S-91257A455 5/16"-24 x 8" 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 or outdoor industrial environments.
- High hardness rating (Rockwell C33) provides excellent wear resistance and durability under repetitive loads.
- Fine UNF threading offers improved vibration resistance and more precise tension control compared to coarse threads.
- Class 2A thread fit ensures consistent, easy assembly while maintaining secure fastening without cross-threading issues.
- Partial threading design allows for concentrated clamping force where needed most, optimizing joint integrity.
- External hex drive enables high-torque installation with standard tools, speeding up assembly processes.
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers critical performance where structural integrity is non-negotiable. The 150,000 PSI tensile strength and Rockwell C33 hardness directly address common failure points in heavy machinery, construction equipment, and automotive assemblies subjected to dynamic loads. The zinc yellow-chromate plating provides a robust barrier against corrosion-induced weakening, particularly valuable in manufacturing facilities with chemical exposure or outdoor installations. With its 5/16"-24 UNF fine thread and partial threading, engineers achieve superior vibration resistance in powertrain components, industrial frames, and hydraulic systems where loosening could cause catastrophic downtime. The 8" length accommodates thick material stacks common in structural steel connections and equipment mounting.
Specification Summary & Compliance
Manufactured to ASME B18.2.1 and SAE J429 specifications, this fastener maintains precise Class 2A thread fit tolerances for consistent engagement. The inch system measurements ensure compatibility with North American industrial standards. The zinc yellow-chromate finish meets typical industrial corrosion protection requirements while the Grade 8 classification guarantees mechanical properties through rigorous material testing and manufacturing controls.
