S-91257A576 1/4"-28 x 3 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws
High-Strength Grade 8 Steel Hex Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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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 environments.
- High hardness rating (Rockwell C33) provides excellent wear resistance and durability under repetitive loads.
- Precise Class 2A thread fit allows for smooth assembly and secure fastening with reduced cross-threading risks.
- Partially threaded design offers optimal clamping force distribution, ideal for applications requiring vibration resistance.
- External hex drive enables easy installation and removal with standard tools, improving maintenance efficiency.
- Compliance with ASME B18.2.1/SAE J429 standards guarantees consistent quality and interchangeability in industrial assemblies.
Professional Applications & Engineering Value
This Grade 8 hex head screw is engineered to address critical challenges in heavy machinery, automotive, and construction sectors where high tensile strength and corrosion resistance are paramount. The 1/4"-28 UNF fine thread provides superior holding power in materials prone to stress cracking, while the zinc yellow-chromate plating effectively combats oxidation in humid or chemical-exposed environments. Its partially threaded shank concentrates clamping force precisely, preventing joint loosening under dynamic loads. By meeting ASME B18.2.1 specifications, this fastener ensures reliable performance in structural assemblies, engine components, and industrial equipment requiring 150,000 psi tensile strength and consistent thread engagement.
Specification Summary & Compliance
This hex head screw features a 1/4"-28 UNF fine thread with Class 2A thread fit for precise tolerance, a 3 3/4" length with 3/4" minimum thread length, and external hex drive for standard tool compatibility. Manufactured from steel with zinc yellow-chromate plating, it complies with ASME B18.2.1 and SAE J429 standards for dimensional accuracy and mechanical properties, ensuring reliability in regulated industrial applications.
