S-91257A757 1/2"-20 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 load-bearing capacity with 150,000 psi tensile strength for reliable performance in high-stress applications
- Superior corrosion resistance through zinc yellow-chromate plating that protects against harsh industrial environments
- Precise torque transmission with external hex drive design ensuring secure installation and removal
- Optimized thread engagement through Class 2A thread fit and UNF fine threading for vibration resistance
- Reduced assembly weight with partial threading while maintaining 1 1/4" minimum thread length for sufficient grip
- Long-term reliability backed by Rockwell C33 hardness for sustained performance under repeated stress
- Regulatory compliance assurance meeting multiple industry standards for quality and environmental safety
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers critical engineering solutions for heavy machinery, structural assemblies, and industrial equipment where failure is not an option. The zinc yellow-chromate plated steel construction provides superior corrosion protection in demanding environments, while the 1/2"-20 UNF fine threading ensures secure fastening in vibration-prone applications. The partial threading design optimizes weight distribution without compromising the 1 1/4" minimum thread length required for proper joint integrity. Engineered to ASME B18.2.1 and SAE J429 specifications, this fastener solves common industrial challenges including material fatigue, environmental degradation, and precision fitting requirements in critical assembly operations.
Specification Summary & Compliance
Manufactured to precise Class 2A thread fit tolerances with UNF fine thread spacing (1/2"-20), this hex head screw maintains dimensional accuracy throughout its 3 3/4" length. Compliance with ASME B18.2.1 and SAE J429 standards ensures consistent quality and performance. The fastener meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, confirming its suitability for global industrial applications requiring strict chemical substance controls.
