S-91253A556 1/4"-20 x 2 1/2" ASTM F835 Alloy Steel Hex Drive Flat Head Screws
Alloy Steel Hex Drive Flat 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 Durability – Black-oxide alloy steel construction with Rockwell C39 hardness resists wear and corrosion in demanding environments.
- High Tensile Strength – 130,000 psi rating ensures reliable performance under heavy loads and vibration.
- Precise Thread Fit – Class 3A UNC coarse threads provide superior engagement and reduce cross-threading risks.
- Secure Hex Drive – 5/32" hex drive offers high torque application and prevents stripping during installation.
- Flush Mounting Design – Standard flat head with 82° countersink angle allows for smooth, unobtrusive surface finishing.
- Optimized Threading – Partially threaded design with 1" minimum thread length ensures strong grip where needed.
- Regulatory Compliance – Meets ASTM F835, RoHS 3, and REACH standards for safe, industry-approved use.
Professional Applications & Engineering Value
Engineered for industrial fastening where reliability is non-negotiable, these black-oxide alloy steel flat head screws address common challenges like material fatigue and loosening under stress. The UNC coarse thread and Class 3A fit enhance assembly speed and holding power in metals, plastics, and composite materials, while the hex drive ensures consistent torque transfer without cam-out. Ideal for machinery, automotive, and structural applications, the partially threaded shank and 82° countersink provide precise clamp load and flush seating, reducing the need for secondary finishing. The black-oxide finish adds a layer of corrosion resistance, extending service life in humid or abrasive conditions.
Specification Summary & Compliance
This screw adheres to inch system dimensions: 1/4"-20 UNC thread with Class 3A tolerance for tight fit, 2-1/2" length, and coarse thread spacing. Manufacturing follows ASTM F835 specifications, ensuring consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, confirming it is free of restricted substances for safe industrial use.
