S-91257A566 1/4"-28 x 1 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 industrial applications
• Superior corrosion resistance with zinc yellow-chromate plating for extended service life in harsh environments
• Precision UNF fine threading (Class 2A fit) provides secure fastening with minimal vibration loosening
• Grade 8 strength certification guarantees consistent quality and durability for critical assemblies
• External hex drive design enables easy installation and removal with standard tools
• Partial threading configuration allows for optimal grip and clamping force distribution
• Rockwell C33 hardness rating maintains structural integrity under heavy loads and impact

Professional Applications & Engineering Value

These Grade 8 hex head screws with UNF fine thread configuration are engineered to address critical fastening challenges in heavy machinery, construction equipment, and automotive assemblies. The zinc yellow-chromate plating provides superior protection against corrosion in demanding industrial environments, while the 1/4"-28 thread size with Class 2A fit ensures precise engagement and vibration resistance. The partially threaded design concentrates clamping force where needed most, preventing joint failure in high-vibration applications. With 150,000 PSI tensile strength and Rockwell C33 hardness, these steel fasteners maintain integrity under extreme mechanical stress, making them ideal for structural connections, engine components, and load-bearing assemblies requiring reliable, long-term performance.

Specification Summary & Compliance

This 1/4"-28 hex head screw features precise Class 2A thread fit with UNF fine threading standards and 1-1/2" length with minimum 3/4" thread engagement. Manufactured to ASME B18.2.1 specifications and SAE J429 Grade 8 requirements, ensuring dimensional accuracy and mechanical performance. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, providing assurance for global industrial applications requiring certified material safety and environmental responsibility.