S-91257A773 9/16"-12 x 4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 150,000 psi tensile strength and Rockwell C33 hardness for reliable performance in high-stress industrial environments.
• Superior corrosion resistance provided by the zinc yellow-chromate plating, extending service life in harsh conditions and reducing maintenance frequency.
• Optimized torque transmission through the external hex drive design, enabling secure installation with standard tools and minimizing slippage risks.
• Enhanced assembly efficiency with coarse 9/16"-12 UNC threads and Class 2A fit, ensuring quick engagement and consistent clamping force.
• Reduced material stress concentration due to partial threading, improving fatigue resistance and preventing thread damage in dynamic applications.
• Guaranteed dimensional consistency through compliance with ASME B18.2.1 and SAE J429 standards, ensuring interchangeability and reliable fit.
• Environmentally responsible manufacturing with RoHS 3 and REACH compliance, meeting global regulatory requirements for hazardous substance restrictions.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, this Grade 8 hex head screw delivers critical reliability in construction machinery, automotive assemblies, and structural frameworks. The steel construction with zinc yellow-chromate plating combats oxidation and chemical exposure, significantly reducing failure risks in outdoor or corrosive environments. Its 9/16"-12 UNC coarse thread design enables rapid installation in thick materials, while the partial threading minimizes stress risers at the shank-to-thread transition zone. The external hex drive accommodates high-torque tools without deformation, ensuring precise clamping force for vibration-resistant connections. This fastener solves common engineering challenges like joint loosening, galvanic corrosion, and assembly time inefficiencies, making it ideal for critical bolting applications requiring 150,000 psi tensile strength and long-term durability.

Specification Summary & Compliance

This 4" length hex head screw features precise Class 2A thread fit with 9/16"-12 UNC coarse threads and a minimum thread length of 1-3/8". Manufacturing adheres to ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring no restricted substances are present. The zinc yellow-chromate finish provides consistent corrosion protection while maintaining Grade 8 strength classification requirements.