S-91251A598 5/16"-18 x 3 3/4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior thread fit with Class 3A tolerance provides precise engagement and vibration resistance, minimizing loosening in dynamic environments.
• Black-oxide finish on alloy steel offers enhanced corrosion resistance, extending service life in demanding industrial conditions.
• Hex socket drive design allows for high torque application and easy installation in confined spaces, improving assembly efficiency.
• Coarse UNC threads enable quick assembly and disassembly, saving time in maintenance and production workflows.
• Partially threaded shank provides optimal grip and clamping force where needed, enhancing joint stability.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety, meeting global industry standards.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered to address critical challenges in heavy-duty machinery, automotive assemblies, and precision equipment. The coarse UNC thread design resists cross-threading and facilitates rapid installation, while the Class 3A thread fit ensures minimal backlash in high-vibration settings. With a Rockwell C37 hardness and robust 170,000 psi tensile strength, it withstands extreme loads without deformation, making it ideal for structural frames, engine components, and industrial tools. The black-oxide surface treatment adds a protective layer against moisture and chemicals, prolonging fastener life in harsh environments. These features collectively reduce maintenance downtime and enhance operational reliability for B2B industrial applications.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including a Class 3A thread fit for tight tolerances and a 5/16"-18 UNC coarse thread profile. It is manufactured in compliance with ASTM A574 specifications for high-strength alloy steel fasteners. The product is confirmed to be RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring it meets environmental and safety regulations for industrial use.