S-91257A615 5/16"-24 x 2 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength – With a 150,000 psi rating, 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 service life in harsh conditions.
• High Hardness for Durability – Rockwell C33 hardness ensures the screw maintains its integrity under heavy loads and repeated use, minimizing wear and deformation.
• Precise Thread Fit – Class 2A thread fit allows for smooth assembly and secure fastening, reducing installation time and improving joint reliability.
• Optimized for Heavy-Duty Use – Partially threaded design with fine UNF threads provides strong grip and vibration resistance, ideal for machinery and structural applications.
• Compliance with Industry Standards – Meets ASME B18.2.1 specifications, ensuring consistent quality and interchangeability in professional settings.
• Environmental and Safety Compliance – RoHS 3 and REACH compliant, making it suitable for regulated industries without harmful substances.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address common industrial challenges, such as vibration loosening and corrosion in demanding environments. The steel material combined with zinc yellow-chromate plating provides a robust barrier against moisture and chemicals, reducing maintenance needs in applications like heavy machinery, automotive assemblies, and construction frameworks. Its partially threaded design with 5/16"-24 UNF fine threads ensures precise engagement and high clamp force, preventing joint failure under dynamic loads. By adhering to ASME B18.2.1 standards, it guarantees reliability in critical systems, making it a top choice for engineers seeking durable, high-performance fasteners that meet stringent industry and environmental regulations.

Specification Summary & Compliance

This screw features a Class 2A thread fit for precise tolerances, with UNF fine threads (5/16"-24) and a minimum thread length of 7/8". It complies with ASME B18.2.1 manufacturing specifications and is certified RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, ensuring it meets environmental and safety standards for industrial use.