S-91257A642 3/8"-16 x 4 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws
High-Strength Grade 8 Steel Hex Head Screws
Image may differ from product. See technical specification for details.
Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
- Fast delivery
- Enjoy discounts on bulk purchases
- Secure Payment
- Fast Global Shipping
Key Features & Benefits at a Glance
- Exceptional tensile strength of 150,000 PSI ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
- Superior corrosion resistance from zinc yellow-chromate plating extends service life in harsh industrial or outdoor environments.
- High hardness rating (Rockwell C33) provides excellent wear resistance and durability under repeated loads.
- Coarse UNC threads with Class 2A fit allow for quick assembly and secure fastening, minimizing cross-threading risks.
- Partially threaded design offers optimal clamping force distribution, ideal for materials requiring precise joint integrity.
- External hex drive and hex head enable easy installation with standard tools, improving workflow efficiency.
- Compliance with ASME B18.2.1 and RoHS/REACH guarantees consistent quality and environmental safety for global projects.
Professional Applications & Engineering Value
This Grade 8 hex head screw is engineered to address critical challenges in heavy machinery, construction, and structural assemblies where vibration, high loads, and environmental exposure are common. The steel material combined with zinc yellow-chromate plating provides a robust barrier against rust and chemical degradation, ensuring long-term reliability. The coarse UNC thread and Class 2A thread fit facilitate rapid installation while maintaining tight tolerances, reducing assembly time and labor costs. With a partial threading design, it delivers superior clamping force without compromising shear strength, making it ideal for bolting applications in automotive frames, industrial equipment, and infrastructure projects that demand high tensile strength and durability under dynamic conditions.
Specification Summary & Compliance
This fastener adheres to ASME B18.2.1 specifications and features a 3/8"-16 UNC coarse thread with Class 2A thread fit for precise dimensional accuracy. It meets Grade 8 strength requirements, including a tensile strength of 150,000 PSI and Rockwell C33 hardness. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free from hazardous substances and suitable for use in regulated industries.
