S-91251A625 1 1/4"-12 x 5 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 harsh industrial environments.
• Precise torque application is enabled by the 7/8" hex drive and standard socket head, minimizing slippage and tool wear.
• Secure fastening in fine-thread applications due to the 1 1/4"-12 UNRF fine thread and Class 2A fit, providing excellent vibration resistance.
• Optimized for partial threading needs with a 3 1/8" minimum thread length, offering flexibility where full threading isn't required.
• High durability and hardness at Rockwell C37 ensures the screw maintains integrity under repeated loads and impacts.
• Compliance with global standards including ASTM A574, RoHS 3, and REACH assures material quality and environmental safety for international projects.

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 UNRF fine thread design enhances grip in materials prone to vibration loosening, while the partially threaded rod configuration allows for precise clamping without unnecessary threading. The high tensile strength of 170,000 psi and Rockwell C37 hardness provide resilience against dynamic loads, reducing maintenance downtime. Ideal for applications requiring corrosion-resistant fasteners, the black-oxide surface treatment combats moisture and chemical exposure, ensuring long-term reliability in demanding environments like manufacturing plants and outdoor infrastructure.

Specification Summary & Compliance

This socket head cap screw adheres to precise dimensional standards, including a Class 2A thread fit for consistent engagement and UNRF fine thread specifications. It meets ASTM A574 for material and manufacturing quality, ensuring high performance in critical applications. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free of hazardous substances and suitable for global supply chains.