S-91255A023 4-40 x 1 1/2" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional durability with 120,000 psi tensile strength and Rockwell C39 hardness for reliable performance in demanding industrial environments
• Superior corrosion resistance through black-oxide coating on alloy steel, extending service life in various operating conditions
• Precise thread engagement with Class 3A fit and UNC coarse threading ensuring secure fastening and vibration resistance
• Efficient installation via 1/16" hex drive design providing positive torque transmission and reduced tool slippage
• Full threading capability offering consistent holding power along the entire 1½" length for versatile application requirements
• Rounded button head profile creating a low-profile finish that minimizes snagging while maintaining structural integrity
• Regulatory compliance assurance meeting international standards for safety and environmental requirements

Professional Applications & Engineering Value

These 4-40 UNC coarse thread rounded head screws deliver critical engineering solutions where high tensile strength and corrosion resistance are paramount. The black-oxide alloy steel construction provides superior protection against environmental degradation, while the Class 3A thread fit ensures precise engagement in critical assemblies. The combination of fully threaded design and hex drive configuration addresses common installation challenges in industrial equipment, electronic enclosures, and machinery components. The rounded button head profile offers both aesthetic appeal and functional benefits by reducing protrusion risks in confined spaces. These screws are engineered to maintain integrity under sustained loads, making them ideal for applications requiring reliable fastening performance in manufacturing, automation, and heavy equipment sectors.

Specification Summary & Compliance

Manufactured to exacting inch system dimensions with Class 3A thread fit tolerance per UNC standards, ensuring precise mechanical compatibility. These fully threaded screws comply with ASME B18.3 and ASTM F835 manufacturing specifications for consistent quality and performance. Environmental compliance is verified through RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) certifications, confirming adherence to international substance restriction guidelines. The right-hand thread direction and coarse thread spacing provide standardized installation characteristics across industrial applications.