S-91257A728 1/2"-13 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 environments
• Superior corrosion resistance through zinc yellow-chromate plating that protects against rust and extends service life in harsh conditions
• Optimized torque transmission with external hex drive design providing secure tool engagement and efficient installation
• Enhanced vibration resistance through Class 2A thread fit and coarse UNC threading that maintains secure fastening under dynamic loads
• Strategic thread placement with partial threading that concentrates strength where needed while reducing overall weight
• Industry-standard compatibility meeting ASME B18.2.1 and SAE J429 specifications for reliable interchangeability
• Environmental compliance assurance with RoHS 3 and REACH compliance for safe use in regulated 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 zinc yellow-chromate plated steel construction provides exceptional corrosion resistance in demanding environments including manufacturing equipment, structural frameworks, and machinery assembly. The 1/2"-13 UNC coarse threading with Class 2A fit ensures reliable engagement in both metallic and high-density materials, while the partial threading design concentrates strength at the critical shear plane. With 150,000 psi tensile strength and Rockwell C33 hardness, these fasteners withstand extreme vibration, shock loads, and temperature variations common in construction, automotive, and heavy equipment applications, providing engineers with a trusted solution for critical connections.

Specification Summary & Compliance

This 4" hex head screw features precise Class 2A thread fit with 1/2"-13 UNC coarse threading and 1 1/4" minimum thread length. Manufactured to ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring dimensional accuracy and mechanical properties. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards, making them suitable for use in regulated industries and international markets.