S-91257A430 1/4"-28 x 8" 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 for reliable performance in high-stress applications
• Superior corrosion resistance through zinc yellow-chromate plating, extending service life in harsh industrial environments
• Precise thread engagement with Class 2A UNF fine threads ensuring secure fastening and vibration resistance
• Enhanced durability from Rockwell C33 hardness steel construction, maintaining integrity under repeated stress
• Optimized torque transmission via external hex drive design for efficient installation with standard tools
• Versatile partial threading allowing both secure clamping and adjustment flexibility in assembly applications
• Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for guaranteed interoperability

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions for heavy-duty industrial applications where fastener failure is not an option. The combination of 150,000 PSI tensile strength and Rockwell C33 hardness provides exceptional resistance to shear and tensile forces in machinery, structural assemblies, and equipment manufacturing. The zinc yellow-chromate plating creates a protective barrier against corrosion in demanding environments, while the 1/4"-28 UNF fine threads with Class 2A fit ensure precise engagement and vibration resistance. The partial threading design allows for both secure clamping in the threaded portion and clearance in the shank area, making these industrial fasteners ideal for applications requiring both strength and adjustability in construction, automotive, and manufacturing sectors.

Specification Summary & Compliance

Manufactured to exacting ASME B18.2.1 and SAE J429 standards, this Grade 8 hex head screw features precision Class 2A thread fit with 1/4"-28 UNF fine thread configuration. The fastener maintains dimensional accuracy throughout its 8-inch length with partial threading beginning at 1" minimum thread length. The external hex drive with 7/16" head width ensures compatibility with standard industrial tools. Compliance with industry specifications guarantees consistent performance and interchangeability in professional applications requiring reliable heavy-duty fastening solutions.