S-93791A557 1/4"-20 x 3/4" ASME B18.3 Stainless Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and black-oxide passivated finish, ideal for harsh industrial environments.
• Exceptional mechanical strength offering 70,000 psi tensile strength and Rockwell B55 hardness for reliable, heavy-duty fastening.
• Precise, secure thread engagement with UNC coarse threading and Class 3A fit, reducing cross-threading and ensuring consistent performance.
• Efficient installation and flush seating thanks to the standard 82° countersink angle and hex drive design for easy torque application.
• Full thread coverage along the 3/4" length provides maximum grip and load distribution in assembled components.
• Compliance with major industry standards including ASME B18.3, RoHS 3, and REACH, ensuring safety and regulatory adherence.
• Durable, long-lasting performance in demanding applications due to high-quality material and precise manufacturing.

Professional Applications & Engineering Value

These 1/4"-20 flat head hex screws are engineered to address critical fastening challenges in industrial settings. The 18-8 stainless steel material, combined with a black-oxide passivated finish, provides excellent resistance to corrosion and wear, making them suitable for machinery, automotive, and outdoor equipment where exposure to moisture and chemicals is common. The UNC coarse threading and Class 3A thread fit ensure quick, reliable assembly with minimal risk of stripping, while the hex drive and 82° countersink angle allow for flush mounting and easy access in tight spaces. Fully threaded and offering 70,000 psi tensile strength, these screws deliver consistent clamping force and vibration resistance, reducing maintenance needs and enhancing the longevity of assembled structures in heavy-duty applications.

Specification Summary & Compliance

This product adheres to precise dimensional and performance standards, including Class 3A thread fit for tight tolerances and UNC coarse thread specifications. It meets ASME B18.3 manufacturing standards, ensuring reliability in mechanical assemblies. Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting environmental safety and restricted substance management in industrial supply chains.