S-91257A805 5/8"-11 x 2 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 150,000 PSI ensures reliable performance in the most demanding heavy-duty applications, reducing the risk of fastener failure.
• Superior corrosion resistance provided by the zinc yellow-chromate plating extends the fastener's service life, even in harsh or outdoor environments.
• High-strength Grade 8 classification and Rockwell C33 hardness offer excellent durability and resistance to wear and deformation under high stress.
• Coarse UNC thread design allows for faster installation and easier alignment, improving assembly efficiency in industrial settings.
• Class 2A thread fit ensures consistent, reliable engagement with nuts and tapped holes, minimizing cross-threading and ensuring secure connections.
• Partially threaded shank provides an unthreaded section for increased shear strength, ideal for applications requiring precise clamping force.
• External hex drive and hex head design offers high torque capability and easy installation with standard tools, speeding up maintenance and assembly processes.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to solve critical challenges in heavy machinery, construction, and automotive assembly, where high tensile strength and corrosion resistance are paramount. The zinc yellow-chromate plated steel construction combats rust and environmental degradation, ensuring long-term reliability in demanding conditions. Its 5/8"-11 UNC coarse thread and partial threading enhance grip and distribute stress effectively, reducing the risk of loosening under vibration or dynamic loads. By meeting rigorous standards like ASME B18.2.1 and SAE J429, it delivers consistent performance for structural fastening, equipment frames, and other high-strength industrial applications, minimizing downtime and maintenance costs.

Specification Summary & Compliance

This fastener features precise Class 2A thread fit and UNC coarse threading with a size of 5/8"-11, ensuring compatibility and ease of use. It complies with ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and performance. Additionally, it is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, adhering to environmental and safety regulations for hazardous substances.