S-91247A446 5/8"-18 x 4 1/2" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Superior tensile strength of 120,000 psi ensures reliable performance in high-stress industrial applications, reducing the risk of fastener failure.
• Zinc plating finish provides excellent corrosion resistance, extending the screw's service life in harsh or outdoor environments.
• Grade 5 steel construction with Rockwell C25 hardness offers a robust balance of strength and durability for demanding mechanical assemblies.
• Fine UNF threading (5/8"-18) with Class 2A fit delivers precise, vibration-resistant connections, minimizing loosening in dynamic loads.
• External hex drive and hex head design allows for easy installation and high torque application with standard tools, improving assembly efficiency.
• Partially threaded shank provides unthreaded grip length for better clamping force distribution in structured joints.
• Compliance with ASME B18.2.1 and SAE J429 standards guarantees consistent quality and interchangeability in OEM and MRO applications.

Professional Applications & Engineering Value

This 5/8"-18 UNF Grade 5 steel hex head screw is engineered to address critical challenges in heavy-duty industrial settings, such as machinery assembly, construction equipment, and automotive frameworks. The fine thread configuration enhances grip in materials prone to vibration, while the zinc plated surface resists oxidation, reducing maintenance needs. With a high tensile strength of 120,000 psi and Rockwell C25 hardness, it withstands extreme loads without deformation. The partially threaded design ensures optimal stress distribution, making it ideal for bolted connections requiring precise clamp load. By meeting ASME B18.2.1 specifications, it delivers reliable performance in applications demanding strict adherence to engineering standards, from manufacturing plants to infrastructure projects.

Specification Summary & Compliance

This screw features a Class 2A thread fit for consistent assembly tolerance, manufactured in accordance with ASME B18.2.1 and SAE J429 standards. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material restrictions are met. Dimensions include a 4 1/2" length with 5/8"-18 UNF fine threads and a minimum thread length of 1 1/2", providing precise engineering compatibility for industrial fastening systems.