S-91257A644 3/8"-16 x 5" 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 150,000 psi tensile strength, ideal for high-stress applications.
• Superior corrosion resistance from zinc yellow-chromate plating, extending service life in harsh environments.
• High hardness rating of Rockwell C33 ensures excellent wear resistance and durability.
• Reliable coarse UNC threading provides strong holding power and faster installation in various materials.
• Precise Class 2A thread fit guarantees consistent engagement and reduces the risk of cross-threading.
• Partially threaded design allows for secure clamping without unnecessary thread engagement.
• External hex drive enables easy installation and removal with standard tools.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered for demanding industrial settings where failure is not an option. The steel construction combined with zinc yellow-chromate plating provides robust protection against corrosion, making it suitable for outdoor machinery, construction equipment, and automotive assemblies. The 3/8"-16 UNC coarse thread ensures quick, secure fastening in metals and composites, while the partial threading concentrates clamping force precisely where needed. With its 150,000 psi tensile strength and Rockwell C33 hardness, it resists vibration loosening and mechanical stress, reducing maintenance needs and downtime in critical applications.

Specification Summary & Compliance

This fastener meets ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and performance. Threads are manufactured to Class 2A fit standards for consistent quality. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global markets.