S-91858A842 4-40 x 5/16" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 316 stainless steel construction, ideal for harsh environments and chemical exposure
• Exceptional mechanical strength with 70,000 psi tensile strength and Rockwell B80 hardness for reliable, long-lasting fastening
• Precision thread fit with Class 2A UNC coarse threads ensuring easy installation and secure engagement
• Enhanced surface durability through passivated finish, providing increased resistance to corrosion and wear
• Optimized flush mounting with standard 82° countersink angle and flat head design for seamless, low-profile applications
• Full regulatory compliance meeting ASME B18.6.3, RoHS 3, and REACH standards for global industrial use
• Complete thread coverage with fully threaded design maximizing grip strength and load distribution

Professional Applications & Engineering Value

This 4-40 UNC flat head slotted screw delivers critical engineering advantages for demanding industrial applications. Manufactured from 316 stainless steel, it provides exceptional resistance to corrosion, pitting, and chemical degradation—making it ideal for marine, chemical processing, and food equipment applications where environmental factors compromise fastener integrity. The passivated finish further enhances surface protection while maintaining electrical conductivity. With coarse UNC threading and Class 2A tolerance, installation becomes more efficient with reduced cross-threading risk, particularly in assembly line environments. The flat head design with standard 82° countersink ensures flush mounting in precision machinery, electronic enclosures, and structural components where protrusion isn't acceptable. These engineered characteristics solve common industrial pain points including fastener failure in corrosive environments, assembly time inefficiencies, and regulatory compliance challenges.

Specification Summary & Compliance

This fastener maintains Class 2A thread fit per UNC standards with precise dimensional control including 0.212" head diameter and 5/16" length. Manufacturing follows ASME B18.6.3 specifications for dimensional consistency and performance reliability. The product is fully compliant with RoHS 3 (2015/863/EU) restrictions on hazardous substances and REACH (EC 1907/2006) regulations for chemical safety, ensuring suitability for global industrial supply chains and environmentally conscious manufacturing operations.