S-91251A401 1 1/4"-7 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 under extreme loads and prevents fastener failure in demanding applications.
• Superior corrosion resistance provided by the black-oxide finish on alloy steel, extending the screw's service life in harsh industrial environments.
• High hardness rating of Rockwell C37 offers excellent wear resistance and maintains thread integrity through repeated use and high-torque installation.
• Coarse UNC threading enables faster installation and provides superior resistance to vibration loosening compared to fine-thread alternatives.
• Partially threaded design allows for precise clamping force application and secure fastening in specific assembly configurations.
• Standard hex socket drive with 7/8" drive size accommodates common industrial tools for efficient installation and removal in confined spaces.
• Full regulatory compliance with RoHS 3 and REACH standards ensures environmental safety and global market acceptance for your projects.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these black-oxide alloy steel socket head cap screws deliver critical performance where standard fasteners fail. The combination of 170,000 psi tensile strength and Rockwell C37 hardness provides exceptional resistance to shear forces and material deformation in machinery, structural frames, and high-vibration equipment. The UNC coarse thread profile ensures rapid assembly while maintaining secure fastening in materials where fine threads might strip or fail. The black-oxide surface treatment creates a protective barrier against oxidation and corrosion, significantly extending service life in environments exposed to moisture, chemicals, or temperature variations. These socket head cap screws are particularly valuable in applications requiring flush mounting and high torque transmission, such as precision equipment, automotive assemblies, and industrial manufacturing systems where reliability is paramount.

Specification Summary & Compliance

This socket head cap screw features Class 2A thread fit for consistent assembly compatibility and meets ASTM A574 manufacturing specifications for high-strength alloy steel fasteners. The 1 1/4"-7 UNC coarse thread maintains standard inch system dimensions with a minimum thread length of 3 1/8" on a 4 1/4" overall length. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations ensures environmental safety and unrestricted use in global industrial markets.