S-91781A113 4-40 x 3/4" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance thanks to 18-8 stainless steel construction and passivated finish, ensuring longevity in harsh environments
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness for reliable performance under high-stress conditions
• Precision thread fit with Class 2A UNC coarse threads providing secure fastening and vibration resistance in industrial assemblies
• Optimal flush mounting with standard 82° countersink angle and flat head design for seamless integration into surfaces
• Full threading capability ensuring maximum grip length and uniform load distribution across the entire fastener
• Regulatory compliance meeting ASME B18.6.3 specifications and environmental standards including RoHS 3 and REACH
• Wide industrial compatibility with right-hand thread direction and slotted drive for versatile installation across various applications

Professional Applications & Engineering Value

These 4-40 UNC flat head slotted screws deliver critical engineering value by addressing common industrial fastening challenges. The 18-8 stainless steel material combined with passivated finish provides exceptional resistance to corrosion, oxidation, and chemical exposure, making them ideal for demanding environments like marine equipment, food processing machinery, and outdoor installations. The fully threaded design with coarse UNC threads ensures maximum engagement strength while preventing loosening from vibration - a common failure point in industrial machinery. The 82° countersink angle and flat head profile allow for flush mounting in precision assemblies where surface protrusion isn't acceptable. These screws solve critical issues of material degradation, thread stripping, and installation efficiency across manufacturing, electronics, and mechanical engineering applications where ASME B18.6.3 compliance and consistent performance are mandatory.

Specification Summary & Compliance

This fastener maintains Class 2A thread fit tolerance per UNC standards with precise dimensional control. Manufacturing follows ASME B18.6.3 specifications for flat head slotted screws, ensuring interchangeability and reliability. The product is fully compliant with RoHS 3 (2015/863/EU) regulations and REACH (EC 1907/2006) environmental standards, containing no restricted substances. The combination of inch system measurements, right-hand thread direction, and standardized 82° countersink angle guarantees consistent performance across industrial applications requiring precise mechanical fastening solutions.