S-91257A103 1/4"-20 x 4 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 capability with 150,000 PSI tensile strength for reliable performance in high-stress applications
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh environments
• Optimized installation efficiency through UNC coarse threading that resists cross-threading and enables faster assembly
• Enhanced torque transmission via the external hex drive design, allowing for secure tightening with standard tools
• Precision thread engagement ensured by Class 2A thread fit, delivering consistent clamping force and vibration resistance
• Reduced weight without compromising strength through the partially threaded design, ideal for applications requiring precise fastener placement
• Industry-standard compliance with ASME B18.2.1 and SAE J429 specifications, guaranteeing interchangeability and quality assurance

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions for industrial applications where failure is not an option. The steel construction with Rockwell C33 hardness provides exceptional durability against shear and tensile forces, while the zinc yellow-chromate plating creates a protective barrier against corrosion in outdoor or chemically aggressive environments. The 1/4"-20 UNC coarse thread configuration ensures rapid installation and superior resistance to vibration loosening in heavy machinery, construction equipment, and structural assemblies. With partial threading and 4-1/4" length, this fastener offers precise load distribution while minimizing material usage. These industrial screws are engineered to maintain integrity under extreme conditions, reducing maintenance frequency and downtime in critical operations.

Specification Summary & Compliance

This heavy-duty hex head screw features precise inch measurements including 1/4"-20 UNC coarse threads with Class 2A thread fit tolerance for consistent performance. The fastener meets ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. Manufacturing complies with industry standards for Grade 8 strength classification, ensuring 150,000 PSI tensile strength and Rockwell C33 hardness. The zinc yellow-chromate plating provides corrosion protection while maintaining RoHS and REACH compliance for environmental safety.