S-91257A827 5/8"-18 x 3" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional durability with Grade 8 steel construction, providing reliable performance in high-stress environments.
• Superior corrosion resistance from zinc yellow-chromate plating, extending service life in harsh industrial conditions.
• High tensile strength of 150,000 PSI ensures secure fastening for heavy machinery and structural applications.
• Precise Class 2A thread fit guarantees easy assembly and consistent engagement without cross-threading risks.
• Partially threaded UNF design allows for focused clamping force and reduced weight in critical joints.
• External hex drive compatibility enables quick installation using standard tools, saving time on the job site.
• Compliance with ASME, SAE, RoHS, and REACH standards ensures safety, quality, and environmental responsibility.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address demanding industrial challenges, such as vibration resistance and long-term structural integrity. The 5/8"-18 UNF fine thread and partially threaded configuration provide optimal load distribution, minimizing stress concentration in heavy-duty assemblies like construction equipment, automotive frames, and machinery bases. Made from high-strength steel with a zinc yellow-chromate finish, it combats rust and wear in corrosive environments, reducing maintenance costs. Its 150,000 PSI tensile strength and Rockwell C33 hardness ensure reliable performance under extreme pressures, making it ideal for applications where failure is not an option.

Specification Summary & Compliance

This fastener adheres to Class 2A thread fit tolerances for precise alignment and meets ASME B18.2.1 and SAE J429 specifications. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material reliability.