S-91251A522 5/16"-18 x 7/16" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Superior tensile strength of 170,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Exceptional hardness (Rockwell C37) provides excellent wear resistance and durability, extending the screw's service life in demanding environments.
• Precision Class 3A thread fit guarantees tight tolerances and secure fastening, minimizing backlash and improving assembly accuracy.
• Black-oxide finish on alloy steel offers enhanced corrosion resistance, protecting against rust in various industrial conditions.
• Coarse UNC threads allow for quicker installation and are less prone to clogging with debris, speeding up assembly processes.
• Standard hex socket drive with 1/4" size enables easy installation in confined spaces using common tools, reducing labor time.
• Fully threaded design ensures consistent clamping force along the entire length, providing uniform load distribution.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered to address critical challenges in industrial settings, such as vibration loosening and environmental degradation. The coarse 5/16"-18 UNC threads with a Class 3A fit deliver precise engagement, reducing the risk of cross-threading and ensuring reliable connections in machinery, automotive assemblies, and heavy equipment. The alloy steel construction combined with the black-oxide surface treatment provides robust corrosion resistance, making it ideal for applications exposed to moisture or chemicals. Its high tensile strength and hardness prevent stripping and deformation under load, offering long-term stability in precision fastening tasks. These screws are commonly used in CNC machines, construction equipment, and aerospace components where durability and compliance with strict standards are paramount.

Specification Summary & Compliance

This socket head cap screw features a 5/16"-18 UNC coarse thread with a Class 3A thread fit for high precision and consistent performance. It adheres to ASTM A574 specifications for alloy steel socket head cap screws, ensuring material and manufacturing quality. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free from hazardous substances and safe for industrial use. Dimensions include a length of 7/16" and a drive size of 1/4", designed for reliable fastening in various engineering applications.