S-91257A816 5/8"-11 x 5 1/2" 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
- Maximum load-bearing capability with 150,000 psi tensile strength for critical structural applications
- Superior corrosion protection through zinc yellow-chromate plating that withstands harsh industrial environments
- Enhanced durability with Rockwell C33 hardness that maintains integrity under repeated stress
- Reliable thread engagement with UNC coarse threads that resist vibration loosening
- Secure installation using standard external hex drive for high-torque applications
- Precision manufacturing with Class 2A thread fit ensuring consistent performance
- Partial threading design providing optimal grip strength where full thread engagement isn't required
Professional Applications & Engineering Value
These Grade 8 hex head screws deliver exceptional engineering value in demanding industrial settings where failure is not an option. The 5/8"-11 UNC coarse thread configuration provides superior resistance to vibration-induced loosening in heavy machinery, construction equipment, and structural steel applications. The zinc yellow-chromate plating creates a robust barrier against corrosion in outdoor or chemically aggressive environments, significantly extending service life. With partial threading and precise Class 2A thread fit, these fasteners offer optimal clamping force distribution while preventing thread damage during installation. The combination of 150,000 psi tensile strength and Rockwell C33 hardness ensures these screws maintain integrity under extreme mechanical stress, making them ideal for critical connections in manufacturing, infrastructure, and heavy equipment assembly.
Specification Summary & Compliance
Manufactured to exacting standards with Class 2A thread fit and UNC coarse thread specifications ensuring dimensional accuracy and reliable performance. These hex head screws comply with ASME B18.2.1 and SAE J429 Grade 8 specifications for mechanical properties and dimensional requirements. The product meets RoHS 3 (2015/863/EU) compliance for restricted substances and REACH (EC 1907/2006) regulations for chemical safety, ensuring environmental responsibility and workplace safety standards.
