S-91251A211 4-40 x 2 1/4" 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 protects against rust and environmental degradation, extending service life in harsh industrial settings.
- Precise Class 3A thread fit guarantees tight tolerances and secure fastening, minimizing backlash and improving assembly accuracy.
- High hardness (Rockwell C37) provides excellent wear resistance, maintaining thread integrity and drive features through repeated use.
- Hex socket drive design allows for high torque application and easy installation in confined spaces, enhancing efficiency during assembly.
- Partially threaded shank offers optimal grip length control, preventing over-tightening and ensuring consistent clamping force.
- Compliance with ASTM A574, RoHS 3, and REACH ensures material quality and environmental safety, meeting rigorous industry and regulatory standards.
Professional Applications & Engineering Value
These 4-40 UNC thread socket head cap screws are engineered to address critical challenges in precision machinery, automotive, and aerospace assemblies. The black-oxide alloy steel construction combats corrosion while the coarse thread design facilitates quick installation and resists vibration loosening. With a Rockwell C37 hardness and 170,000 psi tensile strength, they withstand extreme mechanical loads and repetitive stress, making them ideal for high-stakes applications where fastener reliability is paramount. The hex drive and standard socket head profile enable secure tool engagement, reducing slip and damage during maintenance or disassembly.
Specification Summary & Compliance
This product features a 4-40 UNC coarse thread with Class 3A fit for precise dimensional accuracy, and a partially threaded rod with minimum thread length of 3/4". It conforms to ASTM A574 manufacturing specifications and is verified as RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring adherence to international quality and environmental regulations.
