S-91781A124 5-40 x 1/4" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish, ideal for harsh industrial environments
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness for reliable, long-term fastening performance
• Precision thread engagement through Class 2A thread fit and UNC coarse threading, ensuring easy installation and secure connections
• Optimized flush mounting with standard 82° countersink angle and flat head design, providing a smooth surface finish
• Broad compliance coverage meeting ASME B18.6.3 specifications plus RoHS 3 and REACH environmental regulations
• Versatile drive compatibility with slotted drive style for simple installation using standard tools
• Full-threaded design maximizing grip strength and load distribution across the entire fastener length

Professional Applications & Engineering Value

These 5-40 UNC flat head slotted screws deliver critical performance advantages in demanding applications where corrosion resistance and mechanical reliability are paramount. The combination of 18-8 stainless steel material with passivated finish creates a robust barrier against chemical exposure and environmental degradation, significantly extending service life in industrial settings. The fully threaded design with coarse thread spacing ensures maximum holding power in various substrates while the 82° countersink angle provides seamless integration into precision assemblies. These fasteners solve common engineering challenges by maintaining 80,000 psi tensile strength under load while offering consistent performance in machinery, equipment manufacturing, and structural applications where vibration resistance and long-term fastening integrity are essential.

Specification Summary & Compliance

Manufactured to exacting ASME B18.6.3 standards, these screws feature precision Class 2A thread fit with UNC coarse thread spacing and right-hand threading. The dimensional specifications include 0.125" thread diameter, 1/4" length, and standard flat head profile with 0.237" head diameter. Full compliance is maintained with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring these components meet the latest international standards for restricted substances and chemical safety.