S-91771A117 4-40 x 1 1/4" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with passivated 18-8 stainless steel construction for long-lasting performance in harsh environments
• Superior mechanical strength with 80,000 PSI tensile strength and Rockwell B80 hardness for reliable load-bearing applications
• Optimized installation efficiency featuring Phillips No. 1 drive and standard flat head profile for quick, secure fastening
• Precision thread engagement with Class 2A UNC coarse threads ensuring consistent fit and vibration resistance
• Flush mounting capability with 82° countersink angle for seamless surface integration in machined components
• Full-threaded design providing maximum grip length and uniform stress distribution across the entire fastener
• Regulatory compliance assurance meeting ASME B18.6.3 specifications and international environmental standards

Professional Applications & Engineering Value

These 4-40 UNC flat head screws deliver critical engineering solutions where corrosion resistance and structural integrity are paramount. The passivated 18-8 stainless steel construction prevents galvanic corrosion and chemical degradation in industrial environments, while the 80,000 PSI tensile strength ensures reliable performance under mechanical stress. The combination of Phillips No. 1 drive and 82° countersink angle enables flush mounting in precision machinery, electronic enclosures, and automotive assemblies. The fully threaded coarse pitch design provides superior holding power in softer materials and rapid installation in high-volume manufacturing operations, making these machine screws ideal for applications requiring both aesthetic cleanliness and mechanical reliability.

Specification Summary & Compliance

Manufactured to exacting ASME B18.6.3 specifications with Class 2A thread fit tolerance for consistent mating with corresponding nuts and threaded holes. The 1-1/4" length and 4-40 UNC coarse threads maintain dimensional accuracy across production batches. Compliant with RoHS 3 (2015/863/EU) restrictions on hazardous substances and REACH (EC 1907/2006) regulations for chemical safety, ensuring global environmental standard adherence for industrial fastener applications.