S-91771A555 1/4"-28 x 3/8" 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
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness for reliable load-bearing performance
• Precise thread engagement with Class 2A fit and UNF fine threads ensuring vibration-resistant, secure fastening
• Optimized flush installation featuring an 82° countersink angle and undercut head profile for seamless surface finishing
• Efficient installation and removal with Phillips No. 3 drive design for consistent torque application
• Full-threaded reliability providing maximum grip length and uniform stress distribution along the entire 3/8" length
• Regulatory compliance assurance meeting ASME B18.6.3 standards and environmental regulations including RoHS 3 and REACH

Professional Applications & Engineering Value

This 1/4"-28 UNF flat head screw delivers exceptional engineering value in demanding applications where corrosion resistance and mechanical reliability are paramount. The passivated 18-8 stainless steel construction provides superior protection against oxidation and chemical exposure, making it ideal for marine, chemical processing, and outdoor equipment applications. The fine thread UNF configuration with Class 2A thread fit ensures precise engagement in tapped holes, reducing the risk of vibration-induced loosening in machinery and assembly operations. The undercut flat head profile with 82° countersink angle allows for flush mounting in precision assemblies, eliminating protrusions that could interfere with moving components. These industrial screws are engineered to maintain integrity under sustained loads while meeting critical industry specifications for dimensional accuracy and performance consistency.

Specification Summary & Compliance

This fastener maintains Class 2A thread fit tolerance per UNF standards with precise 1/4"-28 fine threading and right-hand thread direction. Manufacturing complies with ASME B18.6.3 specifications for dimensional consistency and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental responsibility and material safety in industrial applications.