S-91257A572 1/4"-28 x 2 1/4" 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 applications
• Superior corrosion resistance through zinc yellow-chromate plating that extends service life in demanding environments
• Precise thread engagement with Class 2A UNF fine threads ensuring secure fastening and vibration resistance
• Optimized torque transmission via external hex drive design that prevents tool slippage during installation
• Versatile partial threading allowing for both clamping and alignment functions in assembly operations
• Heavy-duty construction meeting Grade 8 specifications for the most demanding industrial applications
• Regulatory compliance assurance with ASME B18.2.1, SAE J429, RoHS 3, and REACH standards for global acceptance

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver critical engineering solutions where failure is not an option. The 150,000 psi tensile strength and Rockwell C33 hardness provide exceptional resistance to shear and tensile forces in heavy machinery, construction equipment, and automotive assemblies. The zinc yellow-chromate plating creates a protective barrier against corrosion in outdoor or chemically aggressive environments, significantly extending maintenance intervals. The 1/4"-28 UNF fine thread configuration offers superior vibration resistance compared to coarse threads, making these partially threaded screws ideal for applications requiring precise clamping force distribution. The external hex drive design ensures maximum torque application without cam-out, while the 2 1/4" length provides sufficient engagement for structural connections in industrial frameworks and equipment manufacturing.

Specification Summary & Compliance

This Grade 8 hex head screw features precise Class 2A thread fit tolerances with 1/4"-28 UNF fine threads in right-hand direction and 3/4" minimum thread length. Manufactured to ASME B18.2.1 and SAE J429 specifications, these industrial fasteners maintain dimensional accuracy and performance consistency. The product is fully compliant with RoHS 3 (2015/863/EU) restrictions on hazardous substances and REACH (EC 1907/2006) regulations concerning chemical safety, ensuring environmental responsibility and workplace safety standards are met for global industrial applications.