S-91257A204 3/4"-10 x 8 1/2" 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 under extreme loads, reducing the risk of fastener failure in critical applications.
• Superior corrosion resistance with Zinc Yellow-Chromate plating extends service life in harsh industrial environments, minimizing maintenance and replacement costs.
• High hardness rating (Rockwell C33) provides excellent wear resistance and durability, maintaining thread integrity through repeated use.
• Coarse UNC threading with Class 2A fit enables quick installation and secure fastening, even in applications with vibration or dynamic stresses.
• Partially threaded design allows for precise clamping force distribution, ideal for assemblies requiring both shear and tensile strength.
• External hex drive with 1 1/8" head width offers superior torque transmission and easy installation with standard tools.
• Full compliance with ASME B18.2.1 and SAE J429 standards guarantees consistent quality and interchangeability across industrial applications.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these Grade 8 hex head screws deliver critical performance where failure is not an option. The combination of 150,000 psi tensile strength and Rockwell C33 hardness makes them ideal for structural connections, machinery assembly, and equipment manufacturing that demand maximum load-bearing capacity. The zinc yellow-chromate plating provides essential corrosion protection in outdoor or chemically aggressive environments, while the coarse UNC thread maintains secure fastening even under vibration. With partial threading and Class 2A thread fit, these bolts offer precise clamping control for critical joints in construction, automotive, and heavy equipment sectors where reliability and safety are paramount.

Specification Summary & Compliance

This 3/4"-10 UNC hex head screw features Class 2A thread fit with coarse thread spacing and minimum 2" thread length. Manufactured to ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring dimensional accuracy and mechanical properties. The fastener is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting current environmental regulations for industrial use.