S-91251A077 2-56 x 1/4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating that protects against rust and extends service life in harsh industrial environments
• Exceptional mechanical strength with 170,000 psi tensile strength and Rockwell C37 hardness for reliable performance under high-stress applications
• Precision thread engagement with Class 3A fit ensuring tight tolerances and secure fastening in critical assemblies
• Optimized drive efficiency with standard hex socket (5/64" drive) design providing superior torque transmission and reduced cam-out risk
• Full thread coverage along the entire 1/4" length for maximum grip and load distribution across connected components
• Industry-standard compatibility with UNC coarse threads (2-56) ensuring interchangeability and easy replacement in existing systems
• Regulatory compliance assurance meeting ASTM A574, RoHS 3, and REACH standards for quality and environmental safety

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these black-oxide alloy steel socket head cap screws deliver exceptional performance where vibration resistance and mechanical reliability are critical. The UNC coarse thread design provides superior engagement in softer materials and faster installation times, while the Class 3A thread fit ensures precise alignment in precision machinery and electronic enclosures. The combination of 170,000 psi tensile strength and Rockwell C37 hardness makes these fully threaded screws ideal for high-stress applications in automotive assemblies, industrial equipment, and aerospace components where failure is not an option. The black-oxide surface treatment offers enhanced corrosion protection without dimensional changes, maintaining the socket head profile for consistent tool engagement throughout the product lifecycle.

Specification Summary & Compliance

Manufactured to exacting standards with Class 3A thread fit precision and UNC 2-56 thread specifications. These socket head cap screws comply with ASTM A574 manufacturing requirements for high-strength alloy steel fasteners. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring safe use across global industrial markets. The right-hand thread direction and coarse thread spacing provide industry-standard compatibility while maintaining dimensional accuracy across the 1/4" length and 0.086" thread diameter.