S-91858A846 4-40 x 1/2" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 316 stainless steel construction and passivated finish, ideal for harsh industrial environments
• Exceptional mechanical strength with 70,000 psi tensile strength and Rockwell B80 hardness for reliable load-bearing performance
• Precision thread engagement through UNC coarse spacing and Class 2A fit ensures secure fastening and vibration resistance
• Optimized flush mounting with standard 82° countersink angle and flat head design for seamless surface integration
• Full-threaded design provides maximum grip length and uniform stress distribution across the entire 1/2" length
• Slotted drive compatibility allows for quick installation with standard tools while maintaining traditional fastening methods
• Regulatory compliance assurance meeting ASME B18.6.3 specifications and environmental standards including RoHS 3 and REACH

Professional Applications & Engineering Value

This 4-40 UNC flat head slotted screw in 316 stainless steel delivers critical performance in demanding applications where corrosion resistance and mechanical integrity are paramount. The combination of passivated finish and premium material composition provides exceptional protection against chemical exposure, saltwater environments, and industrial contaminants. The fully threaded design with coarse spacing ensures rapid installation and superior holding power in materials ranging from metals to composites. Engineering teams specify these flat head screws for precision equipment, marine hardware, chemical processing systems, and food processing machinery where reliable fastening and regulatory compliance are non-negotiable. The 82° countersink angle facilitates perfect flush mounting in standardized recesses, eliminating protrusions that could interfere with moving components or compromise aesthetic requirements.

Specification Summary & Compliance

Manufactured to exacting Class 2A thread fit tolerances with UNC (Unified National Coarse) thread form ensuring interchangeability and consistent performance. The screw conforms to ASME B18.6.3 dimensional standards for flat head machine screws. Environmental compliance includes RoHS 3 (2015/863/EU) restriction of hazardous substances and REACH (EC 1907/2006) regulations for chemical safety. Mechanical properties include 70,000 psi tensile strength and Rockwell B80 hardness for durable performance in industrial fastening applications.