S-91251A560 1/4"-20 x 1 1/8" 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 corrosion resistance from the black-oxide finish extends service life in harsh industrial environments, minimizing maintenance needs.
• Precise Class 3A thread fit provides secure, vibration-resistant connections, enhancing assembly integrity and reducing loosening over time.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use and installation.
• Hex socket drive design allows for easy installation in confined spaces with standard tools, improving assembly efficiency.
• Coarse UNRC threads enable quick engagement and reduced cross-threading risk, speeding up production and repair processes.
• Full threading along the 1-1/8" length provides consistent clamping force and flexibility in adjustment for various material thicknesses.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical challenges in heavy-duty industrial settings, such as machinery assembly, automotive systems, and construction equipment. The high-strength alloy steel combined with a black-oxide surface treatment delivers robust corrosion resistance, preventing degradation in humid or chemically aggressive environments. Its Class 3A thread fit and coarse UNRC threads ensure tight, reliable fastening that withstands vibrations and dynamic loads, reducing downtime from loosened connections. Ideal for applications demanding superior tensile strength and durability, this fastener supports long-term operational safety and efficiency in sectors like manufacturing, aerospace, and energy infrastructure.

Specification Summary & Compliance

This socket head cap screw adheres to precise dimensional standards, including a Class 3A thread fit for tight tolerances and UNRC coarse threads with a 1/4"-20 size. It meets ASTM A574 specifications for high-strength requirements and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and regulatory adherence for global industrial use.