S-91781A121 4-40 x 2" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel and passivated finish for extended service life in harsh environments
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness to withstand high-stress applications
• Precision thread engagement through Class 2A fit and UNC coarse threads ensuring reliable, vibration-resistant fastening
• Optimal flush mounting with standard 82° countersink angle and flat head design for seamless surface integration
• Full-length threading providing maximum grip and load distribution across the entire 2" length
• Industry-standard compliance meeting ASME B18.6.3 specifications for dimensional accuracy and performance reliability
• Environmental responsibility through RoHS 3 and REACH compliance, ensuring safe usage in regulated industries

Professional Applications & Engineering Value

These 4-40 UNC flat head slotted screws deliver critical engineering advantages for industrial assembly applications where reliability and corrosion resistance are paramount. The combination of 18-8 stainless steel construction and passivated finish provides exceptional protection against oxidation and chemical exposure, making them ideal for marine, food processing, and outdoor equipment applications. The fully threaded design and Class 2A thread fit ensure maximum thread engagement and vibration resistance, preventing loosening in dynamic environments. With their standard 82° countersink angle, these screws facilitate flush mounting in precision machinery, electronic enclosures, and structural assemblies where protrusion must be avoided. The coarse UNC threading enables quick installation and superior holding power in various materials, reducing assembly time while maintaining joint integrity under heavy loads.

Specification Summary & Compliance

Manufactured to precise dimensional standards with Class 2A thread fit and UNC coarse thread specifications ensuring consistent performance. These screws conform to ASME B18.6.3 standards for dimensional accuracy and mechanical properties. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations confirms environmental responsibility and material safety. The inch system measurements guarantee compatibility with North American machinery and equipment specifications.