S-91771A537 1/4"-20 x 1/2" 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, ideal for harsh industrial environments.
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness for reliable, long-term fastening.
• Precise thread engagement with Class 2A fit and coarse UNC threading, ensuring easy installation and secure hold.
• Optimized flush mounting thanks to the standard 82° countersink angle and flat head design for a smooth, professional finish.
• Efficient drive performance with No. 3 Phillips drive, reducing cam-out and speeding up assembly in high-volume applications.
• Full threading along the 1/2" length provides maximum grip and uniform stress distribution in various material thicknesses.
• Compliance with major industry standards including ASME B18.6.3, RoHS 3, and REACH, ensuring safety and regulatory acceptance.

Professional Applications & Engineering Value

These 1/4"-20 UNC flat head Phillips screws are engineered to address common industrial challenges such as vibration loosening, corrosion in moist or chemical-exposed settings, and the need for rapid, reliable assembly. The passivated 18-8 stainless steel offers excellent resistance to oxidation and wear, extending service life in machinery, electrical enclosures, and structural frameworks. The coarse thread spacing and Class 2A thread fit facilitate quick insertion into metals and plastics, minimizing installation time while maintaining high clamp load. With a standard 82° countersink angle, these screws sit flush, reducing snag risks and improving aesthetics in visible applications. Ideal for heavy-duty fastening in automotive, aerospace, and construction sectors, they deliver consistent performance under stress, backed by 80,000 psi tensile strength.

Specification Summary & Compliance

This screw features a 1/4"-20 UNC thread with Class 2A precision fit and coarse spacing, ensuring dimensional accuracy per ASME B18.6.3 standards. The fully threaded design and right-hand orientation support efficient driving. Compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), confirming adherence to environmental and safety regulations for industrial use.