S-91251A941 1 1/4"-7 x 4 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 under extreme loads, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance provided by the black-oxide finish on alloy steel, extending service life in harsh industrial environments.
• High torque capability with a 7/8" hex drive and standard socket head profile for secure installation and removal, minimizing tool slippage.
• Optimized thread engagement through coarse 1 1/4"-7 UNRC threads and Class 2A fit, enabling quick assembly and vibration resistance.
• Versatile partial threading design allows for precise clamping force control and is ideal for applications requiring a non-threaded shank section.
• Consistent hardness at Rockwell C37 ensures durability and wear resistance, maintaining dimensional stability over repeated use.
• Compliance with global standards including ASTM A574, RoHS 3, and REACH, ensuring material safety and reliability for international industrial use.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical challenges in heavy machinery, automotive, and construction sectors where high tensile strength and corrosion protection are paramount. The coarse thread (1 1/4"-7 UNRC) and Class 2A thread fit provide excellent grip and rapid installation, reducing assembly time while resisting loosening under vibration. The partially threaded design offers flexibility in joint design, allowing engineers to apply clamping force precisely without thread interference. With a 170,000 psi tensile strength and Rockwell C37 hardness, it withstands dynamic loads and harsh conditions, making it a reliable choice for structural frames, industrial equipment, and high-stress fastening applications where durability and compliance with ASTM A574 standards are essential.

Specification Summary & Compliance

This socket head cap screw features a 1 1/4"-7 coarse thread with Class 2A thread fit for precise dimensional accuracy and easy assembly. It adheres to ASTM A574 specifications for high-strength alloy steel fasteners and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material reliability in industrial use.