S-91253A558 1/4"-20 x 2 3/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional durability with 130,000 psi tensile strength and Rockwell C39 hardness for reliable performance in demanding industrial environments
• Superior corrosion resistance through black-oxide coating that protects against rust and extends service life
• Precise thread engagement with Class 3A fit ensuring secure fastening and vibration resistance in critical applications
• Optimized flush mounting featuring 82° countersink angle and flat head design for smooth surface finishes
• Enhanced installation efficiency with 5/32" hex drive allowing quick, secure tool engagement and reduced assembly time
• Reliable coarse threading (UNC 1/4"-20) providing excellent holding power in various materials including metals and plastics
• Versatile partial threading design offering both gripping strength and clearance where needed

Professional Applications & Engineering Value

This black-oxide alloy steel flat head screw delivers exceptional engineering value across multiple industrial sectors. The high-strength alloy steel construction combined with black-oxide surface treatment provides superior corrosion resistance, making it ideal for machinery, automotive components, and outdoor equipment where environmental exposure is a concern. The 1/4"-20 UNC coarse thread with Class 3A fit ensures reliable fastening in metal assemblies, while the 82° countersink angle allows for flush mounting in precision applications. The partial threading design provides optimal clamping force while preventing thread damage during installation. These flat head hex drive screws are engineered to withstand high vibration environments and maintain integrity under substantial mechanical stress, solving common fastening failures in heavy-duty applications.

Specification Summary & Compliance

This flat head screw features precise dimensional accuracy with Class 3A thread fit and UNC coarse thread spacing standards. Manufacturing complies with ASTM F835 specifications for mechanical properties and performance requirements. The product meets RoHS 3 (2015/863/EU) compliance for restricted hazardous substances and REACH (EC 1907/2006) compliance for chemical safety. Thread specifications include 1/4"-20 UNC right-hand threading with minimum thread length of 1" and overall length of 2 3/4". The black-oxide alloy steel construction ensures consistent performance across industrial applications while maintaining regulatory compliance.