S-91251A212 4-40 x 3" ASTM A574 Alloy Steel Socket Head Screws
Alloy Steel Socket 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 tensile strength of 170,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
- Superior corrosion resistance from the black-oxide finish on alloy steel, extending service life in harsh industrial environments.
- Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant assemblies, minimizing loosening over time.
- Fully threaded 3" length offers maximum grip and holding power across the entire fastener, ideal for thick materials or deep-set applications.
- High hardness (Rockwell C37) enhances wear resistance and durability, maintaining thread integrity through repeated use.
- Hex socket drive design allows for easy installation with standard tools, improving assembly efficiency and reducing stripping risks.
- Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency, environmental safety, and suitability for regulated industries.
Professional Applications & Engineering Value
Engineered for precision and reliability, this 4-40 UNC thread Socket Head Cap Screw addresses critical needs in industrial assembly where vibration resistance and high clamping force are paramount. The black-oxide alloy steel construction combats corrosion in humid or chemically exposed settings, while the coarse UNC thread and Class 3A fit deliver secure fastening in metals, plastics, and composites. Its fully threaded 3" length ensures uniform stress distribution, making it ideal for machinery, automotive components, and electronic enclosures requiring long-term stability. By integrating high tensile strength with a standardized hex drive, it streamlines maintenance and reduces downtime in production lines.
Specification Summary & Compliance
This screw adheres to UNC coarse thread standards with a Class 3A thread fit for precision alignment. Manufacturing follows ASTM A574 specifications, ensuring consistent material properties and performance. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of restricted hazardous substances for safe use in global markets.
