S-91257A490 1/2"-20 x 6 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 and durability under heavy loads and vibration.
• Fine UNF threading with Class 2A fit offers precise engagement and vibration resistance, ideal for machinery requiring secure fastening.
• Partially threaded design allows for controlled clamping force and easier alignment in assembled components.
• External hex drive and hex head facilitate straightforward installation and removal with standard tools, saving time during maintenance.
• Compliance with major standards including ASME B18.2.1 and SAE J429 ensures consistent quality and interoperability in industrial systems.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy-duty applications, such as construction equipment, automotive assemblies, and industrial machinery. The steel material combined with Rockwell C33 hardness resists deformation under extreme loads, while the zinc yellow-chromate plating provides a robust barrier against corrosion, reducing downtime in corrosive settings. The 1/2"-20 UNF fine thread and Class 2A thread fit ensure tight, secure connections that withstand vibrations, making it ideal for partially threaded fastening in dynamic environments. By meeting ASME B18.2.1 and other standards, it delivers reliable performance, enhancing safety and longevity in industrial hex screw applications where failure is not an option.

Specification Summary & Compliance

This fastener adheres to precise dimensional tolerances, including a Class 2A thread fit for consistent engagement and UNF fine threading per industry standards. It complies with ASME B18.2.1 and SAE J429 specifications for quality assurance, and is verified as RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring environmental safety and regulatory adherence in global supply chains.