S-91251A015 1/2"-13 x 4 1/4" 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.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use.
• Coarse UNRC threading allows for quicker installation and reduced cross-threading risks, saving time during assembly.
• Partially threaded design enables precise clamping force control, ideal for applications requiring specific grip lengths.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety, meeting global regulatory standards.

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 1/2"-13 coarse thread and Class 3A fit provide superior resistance to loosening under dynamic loads, while the 170,000 psi tensile strength and Rockwell C37 hardness ensure durability against impact and fatigue. The black-oxide surface treatment significantly enhances corrosion resistance, making it suitable for environments exposed to moisture, chemicals, or outdoor conditions. By combining high-strength materials with precise manufacturing per ASTM A574, these screws deliver reliable performance in applications demanding robust socket head fasteners that maintain clamp load and structural integrity over time.

Specification Summary & Compliance

This screw features a 1/2"-13 UNRC coarse thread with Class 3A tolerance for precise fit, a partially threaded rod with minimum thread length of 1 1/2", and is manufactured to ASTM A574 specifications. It complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) standards, ensuring environmental safety and material consistency for industrial use.