S-91251A918 1"-8 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.
• Superior corrosion resistance from the black-oxide finish on alloy steel extends service life in demanding industrial environments.
• Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant assemblies in critical machinery.
• 3/4" hex drive design allows for high-torque installation with standard tools, speeding up assembly and maintenance processes.
• Coarse UNRC 1"-8 threads enable quick engagement and disassembly, ideal for applications requiring frequent adjustments.
• Partially threaded shank offers optimal clamping force distribution, minimizing stress concentration on connected materials.
• Compliance with ASTM A574, RoHS 3, and REACH guarantees material consistency and environmental safety for global supply chains.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address common industrial challenges such as vibration loosening and corrosion-induced degradation. The Class 3A thread fit and coarse UNRC 1"-8 threads ensure rapid, secure fastening in heavy machinery, automotive assemblies, and construction equipment, where high tensile strength (170,000 psi) and Rockwell C37 hardness prevent stripping under extreme loads. The 3/4" hex drive facilitates efficient installation in confined spaces, reducing downtime. Ideal for partially threaded applications requiring precise clamping, it delivers long-term reliability in corrosive or high-stress environments, supported by ASTM A574 specifications for consistent performance.

Specification Summary & Compliance

This screw features a 1"-8 coarse UNRC thread with Class 3A fit for precision alignment, a minimum thread length of 2 1/2", and overall length of 3 1/2". Manufactured in accordance with ASTM A574 for material integrity, it is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring adherence to environmental and safety standards in industrial fastener applications.