S-91274A181 1/4"-28 x 1" ASME B18.3, ASTM A574, ASTM B117 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in critical applications.
• Superior corrosion resistance provided by the zinc-flake coating, extending service life in harsh industrial environments and minimizing maintenance needs.
• Precision Class 3A thread fit guarantees tight tolerances and secure fastening, ideal for applications requiring vibration resistance and repeated assembly/disassembly.
• High hardness rating (Rockwell C37) enhances wear resistance and durability, maintaining thread integrity over extended use.
• Fine UNF thread design offers improved clamping force and better load distribution compared to coarse threads, suitable for precision engineering.
• Hex socket drive (3/16") allows for high torque application with standard tools, enabling efficient installation in confined spaces.
• Compliance with major standards including ASME B18.3 and ASTM A574 ensures consistent quality and interoperability in regulated industries.

Professional Applications & Engineering Value

This 1/4"-28 UNF socket head cap screw is engineered to address common industrial challenges such as vibration loosening, corrosion-induced degradation, and high-load demands. The zinc-flake-coated alloy steel construction provides a robust barrier against moisture and chemicals, making it ideal for automotive, aerospace, and heavy machinery applications where environmental resistance is critical. The fine thread Class 3A fit ensures minimal backlash and superior clamping force, preventing joint failure in dynamic systems. Its fully threaded design and right-hand thread direction facilitate easy alignment and secure fastening in precision assemblies, reducing installation time and enhancing operational reliability.

Specification Summary & Compliance

This socket head cap screw adheres to Class 3A thread fit per UNF standards, ensuring precise dimensional accuracy for fine thread applications. It meets ASME B18.3 for socket head dimensions, ASTM A574 for alloy steel material properties, and ASTM B117 for corrosion testing validation. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, confirming its suitability for global supply chains and eco-conscious manufacturing processes.