S-91251A451 1/4"-28 x 2 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 tensile strength of 170,000 psi ensures reliable performance under high-stress applications
• Precision Class 3A thread fit provides superior engagement and vibration resistance in critical assemblies
• Fine UNRF threads offer improved load distribution and better sealing capabilities compared to coarse threads
• Hex socket drive design allows for high torque application and installation in confined spaces
• Consistent hardness (Rockwell C37) maintains dimensional stability and prevents stripping during repeated use
• Environmental compliance with RoHS 3 and REACH regulations ensures safe use across global markets

Professional Applications & Engineering Value

These black-oxide alloy steel socket head cap screws deliver critical performance advantages in precision engineering applications where failure is not an option. The combination of fine UNRF threads with Class 3A fit provides exceptional vibration resistance in machinery, automotive, and aerospace assemblies, preventing costly downtime from loosening fasteners. The partially threaded design allows for precise clamping force distribution, while the corrosion-resistant black-oxide finish protects against environmental degradation in harsh operating conditions. With their 170,000 psi tensile strength and hex socket drive, these fasteners withstand extreme mechanical stresses while enabling efficient installation in space-constrained applications, making them ideal for high-performance industrial equipment, precision instruments, and heavy machinery where reliability and durability are paramount.

Specification Summary & Compliance

Manufactured to ASTM A574 specifications, these socket head cap screws feature precision 1/4"-28 UNRF fine threads with Class 3A fit for superior dimensional accuracy. The 2 1/4" length with 1" minimum thread length provides consistent engagement, while the 3/16" hex drive ensures reliable torque transmission. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations confirms environmental responsibility and global market acceptance for industrial applications requiring certified components.