional Applications & Engineering Value
This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered to address common industrial challenges such as vibration-induced loosening and corrosion in machinery. The fine UNRF thread and Class 3A fit provide superior holding power in precision equipment, while the partially threaded shank reduces stress concentration points. Ideal for heavy-duty applications like automotive assemblies, construction machinery, and aerospace components, its high tensile strength and Rockwell C37 hardness ensure durability under cyclic loading. The black-oxide surface treatment further enhances resistance to wear and environmental exposure, making it a reliable choice for engineers seeking long-term fastener solutions.
Specification Summary & Compliance
This screw features a 1/2"-20 UNRF fine thread with Class 3A tolerance for precise fit, and a partially threaded rod type. It meets ASTM A574 specifications for alloy steel socket head cap screws, ensuring consistent material and mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting safe and sustainable industrial use.
