S-91257A569 1/4"-28 x 2 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 150,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior corrosion resistance from Zinc Yellow-Chromate plating extends service life in harsh industrial environments, minimizing maintenance needs.
• High hardness rating (Rockwell C33) provides excellent wear resistance, maintaining structural integrity under repeated loads.
• Precise Class 2A thread fit with UNF fine threading offers secure, vibration-resistant connections for critical assemblies.
• Partially threaded design allows for controlled clamping force, ideal for applications requiring specific grip ranges.
• External hex drive enables easy installation and removal with standard tools, improving assembly efficiency.
• Compliance with major standards including ASME B18.2.1 and SAE J429 ensures consistent quality and interoperability in professional settings.

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering value in demanding environments where failure is not an option. The steel construction combined with Zinc Yellow-Chromate plating provides robust protection against corrosion, making it suitable for outdoor equipment, automotive assemblies, and heavy machinery exposed to moisture and chemicals. The 1/4"-28 UNF fine thread configuration ensures superior vibration resistance compared to coarse threads, maintaining clamp load integrity in dynamic applications. With partial threading, engineers can precisely control the engaged length, preventing thread stripping in soft materials while providing maximum strength in the shank. These industrial fasteners solve common pain points like premature corrosion, loosening under vibration, and insufficient clamping force, offering a reliable solution for critical connections in construction, manufacturing, and transportation sectors.

Specification Summary & Compliance

This fastener maintains precise Class 2A thread fit per UNF standards with 1/4"-28 thread size and fine thread spacing. Manufacturing complies with ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global markets.