S-91251A523 4-40 x 1 1/8" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating, ideal for harsh industrial environments.
• Exceptional tensile strength of 170,000 psi ensures reliable performance under high-stress conditions.
• Precise Class 3A thread fit guarantees secure, vibration-resistant fastening in critical assemblies.
• Rockwell C37 hardness provides excellent wear resistance and long-term durability.
• Partially threaded design allows for optimal grip and alignment in varied material thicknesses.
• Standard hex socket drive (3/32") enables easy installation with common tools, reducing assembly time.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety.

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these black-oxide alloy steel socket head cap screws address common challenges like vibration loosening and material fatigue. The 4-40 UNC coarse thread design provides rapid assembly and strong holding power in metals and plastics, while the partially threaded shank minimizes stress concentration. Ideal for machinery, automotive, and precision equipment, the hex drive ensures torque accuracy without stripping, enhancing operational reliability and reducing maintenance cycles in high-load environments.

Specification Summary & Compliance

This screw features a Class 3A thread fit per UNC standards, ensuring tight tolerances for secure fastening. Manufactured to ASTM A574 specifications, it includes a 1-1/8" length with a minimum thread length of 1". Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), it meets environmental and safety regulations for global industrial use.