S-91251A115 4-40 x 1" 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 demanding applications.
• 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 provides tighter tolerances for secure, vibration-resistant assemblies, enhancing joint integrity and safety.
• High hardness rating (Rockwell C37) offers excellent wear resistance, maintaining thread form and drive integrity through repeated use.
• Coarse UNC threads enable faster installation and reduced cross-threading risks, speeding up assembly processes in production lines.
• Partially threaded design allows for controlled clamping force, ideal for applications requiring precise positioning and shear resistance.
• Compact 3/32" hex drive and standard socket head profile facilitate easy access in confined spaces with standard tools, improving installation efficiency.

Professional Applications & Engineering Value

Engineered for industrial applications where reliability is critical, these socket head cap screws combine black-oxide alloy steel construction with UNC coarse threads to address common engineering challenges. The Class 3A thread fit ensures minimal backlash in precision machinery, while the 170,000 PSI tensile strength withstands dynamic loads in automotive, aerospace, and heavy equipment assemblies. The partially threaded shank design provides optimal grip in materials prone to stress concentration, reducing the likelihood of loosening under vibration. This makes them ideal for securing components in enclosures, motors, and structural frames where corrosion resistance and long-term durability are essential for minimizing downtime and maintenance costs.

Specification Summary & Compliance

This socket head cap screw adheres to ASTM A574 manufacturing standards, with precise 4-40 UNC coarse threads meeting Class 3A dimensional tolerances for consistent fit. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material traceability. The specified thread diameter of 0.112" and minimum thread length of 3/4" guarantee reliable engagement, backed by the Rockwell C37 hardness for sustained performance in industrial settings.