S-91257A497 1/2"-20 x 9" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength – With 150,000 psi tensile strength, 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 & Durability – Rockwell C33 hardness ensures the screw maintains its structural integrity under heavy loads and repeated use.
• Precision Thread Fit – Class 2A thread fit with 1/2"-20 UNF fine threading ensures secure, vibration-resistant connections in critical assemblies.
• Optimized for Heavy-Duty Use – Partially threaded design and Grade 8 strength make it ideal for applications requiring robust, dependable fastening without full-length threading.
• Wide Industrial Compliance – Meets ASME B18.2.1 and SAE J429 standards, ensuring consistency and reliability in engineering and manufacturing processes.
• Environmental & Safety Compliance – RoHS 3 and REACH compliant, supporting sustainable and safe usage in regulated industries.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address demanding industrial challenges, such as vibration loosening and corrosion in heavy machinery, construction, and automotive assemblies. The 1/2"-20 UNF fine threading and Class 2A thread fit provide precise engagement, minimizing play and enhancing joint integrity under dynamic loads. The zinc yellow-chromate plating adds a critical layer of corrosion resistance, making it suitable for outdoor or humid environments. With partial threading, it concentrates strength where needed, reducing weight and cost without compromising on the 150,000 psi tensile strength required for structural and high-torque applications. Its compliance with ASME B18.2.1 ensures it meets rigorous industry specifications for reliability and safety.

Specification Summary & Compliance

This screw features a 1/2"-20 UNF fine thread with Class 2A tolerance for precise fit, a 9" length, and partial threading starting from a minimum thread length of 1 1/2". It conforms to ASME B18.2.1 and SAE J429 Grade 8 standards, ensuring high-quality manufacturing. Additionally, it is RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, meeting environmental and safety regulations for industrial use.