S-91251A402 5/8"-18 x 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.
• Black-oxide coating on alloy steel provides corrosion resistance and a durable finish, extending service life in harsh industrial environments.
• Class 3A thread fit offers precise, tight tolerances for secure fastening and vibration resistance in critical assemblies.
• Fully threaded design allows for maximum grip and uniform load distribution along the entire length, enhancing holding power.
• Fine UNRF threads deliver improved clamping force and better resistance to loosening under dynamic loads compared to coarse threads.
• 1/2" hex drive socket head enables easy installation and removal with standard tools, saving time and labor in maintenance.
• Compliance with ASTM A574, RoHS 3, and REACH ensures adherence to industry standards and environmental regulations for safe, reliable 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 demanding environments. The fine UNRF thread and Class 3A fit provide superior thread engagement, minimizing backlash and maintaining clamp load in machinery, automotive, and heavy equipment applications. With a Rockwell C37 hardness and high tensile strength, it resists wear and deformation under heavy loads, ensuring long-term reliability. The fully threaded design offers consistent performance in assemblies requiring full-length fastening, while the black-oxide surface treatment adds an extra layer of protection against rust, making it ideal for outdoor or humid conditions. These features combine to reduce maintenance frequency and enhance operational safety in industrial screw applications.

Specification Summary & Compliance

This product features precise Class 3A thread fit with UNRF fine threads and a diameter of 0.625", ensuring accurate engagement and high strength. It meets ASTM A574 specifications for alloy steel socket head cap screws, guaranteeing consistent quality and performance. Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its suitability for environmentally conscious and safe industrial use without hazardous substances.