S-91251A117 3/8"-16 x 8" 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 industrial applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the black-oxide finish on alloy steel extends service life in harsh environments, minimizing maintenance needs.
• Precise Class 3A thread fit provides tight, secure connections with reduced vibration loosening, enhancing assembly integrity.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use and adjustments.
• Coarse UNRC threads allow for quicker installation and better performance in materials prone to debris or galling.
• Hex socket drive design enables high torque application with standard tools, facilitating efficient assembly and disassembly.
• Compliance with ASTM A574, RoHS 3, and REACH ensures consistent quality and environmental safety for global industrial use.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered to address critical challenges in heavy-duty machinery, automotive, and construction sectors. Its high tensile strength and Rockwell C37 hardness prevent stripping and deformation under extreme loads, while the black-oxide surface treatment provides a durable barrier against rust and corrosion in humid or chemical-exposed environments. The Class 3A thread fit and coarse UNRC threads ensure rapid, secure fastening in assemblies where precision and vibration resistance are paramount, such as engine components, structural frames, and industrial equipment. By combining robust material properties with standardized dimensions, this screw delivers reliable fastening solutions that reduce downtime and maintenance costs.

Specification Summary & Compliance

This socket head cap screw features a 3/8"-16 thread size with Class 3A fit and coarse UNRC thread type, ensuring precise dimensional accuracy per industry standards. It complies with ASTM A574 for material and manufacturing consistency, and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations for environmental safety. The screw is partially threaded with a minimum thread length of 1 1/4", and its mechanical properties, including tensile strength and hardness, are rigorously controlled to support demanding applications.