S-91257A705 7/16"-20 x 3 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Strength & Durability: With a tensile strength of 150,000 PSI and Rockwell C33 hardness, this screw provides reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior Corrosion Resistance: The zinc yellow-chromate plating offers enhanced protection against rust and environmental degradation, extending the service life in harsh industrial conditions.
• Precise Thread Fit & Engagement: Class 2A thread fit ensures smooth assembly and secure fastening, minimizing cross-threading and improving installation efficiency.
• Optimized for Heavy-Duty Use: Grade 8 classification and UNF fine thread design deliver high clamping force and vibration resistance, ideal for machinery and structural assemblies.
• Compliant with Industry Standards: Meets ASME B18.2.1, SAE J429, RoHS 3, and REACH regulations, ensuring quality, safety, and environmental compliance for global supply chains.
• Versatile Partially Threaded Design: Allows for focused thread engagement on specific sections, providing flexibility in applications where unthreaded shank strength is critical.
• Easy Installation with External Hex Drive: The standard hex head enables quick tightening using common tools, reducing assembly time and labor costs.

Professional Applications & Engineering Value

This 7/16"-20 Grade 8 hex head screw is engineered to address critical challenges in industrial fastening, such as vibration loosening and corrosive wear. The UNF fine thread configuration enhances load distribution and resistance to dynamic stresses, making it suitable for heavy machinery, automotive systems, and construction equipment. Constructed from high-strength steel and finished with zinc yellow-chromate plating, it combats oxidation in humid or chemical-exposed environments, reducing maintenance downtime. The partially threaded shank provides added shear strength where full threading isn't required, offering engineers a reliable solution for bolting joints that demand both precision and endurance. Ideal for OEMs and MRO suppliers, this fastener ensures long-term reliability in industrial applications while adhering to stringent global standards.

Specification Summary & Compliance

This screw features a 7/16"-20 UNF fine thread with Class 2A thread fit for precise dimensional accuracy, and a 3 1/2" length with partial threading. It complies with ASME B18.2.1 and SAE J429 specifications, ensuring consistent manufacturing quality. Additionally, it is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting environmental and safety regulations for hazardous substance restrictions.