S-91253A109 4-40 x 7/16" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating on alloy steel, extending service life in demanding environments
• Exceptional tensile strength of 130,000 psi ensures reliable fastening under high-stress industrial applications
• Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant assemblies
• Fully threaded design with 82° countersink enables flush mounting and uniform load distribution
• Hex drive compatibility allows high-torque installation with standard industrial tools
• Compliance with ASTM F835, RoHS 3, and REACH guarantees material safety and regulatory adherence
• Rockwell C39 hardness rating maintains thread integrity through repeated use

Professional Applications & Engineering Value

These 4-40 UNC flat head screws with black-oxide alloy steel construction address critical industrial fastening challenges. The Class 3A thread fit and coarse thread spacing prevent loosening in high-vibration machinery, while the 82° countersink angle creates seamless surface transitions in precision assemblies. Engineered for industrial applications requiring high tensile strength, these fully threaded fasteners distribute mechanical loads evenly across joined components. The hex drive design ensures efficient installation in confined spaces, making them ideal for automotive, aerospace, and heavy equipment manufacturing where reliability and regulatory compliance are paramount.

Specification Summary & Compliance

Manufactured to ASTM F835 specifications with Class 3A thread fit (equivalent to ISO 6g tolerance for unified threads). The 4-40 UNC coarse thread maintains consistent engagement while the right-hand thread direction follows industry standards. Full compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations ensures environmental safety and material traceability.