S-91670A716 1/2"-13 x 1 1/2" ASTM A574 Left-Hand Threaded 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 coating on alloy steel extends service life in harsh industrial environments.
• Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant assemblies in critical machinery.
• Left-hand UNC coarse threading offers optimal engagement for applications requiring reverse-threading to prevent loosening under counter-clockwise forces.
• High hardness (Rockwell C37) enhances wear resistance, maintaining thread integrity through repeated use.
• 3/8" hex drive design allows for easy installation with standard tools, improving assembly efficiency.
• Compliance with ASTM A574, RoHS 3, and REACH ensures 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-induced loosening and corrosion in demanding settings. Its left-hand UNC coarse thread and Class 3A fit provide superior clamping force in equipment like heavy machinery, automotive systems, and aerospace assemblies where reverse threading is critical. The high tensile strength and Rockwell C37 hardness ensure durability under dynamic loads, while the black-oxide coating offers added protection against rust and wear. Ideal for industrial fasteners requiring reliable, long-term performance, this screw minimizes maintenance needs and enhances operational safety in corrosive or high-stress environments.

Specification Summary & Compliance

This socket head cap screw meets precise dimensional standards with a Class 3A thread fit and UNC coarse threading for consistent engagement. It adheres to ASTM A574 specifications for material and manufacturing quality, ensuring high strength and reliability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its suitability for environmentally conscious industrial applications without restricted substances.