S-91251A597 5/16"-18 x 3 1/2" 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.
• Corrosion-resistant black-oxide coating on alloy steel enhances durability and longevity in harsh industrial environments.
• Precision Class 3A thread fit provides superior engagement and vibration resistance for secure, long-lasting assemblies.
• UNC coarse threading allows for quicker installation and easier alignment, saving time during assembly processes.
• Partially threaded design offers optimal clamping force control, ideal for applications requiring precise joint compression.
• 1/4" hex drive socket enables high-torque installation with standard tools, minimizing stripping and improving efficiency.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency, environmental safety, and suitability for regulated industries.

Professional Applications & Engineering Value

Engineered for demanding environments, this Black-Oxide Alloy Steel Socket Head Cap Screw delivers robust performance where precision and strength are critical. The UNC coarse thread and Class 3A fit provide excellent resistance to loosening under vibration, making it ideal for machinery, automotive assemblies, and heavy equipment. The partially threaded rod design ensures concentrated clamping force, reducing stress concentration points. With a Rockwell C37 hardness and 170,000 PSI tensile strength, it withstands extreme loads without deformation. The black-oxide surface treatment offers reliable corrosion protection, extending service life in humid or chemically exposed settings, while the 1/4" hex drive facilitates secure, high-torque fastening in confined spaces.

Specification Summary & Compliance

This screw adheres to Class 3A thread fit for precise dimensional accuracy and UNC coarse thread standards. It meets ASTM A574 specifications for high-strength alloy steel socket head cap screws, ensuring consistent manufacturing quality. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its suitability for use in environmentally conscious and regulated industrial applications.