S-91251A506 5/8"-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 under extreme loads, reducing the risk of fastener failure in demanding applications.
• Precise Class 3A thread fit provides superior engagement and vibration resistance, minimizing loosening in high-stress environments.
• Black-oxide coating on alloy steel offers enhanced corrosion resistance and a durable, non-reflective finish for long-term use.
• Rockwell C37 hardness delivers excellent wear resistance and durability, extending the screw's service life in repetitive assembly operations.
• 1/2" hex drive design allows for high torque application and secure installation, improving efficiency in maintenance and manufacturing.
• Partially threaded UNF fine thread enables precise clamping control and reduced cross-threading risks in critical assemblies.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety for global industrial standards.

Professional Applications & Engineering Value

These black-oxide alloy steel socket head cap screws are engineered to address common industrial challenges such as vibration-induced loosening and material fatigue. The UNF fine thread configuration, combined with a Class 3A fit, ensures tight tolerances and reliable performance in machinery, automotive, and heavy equipment applications where precision and strength are critical. The partially threaded design allows for focused stress distribution, reducing the risk of thread stripping in high-clamp force scenarios. With a Rockwell C37 hardness and 170,000 psi tensile strength, these screws withstand repetitive loads and harsh conditions, making them ideal for assembly lines, structural frames, and precision engineering projects that demand durability and compliance with ASTM A574 specifications.

Specification Summary & Compliance

This socket head cap screw features a 5/8"-18 UNF fine thread with Class 3A thread fit for high precision and minimal backlash. Dimensions include a 3 3/4" length, 15/16" head diameter, and 1 3/4" minimum thread length. Manufactured in accordance with ASTM A574 standards, it ensures consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting environmentally responsible and safe industrial use.