S-91251A585 5/16"-18 x 1 1/4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating, extending service life in demanding industrial environments.
• Exceptional clamping force and load distribution from the 170,000 psi tensile strength, preventing joint failure under high stress.
• Precise, reliable engagement ensured by Class 3A thread fit, minimizing the risk of cross-threading and assembly errors.
• High-torque installation capability with the 1/4" hex drive and standard socket head, allowing for secure fastening in confined spaces.
• Optimized for rapid assembly using coarse UNC threads, which are less prone to fouling and faster to install than fine threads.
• Consistent performance and durability from Rockwell C37 hardness, providing excellent wear resistance for repeated use.
• Guaranteed material and manufacturing quality through compliance with ASTM A574, ensuring reliability for critical applications.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address common industrial challenges such as vibration loosening, corrosion, and high tensile stress. The 5/16"-18 UNC coarse thread provides quick assembly and superior holding power in materials like steel and cast iron, reducing installation time. The socket head design with a 1/4" hex drive allows for high torque application in tight spaces, making it ideal for machinery, automotive assemblies, and precision equipment. The black-oxide surface treatment offers a durable, mildly corrosion-resistant finish that withstands harsh environments without galling. Fully compliant with ASTM A574, this fastener delivers consistent performance in high-stress applications, ensuring long-term reliability and reduced maintenance costs.

Specification Summary & Compliance

This socket head cap screw features a 5/16"-18 UNC coarse thread with Class 3A fit, ensuring precise dimensional accuracy and reliable thread engagement. Manufactured from alloy steel to ASTM A574 specifications, it meets stringent requirements for material integrity and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its safety and environmental standards for global industrial use.