S-91251A398 1 1/8"-7 x 5 1/2" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi provides reliable performance under extreme loads, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance from the Black-Oxide finish on Alloy Steel, extending service life and maintaining integrity in harsh industrial environments.
• High torque capability with a large 7/8" Hex Drive, ensuring secure installation and removal without stripping, even in high-vibration settings.
• Optimized thread design with coarse UNRC threads and Class 2A fit for faster assembly and reduced cross-threading, saving valuable production time.
• Enhanced durability from Rockwell C37 hardness, offering excellent wear resistance and long-term reliability for heavy-duty mechanical assemblies.
• Versatile partial threading allows for precise clamping force control, ideal for applications requiring specific unthreaded shaft sections.
• Regulatory compliance with RoHS 3 and REACH ensures environmental safety and global market acceptance for your products.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered to address critical challenges in heavy machinery, construction equipment, and high-stress automotive assemblies. Its coarse UNRC thread and Class 2A fit facilitate rapid installation in thick materials, minimizing assembly time while preventing thread galling. The partially threaded design provides a smooth shank for precise bearing surfaces, reducing stress concentrations in dynamic load applications. With a 170,000 psi tensile strength and Rockwell C37 hardness, it resists fatigue and impact forces in vibrating environments, ensuring joint integrity. The black-oxide surface treatment adds a protective layer against oxidation and mild chemicals, making it suitable for outdoor and industrial settings where corrosion can compromise safety and performance.

Specification Summary & Compliance

This socket head cap screw features a 1 1/8"-7 UNRC coarse thread with Class 2A tolerance for consistent fit and ease of assembly. It is manufactured in accordance with ASTM A574 specifications, ensuring material quality and dimensional accuracy. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its adherence to environmental and safety standards for hazardous substances.