S-91771A120 4-40 x 2" 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 for extended service life in harsh environments
• Exceptional mechanical strength with 80,000 PSI tensile strength and Rockwell B80 hardness for reliable load-bearing performance
• Precision thread engagement with Class 2A UNC coarse threads ensuring consistent fit and vibration resistance
• Streamlined installation featuring Phillips No. 1 drive and standard 82° countersink for flush mounting and reduced assembly time
• Full threading coverage along the 2" length provides maximum grip and holding power across the entire fastener
• Regulatory compliance meeting ASME B18.6.3 specifications and environmental standards including RoHS 3 and REACH
• Right-hand thread design with standardized UNC coarse spacing for compatibility with common industrial components

Professional Applications & Engineering Value

These 4-40 UNC flat head screws deliver critical engineering advantages where corrosion resistance and structural integrity are paramount. The passivated 18-8 stainless steel construction provides exceptional protection against oxidation and chemical degradation, making them ideal for marine equipment, food processing machinery, and outdoor industrial applications. The combination of 80,000 PSI tensile strength and fully threaded design ensures maximum clamping force distribution, preventing joint failure under vibration and dynamic loads. The standard 82° countersink angle and Phillips drive facilitate rapid installation while maintaining flush surface profiles in precision assemblies. These flat head machine screws solve common fastening challenges by offering predictable performance across temperature variations and exposure conditions.

Specification Summary & Compliance

Manufactured to exacting Class 2A thread fit tolerances with UNC coarse threading specifications. Complies with ASME B18.6.3 mechanical standards for dimensional accuracy and performance. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance requirements. Features include right-hand thread direction, 2" fully threaded length, and standard flat head profile with consistent mechanical properties verified through quality control processes.