S-91257A211 3/4"-16 x 4 1/4" 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
- Maximum load-bearing capacity with 150,000 psi tensile strength for critical heavy-duty applications
- Superior corrosion protection through zinc yellow-chromate plating that withstands harsh industrial environments
- Enhanced installation efficiency with external hex drive design providing secure tool engagement and torque transmission
- Precise thread engagement with Class 2A thread fit ensuring reliable fastening in UNF fine-thread applications
- Optimized strength-to-weight ratio through Grade 8 steel construction with Rockwell C33 hardness
- Reduced material stress concentration with partial threading design that maintains shank strength
- Industry-standard compatibility meeting ASME B18.2.1 and SAE J429 specifications for quality assurance
Professional Applications & Engineering Value
These Grade 8 hex head screws deliver exceptional performance in demanding industrial settings where failure is not an option. The 3/4"-16 UNF fine threading provides superior vibration resistance compared to coarse threads, making them ideal for machinery, heavy equipment, and structural applications subject to dynamic loads. The zinc yellow-chromate plating creates a protective barrier against corrosion while maintaining electrical conductivity for grounding applications. With partial threading and substantial 1 3/4" minimum thread length, these fasteners distribute shear forces efficiently while the 1 1/8" hex head accommodates standard industrial tools for rapid assembly. Engineered for heavy-duty fastening requirements, they solve critical challenges in construction, manufacturing, and equipment maintenance where high clamp load and reliability are paramount.
Specification Summary & Compliance
This 3/4"-16 UNF hex head screw features precise Class 2A thread fit tolerances and 4 1/4" overall length with partial threading. Manufactured from high-strength Grade 8 steel meeting SAE J429 standards and compliant with ASME B18.2.1 dimensional specifications. The zinc yellow-chromate plating provides corrosion resistance while maintaining compliance with industrial fastener requirements for heavy machinery and structural applications.
