S-91781A559 1/4"-28 x 3/4" 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 offering 80,000 psi tensile strength and Rockwell B80 hardness for reliable, long-lasting fastening.
• Precise thread engagement with Class 2A fit and UNF fine threads, ensuring secure connections and reducing the risk of stripping.
• Flush mounting capability due to the standard flat head and 82° countersink angle, providing a smooth, unobtrusive surface finish.
• Broad industrial compliance meeting ASME B18.6.3 standards and being RoHS 3 & REACH compliant for safe, regulated use.
• Easy installation and removal with a slotted drive, compatible with standard tools for efficient maintenance.
• Full threading along the 3/4" length maximizes grip and load distribution in assemblies.

Professional Applications & Engineering Value

This 1/4"-28 UNF flat head slotted screw is engineered to address critical challenges in precision assemblies where flush surface mounting and corrosion resistance are paramount. The 18-8 stainless steel material, enhanced by a passivated finish, provides excellent protection against oxidation and chemical exposure, making it suitable for industrial machinery, electronic enclosures, and marine applications. Its fine thread (UNF) design and Class 2A thread fit ensure tight, vibration-resistant connections, reducing the need for frequent retightening. The fully threaded shank and 82° countersink angle allow for seamless integration into tapered holes, offering a secure hold without protrusion. By meeting ASME B18.6.3 specifications, this screw delivers consistent performance, minimizing downtime and maintenance costs in demanding settings.

Specification Summary & Compliance

This screw adheres to Class 2A thread fit tolerances and UNF (Unified National Fine) thread standards, ensuring dimensional accuracy and interchangeability. It is manufactured in compliance with ASME B18.6.3 for mechanical fasteners and is RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, confirming its suitability for environmentally regulated and industrial applications.