S-91255A521 1/4"-20 x 3/16" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with black-oxide coating, extending service life in demanding industrial environments.
• Superior torque transmission via the 5/32" hex drive, preventing tool slippage and ensuring secure installation.
• High tensile strength of 120,000 psi and Rockwell C39 hardness for reliable performance under heavy loads and vibration.
• Precise Class 3A thread fit ensures smooth engagement and reduces the risk of cross-threading in assembly lines.
• Fully threaded design provides consistent clamping force along the entire 3/16" length for uniform stress distribution.
• Coarse 1/4-20 UNC threading enables quick installation and superior resistance to loosening in high-vibration applications.
• Rounded button head profile offers a low-profile, aesthetically clean finish while minimizing snagging risks.

Professional Applications & Engineering Value

This black-oxide alloy steel screw is engineered to address critical challenges in industrial fastening, such as corrosion, vibration-induced failure, and assembly efficiency. The Class 3A thread fit and coarse UNC threading ensure rapid, reliable installation in machinery, automotive components, and structural assemblies, reducing downtime. The rounded head with hex drive allows for high-torque applications without damaging the fastener head, while the fully threaded design maximizes grip in thin materials. Ideal for heavy-duty fastening in manufacturing and equipment maintenance, it combines durability with compliance to major industry standards.

Specification Summary & Compliance

This screw adheres to ASME B18.3 and ASTM F835 specifications, ensuring dimensional accuracy and performance reliability. The 1/4-20 UNC coarse threads maintain a Class 3A fit for precise tolerance, while the material and coating meet RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance, supporting sustainable procurement practices.