S-91251A444 1/4"-28 x 1 1/4" ASTM A574 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 assemblies.
• Superior corrosion resistance from the black-oxide finish prolongs service life in harsh industrial environments, minimizing maintenance and replacement costs.
• Precise Class 3A thread fit guarantees tight, secure connections with minimal backlash, enhancing assembly accuracy and vibration resistance.
• High hardness (Rockwell C37) provides excellent wear resistance, maintaining thread integrity and drive engagement through repeated use.
• Fine UNRF thread spacing offers improved load distribution and finer adjustment capabilities compared to coarse threads, ideal for precision applications.
• Fully threaded design allows for consistent clamping force along the entire length, ensuring uniform pressure distribution in assembled components.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency, environmental safety, and global regulatory acceptance for worry-free procurement.

Professional Applications & Engineering Value

Engineered for demanding industrial environments, these Black-Oxide Alloy Steel Socket Head Cap Screws deliver outstanding performance in machinery, automotive, and aerospace assemblies where precision and durability are non-negotiable. The 1/4"-28 UNRF fine thread provides superior resistance to loosening under vibration, while the 3/16" hex drive offers high torque transmission without cam-out, ensuring secure fastening in confined spaces. The black-oxide surface treatment not only enhances corrosion resistance but also reduces galling during installation, extending tool life and assembly efficiency. With a fully threaded design and Class 3A fit, these screws maintain consistent preload in high-stress joints, making them ideal for critical applications requiring repeatable clamping force and long-term reliability.

Specification Summary & Compliance

This socket head cap screw features a 1/4"-28 UNRF fine thread with Class 3A thread fit for precision engagement, manufactured to ASTM A574 specifications for consistent quality. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and unrestricted use in global markets. Dimensions include a 3/16" hex drive, 1 1/4" length, and standard socket head profile, all conforming to inch system measurements for seamless integration with existing tooling and designs.