S-91253A171 6-40 x 5/8" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with Black-Oxide finish, extending service life in harsh industrial environments
• Exceptional tensile strength of 130,000 psi ensures reliable performance under heavy loads and vibration
• Precision Class 3A thread fit guarantees secure fastening with minimal play in critical assemblies
• Full threading design provides maximum grip length and uniform stress distribution
• 82° countersink angle enables flush mounting for streamlined surfaces and improved aesthetics
• Hex drive compatibility allows for high-torque installation with standard industrial tools
• Rockwell C39 hardness maintains thread integrity and prevents stripping during repeated use

Professional Applications & Engineering Value

These 6-40 UNF flat head screws with Class 3A precision threads deliver exceptional performance in demanding applications where vibration resistance and reliable fastening are critical. The Black-Oxide Alloy Steel construction provides superior protection against corrosion while maintaining the 130,000 psi tensile strength required for heavy-duty assemblies. The fine UNF threading ensures secure fastening in thin materials and high-vibration environments, while the 82° countersink creates flush surfaces ideal for aerospace components, precision machinery, and electronic enclosures. The hex drive design enables efficient installation in confined spaces, making these fully threaded screws essential for maintenance-critical industrial applications.

Specification Summary & Compliance

Manufactured to Class 3A thread fit tolerances with UNF fine threading (6-40) in inch system measurements. Complies with ASTM F835 specifications for mechanical properties and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards. Features right-hand thread direction with 5/8" length and fully threaded design for consistent performance across industrial applications.