S-91257A568 1/4"-28 x 2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional strength for demanding applications with Grade 8 classification and 150,000 psi tensile strength, ensuring reliable performance under high stress.
• Superior corrosion resistance provided by the zinc yellow-chromate plating, extending the fastener's service life in harsh industrial environments.
• Precise and secure fastening with a UNF fine thread and Class 2A thread fit, offering excellent vibration resistance and reduced risk of loosening.
• Optimized for high-torque installation thanks to the external hex drive and hex head design, allowing for easy application with standard tools.
• Enhanced durability and wear resistance from the Rockwell C33 hardness, maintaining integrity through repeated use.
• Versatile partial threading on a 2" length, providing a non-threaded shank for precise clamping in a variety of assembly setups.
• Compliance with major industry standards including ASME B18.2.1 and SAE J429, ensuring consistent quality and interoperability.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy-duty industrial settings, where failure is not an option. Its high-strength steel construction and 150,000 psi tensile strength make it ideal for applications in machinery, automotive assemblies, and structural frameworks that endure significant dynamic loads and vibrations. The UNF fine thread and Class 2A thread fit ensure a tight, secure connection that minimizes the risk of loosening over time, a common pain point in high-vibration environments. Furthermore, the zinc yellow-chromate plating offers robust protection against corrosion, extending the lifespan of equipment exposed to moisture or chemicals. By incorporating this partially threaded screw with an external hex drive, engineers can achieve precise clamping force and easy installation, reducing assembly time and enhancing overall system reliability in demanding industrial applications.

Specification Summary & Compliance

This fastener adheres to precise dimensional standards with a Class 2A thread fit and UNF fine thread specification (1/4"-28), ensuring consistent performance and interchangeability. It is manufactured in compliance with ASME B18.2.1 and SAE J429 specifications, guaranteeing it meets rigorous engineering requirements. Additionally, the product is fully compliant with environmental regulations, including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), confirming it is free from hazardous substances and safe for use in various global markets.