S-91257A609 5/16"-24 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 Load-Bearing Capacity – With a tensile strength of 150,000 PSI and Rockwell C33 hardness, this screw reliably handles high-stress applications without failure.
• Superior Corrosion Resistance – Zinc yellow-chromate plating provides a durable barrier against rust and environmental degradation, extending service life in harsh conditions.
• Precise Fastening & Vibration Resistance – UNF fine thread with Class 2A fit ensures tight, accurate engagement, reducing the risk of loosening under dynamic loads.
• High-Strength Material Construction – Made from Grade 8 steel, this fastener meets rigorous industrial demands for durability and mechanical performance.
• Easy Installation & Removal – External hex drive and standard hex head design allow for straightforward torque application using common tools.
• Optimized Thread Design – Partially threaded shank provides unthreaded grip length for improved clamping force in assembled components.
• Regulatory Compliance & Reliability – Conforms to ASME B18.2.1 and SAE J429 standards, ensuring consistent quality and interchangeability.

Professional Applications & Engineering Value

This Grade 8 steel hex head screw is engineered to address critical fastening challenges in heavy machinery, automotive assemblies, and structural frameworks. The zinc yellow-chromate plating offers robust protection against corrosion, making it suitable for outdoor or high-moisture environments. Its UNF fine thread and Class 2A thread fit deliver precise alignment and secure holding power, minimizing the risk of strip-out or vibration-induced failure. The partially threaded design concentrates stress away from the thread roots, enhancing fatigue resistance in dynamic applications. Ideal for use in engine components, construction equipment, and industrial fixtures, this screw combines high tensile strength with reliable performance under continuous load.

Specification Summary & Compliance

This fastener features a 5/16"-24 UNF fine thread with Class 2A fit for consistent dimensional accuracy. It meets ASME B18.2.1 and SAE J429 specifications, ensuring adherence to recognized engineering standards. The screw is also compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its suitability for use in regulated markets without hazardous substances.