S-91268A129 1/4"-20 x 3 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 150,000 psi tensile strength for reliable performance in high-stress applications.
• Superior durability and wear resistance due to Rockwell C33 hardness, extending service life in demanding environments.
• Secure fastening with coarse UNC threading providing excellent grip and vibration resistance in various materials.
• Easy installation and removal with external hex drive design, compatible with standard tools for efficient maintenance.
• Precise thread fit (Class 2A) ensuring consistent engagement and reducing the risk of cross-threading or stripping.
• Partial threading design allows for controlled clamping force and optimal distribution along the shank.
• Compliance with industry standards including ASME B18.2.1 and SAE J429, guaranteeing interoperability and safety.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered from high-strength steel to address critical challenges in heavy machinery, construction, and automotive assemblies. The 1/4"-20 UNC coarse thread ensures rapid installation and robust holding power in coarse-grained materials, reducing assembly time while maintaining integrity under dynamic loads. With a minimum thread length of 3/4" and partial threading, it provides focused clamping force, minimizing stress concentration and preventing joint failure. The external hex drive facilitates high-torque application, making it ideal for environments where reliability and ease of service are paramount. These screws deliver consistent performance in applications requiring high tensile strength and resistance to shear forces, ensuring long-term operational safety.

Specification Summary & Compliance

This fastener adheres to Class 2A thread fit per UNC standards, ensuring dimensional accuracy and compatibility. It meets ASME B18.2.1 and SAE J429 Grade 8 specifications for mechanical properties and manufacturing consistency. The product is fully RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, confirming the absence of restricted hazardous substances and supporting environmental and safety regulations in industrial supply chains.