S-91771A122 4-40 x 1 3/4" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with passivated 18-8 stainless steel construction, ideal for harsh industrial environments
• High tensile strength of 80,000 psi ensures reliable fastening under demanding mechanical loads
• Precision Class 2A thread fit guarantees smooth installation and consistent engagement in mating components
• Fully threaded design provides maximum grip length and uniform load distribution across the entire fastener
• Standard 82° countersink angle enables flush mounting for clean, professional finishes in assembled products
• Phillips No. 1 drive compatibility offers familiar, efficient installation with common industrial tools
• Comprehensive compliance with ASME B18.6.3, RoHS 3 and REACH ensures regulatory acceptance for global applications

Professional Applications & Engineering Value

These 4-40 UNC flat head Phillips machine screws deliver exceptional engineering value in precision assembly applications where corrosion resistance and mechanical reliability are critical. The passivated 18-8 stainless steel construction provides superior protection against oxidation and chemical exposure, making these fasteners ideal for electronics enclosures, machinery components, and marine equipment. The combination of fully threaded design and Class 2A thread fit ensures maximum thread engagement and consistent clamping force, while the standard 82° countersink angle creates seamless flush mounting in countersunk holes. With 80,000 psi tensile strength and Rockwell B80 hardness, these screws maintain structural integrity in high-vibration environments, preventing loosening and failure in demanding industrial applications.

Specification Summary & Compliance

This 1 3/4" flat head screw features precision 4-40 UNC coarse threads with Class 2A thread fit tolerance for consistent mating performance. Manufacturing complies with ASME B18.6.3 specifications for dimensional accuracy and quality assurance. The product meets RoHS 3 (2015/863/EU) compliance for restricted hazardous substances and REACH (EC 1907/2006) standards for chemical safety, ensuring environmental regulatory acceptance for international industrial applications.