S-91257A856 3/4"-10 x 5 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 and Grade 8 classification, ideal for high-stress industrial applications.
- Enhanced corrosion resistance through zinc yellow-chromate plating, extending service life in harsh environments.
- Superior hardness and durability with Rockwell C33 rating, resisting wear and deformation under heavy use.
- Reliable coarse UNC threading (3/4"-10) for faster installation and reduced cross-threading risks in coarse materials.
- Secure external hex drive and 1 1/8" head width for easy, high-torque tightening with standard tools.
- Optimized partial threading (min 1 3/4") allowing unthreaded shank strength where needed, improving shear resistance.
- Precision manufacturing with Class 2A thread fit ensuring consistent engagement and vibration resistance.
Professional Applications & Engineering Value
Engineered for demanding industrial settings, this Grade 8 hex head screw combines high-strength steel and zinc yellow-chromate plating to address critical challenges like structural fatigue and environmental degradation. The 3/4"-10 UNC coarse thread facilitates quick assembly in heavy machinery, construction frameworks, and transportation equipment, while the external hex drive ensures reliable torque transmission. Its partially threaded design concentrates clamping force, minimizing loosening from vibrations—making it indispensable for bolted connections requiring sustained integrity under dynamic loads. Compliance with ASME B18.2.1 and SAE J429 standards guarantees interoperability and safety in OEM and MRO applications.
Specification Summary & Compliance
This fastener adheres to Class 2A thread fit tolerances for consistent assembly and meets ASME B18.2.1 and SAE J429 specifications. Dimensions include a 5 1/4" length, 1/2" head height, and 1 1/8" head width, with UNC coarse threading (3/4"-10) and right-hand direction. The zinc yellow-chromate finish provides RoHS and REACH compliance, enhancing environmental suitability without compromising the 150,000 psi tensile strength and Rockwell C33 hardness.
