S-91257A415 1/4"-20 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 industrial applications
• Superior corrosion protection through zinc yellow-chromate plating that extends service life in harsh environments
• Optimized thread engagement with UNC coarse threading and Class 2A fit ensuring secure fastening and vibration resistance
• Enhanced durability from Rockwell C33 hardness providing excellent wear resistance and thread integrity
• Versatile partial threading allowing for both clamping force and clearance in assembly applications
• Standard-compliant design meeting ASME B18.2.1 and SAE J429 specifications for guaranteed interoperability
• Efficient installation with external hex drive design enabling high torque application and quick assembly

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these Grade 8 hex head screws deliver exceptional performance in construction, heavy machinery, and structural assemblies where high tensile strength is critical. The zinc yellow-chromate plated finish provides superior corrosion resistance, making them ideal for outdoor equipment and marine environments. The UNC coarse threading ensures reliable fastening in materials where fine threads might strip or fail, while the partially threaded design allows for both secure clamping and proper alignment. With 150,000 psi tensile strength and Rockwell C33 hardness, these screws withstand extreme vibration and shock loads, preventing joint failure in critical applications. The external hex drive facilitates high-torque installation, reducing assembly time while maintaining Grade 8 performance standards.

Specification Summary & Compliance

This 1/4"-20 x 8" hex head screw features Class 2A thread fit per inch system standards, ensuring precise dimensional accuracy and compatibility. Manufactured to meet ASME B18.2.1 and SAE J429 specifications, the fastener guarantees consistent quality and performance. The UNC coarse thread profile with right-hand direction provides reliable engagement, while the zinc yellow-chromate plating offers environmental protection. The product complies with industry standards for Grade 8 fasteners, delivering verified 150,000 psi tensile strength and Rockwell C33 hardness for professional applications requiring certified mechanical properties.