S-91257A565 1/4"-28 x 1 1/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional strength for heavy-duty applications with Grade 8 classification and 150,000 psi tensile strength, ensuring reliable performance under high stress.
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh industrial environments.
• Precise and secure fastening with UNF fine threads and Class 2A thread fit, minimizing the risk of loosening in critical assemblies.
• High durability and wear resistance due to Rockwell C33 hardness, maintaining integrity through repeated use and vibration.
• Easy installation and removal with an external hex drive and standard hex head design, compatible with common tools for efficient maintenance.
• Versatile partial threading allowing for controlled clamping force and reduced thread damage in adjustable connections.
• Compliance with industry standards including ASME B18.2.1, ensuring consistent quality and interchangeability in professional settings.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address common challenges in demanding industrial applications, such as machinery assembly, automotive systems, and structural frameworks. The steel material combined with a zinc yellow-chromate finish offers robust protection against corrosion and oxidation, which is critical in environments exposed to moisture or chemicals. Featuring a 1/4"-28 UNF fine thread and Class 2A thread fit, it ensures tight, vibration-resistant connections that prevent failures in high-load scenarios. The partial threading design allows for precise adjustment and reduces stress concentration, making it ideal for applications requiring reliable, long-term fastening without frequent maintenance. By integrating these elements, this fastener enhances operational safety and reduces downtime in heavy-duty industrial and engineering projects.

Specification Summary & Compliance

This product adheres to precise dimensional standards with a Class 2A thread fit and UNF fine thread specifications, ensuring accurate and consistent performance. It meets ASME B18.2.1 manufacturing guidelines for hex head screws and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its safety and environmental responsibility for global industrial use.