S-91257A558 1/4"-20 x 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 load-bearing capacity with 150,000 psi tensile strength for reliable performance in demanding applications
- Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh environments
- Optimized thread engagement with Class 2A thread fit ensuring smooth assembly and consistent clamping force
- Enhanced durability through Rockwell C33 hardness, maintaining structural integrity under heavy loads
- Secure installation enabled by external hex drive design for high torque application without stripping
- Versatile partial threading allowing for both secure fastening and adjustable positioning in assemblies
- Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for guaranteed interoperability
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers critical engineering solutions for industrial applications requiring high tensile strength and corrosion protection. The steel construction with zinc yellow-chromate plating provides superior resistance to environmental factors, while the 1/4"-20 UNC coarse thread ensures rapid assembly and reliable performance in vibration-prone environments. The partially threaded design with 3/4" minimum thread length offers optimal stress distribution, making it ideal for heavy machinery, structural steel connections, and equipment manufacturing where 150,000 psi tensile strength is essential for safety and longevity. The external hex drive facilitates high-torque installation in confined spaces, reducing assembly time while maintaining joint integrity.
Specification Summary & Compliance
Manufactured to precise Class 2A thread fit tolerances with 1/4"-20 UNC coarse threading in accordance with ASME B18.2.1 specifications. This fastener meets SAE J429 Grade 8 requirements for mechanical properties and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. The 4" length with partial threading provides consistent performance across industrial applications while maintaining dimensional accuracy per inch system standards.
